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<p>Architecture in a Climate of Change</p><p>AIAC-FM 03/29/2005 17:25 Page i</p><p>AIAC-FM 03/29/2005 17:25 Page ii</p><p>Architecture in a Climate</p><p>of Change</p><p>A guide to sustainable design</p><p>Peter F. Smith</p><p>AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD</p><p>PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO</p><p>Architectural Press is an imprint of Elsevier</p><p>AIAC-FM 03/29/2005 17:25 Page iii</p><p>Architectural Press</p><p>An imprint of Elsevier</p><p>Linacre House, Jordan Hill, Oxford OX2 8DP</p><p>30 Corporate Drive, Burlington, MA 01803</p><p>First published 2001</p><p>Second edition 2005</p><p>Copyright © 2001, 2005, Peter F. Smith. All rights reserved</p><p>The right of Peter F. Smith to be identified as the author of this work have been asserted in accordance with the</p><p>Copyright, Designs, and Patents Act 1988</p><p>No part of this publication may be reproduced in any material form (including photocopying or storing in any</p><p>medium by electronic means and whether or not transiently or incidentally to some other use of this publication)</p><p>without the written permission of the copyright holder except in accordance with the provision of the Copyright,</p><p>Designs, and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90</p><p>Tottenham Court Road, London, England W1T 4LP. Applications for the copyright holder’s written permission to</p><p>reproduce any part of this publication should be addressed to the publisher.</p><p>Permissions may be sought directly from Elsevier’ Science and Technology Rights Department in Oxford, UK:</p><p>phone: (�44) (0) 1865 843830; fax: (�44) (0) 1865 853333; e-mail: permission@elsevier.co.uk. You may also</p><p>complete your request on-line via the Elsevier homepage (http://www.elsevier.com), by selecting “Customer</p><p>Support” and then “Obtaining Permissions”.</p><p>British Library Cataloguing in Publication Data</p><p>A catalogue record for this book is available from the British Library</p><p>ISBN 0 7506 65440</p><p>Typeset by Newgen Imaging Systems Pvt Ltd, Chennai, India</p><p>Printed and bound in Great Britain</p><p>For information on all Architectural Press publication</p><p>visit our web site at http://books.elsevier.com</p><p>AIAC-FM 03/29/2005 17:25 Page iv</p><p>Contents</p><p>v</p><p>Foreword xi</p><p>Acknowledgements xii</p><p>Introduction xiii</p><p>1 Climate change – nature or human nature? 1</p><p>The carbon cycle 1</p><p>The greenhouse effect 2</p><p>Climate change – the paleoclimate record 3</p><p>Causes of climate fluctuation 4</p><p>The evidence 7</p><p>2 Predictions 12</p><p>Recent uncertainties 17</p><p>What is being done? 19</p><p>The outlook for energy 20</p><p>The nuclear option 23</p><p>3 Renewable technologies – the marine environment 26</p><p>The UK energy picture 26</p><p>Energy from rivers and seas 28</p><p>Hydroelectric generation 28</p><p>Small-scale hydro 29</p><p>‘Run of river’ systems 29</p><p>Tidal energy 30</p><p>4 Renewable technologies – the wider spectrum 42</p><p>Passive solar energy 42</p><p>Active solar 42</p><p>Solar thermal electricity 43</p><p>The parabolic solar thermal concentrator 44</p><p>Photovoltaics 45</p><p>Wind power 45</p><p>Biomass and waste utilisation 47</p><p>AIAC-FM 03/29/2005 17:25 Page v</p><p>Hydrogen 50</p><p>Nuclear power 50</p><p>5 Low energy techniques for housing 52</p><p>Construction systems 52</p><p>Solar design 54</p><p>Types of solar thermal collector 62</p><p>Windows and glazing 64</p><p>6 Insulation 68</p><p>The range of insulation options 69</p><p>High and superinsulation 72</p><p>Transparent insulation materials 77</p><p>Insulation – the technical risks 77</p><p>7 Domestic energy 80</p><p>Photovoltaic systems 80</p><p>Micro-combined heat and power (CHP) 87</p><p>Fuel cells 90</p><p>Embodied energy and materials 91</p><p>8 Advanced and ultra-low energy houses 93</p><p>The Beddington Zero Energy Development – BedZED 94</p><p>The David Wilson Millennium Eco-House 94</p><p>Demonstration House for the Future, South Wales 95</p><p>The prospects for wood 98</p><p>The external environment 103</p><p>Summary checklist for the energy efficient</p><p>design of dwellings 104</p><p>Report by Arup Research and Development for the</p><p>DTI’s Partners in Innovation Programme 2004 107</p><p>9 Harvesting wind and water 108</p><p>Small wind turbines 108</p><p>Types of small-scale wind turbine 110</p><p>Building integrated systems 114</p><p>Conservation of water in housing 115</p><p>Domestic appliances 117</p><p>10 Existing housing: a challenge and opportunity 118</p><p>The remedy 121</p><p>Case study 122</p><p>11 Low energy techniques for non-domestic buildings 127</p><p>Design principles 127</p><p>Environmental considerations in the design of offices 128</p><p>Passive solar design 129</p><p>CONTENTS</p><p>vi</p><p>AIAC-FM 03/29/2005 17:25 Page vi</p><p>12 Ventilation 138</p><p>Natural ventilation 138</p><p>Internal air flow and ventilation 138</p><p>Unassisted natural ventilation 140</p><p>Mechanically assisted ventilation 145</p><p>Cooling strategies 151</p><p>Evaporative cooling 152</p><p>Additional cooling strategies 154</p><p>The ecological tower 154</p><p>Summary 160</p><p>Air conditioning 161</p><p>13 Energy options 162</p><p>The fuel cell 163</p><p>Proton exchange membrane fuel cell 164</p><p>Phosphoric acid fuel cell (PAFC) 165</p><p>Solid oxide fuel cell (SOFC) 165</p><p>Alkaline fuel cell (AFC) 166</p><p>Moltel carbonate fuel cell (MCFC) 166</p><p>Storage techniques – electricity 169</p><p>Photovoltaic applications 170</p><p>Heat pumps 171</p><p>Energy storage – heating and cooling 174</p><p>Seasonal energy storage 176</p><p>Electricity storage 177</p><p>Building management systems 178</p><p>Tools for environmental design 179</p><p>Report by Arup Research and Development</p><p>for the DTI’s Partners in Innovation</p><p>Programme 2004 180</p><p>14 Lighting – designing for daylight 181</p><p>Design considerations 182</p><p>The atrium 184</p><p>Light shelves 185</p><p>Prismatic glazing 185</p><p>Light pipes 185</p><p>Holographic glazing 187</p><p>Solar shading 187</p><p>15 Lighting – and human failings 188</p><p>Photoelectric control 189</p><p>Glare 190</p><p>Dimming control and occupancy sensing 190</p><p>Switches 191</p><p>System management 191</p><p>CONTENTS</p><p>vii</p><p>AIAC-FM 03/29/2005 17:25 Page vii</p><p>Air conditioned offices 192</p><p>Lighting – conditions for success 192</p><p>Summary of design considerations 193</p><p>16 Cautionary notes 195</p><p>Why do things go wrong? 195</p><p>High profile/low profile 196</p><p>The ‘high-tech demand’ 196</p><p>Operational difficulties 197</p><p>Building related illness 197</p><p>Inherent inefficiencies 197</p><p>Common architectural problems 198</p><p>Common engineering problems 198</p><p>Avoiding air conditioning – the issues 198</p><p>Common failures leading to energy waste 199</p><p>The human factor 199</p><p>Summary of recommendations 200</p><p>Conclusions 200</p><p>17 Life-cycle assessment and recycling 202</p><p>Waste disposal 202</p><p>Recycling 203</p><p>Life-cycle assessment 205</p><p>Whole life costing 205</p><p>Eco-materials 206</p><p>External finishes 207</p><p>Paints 207</p><p>Materials and embodied energy 208</p><p>Low energy Conference Centre, Earth Centre,</p><p>Doncaster 209</p><p>Recycling strategy checklist 211</p><p>18 State of the art case studies 212</p><p>The National Assembly for Wales 212</p><p>Zuckermann Institute for Connective Environmental</p><p>Research (ZICER) 214</p><p>Social housing 217</p><p>Beaufort Court, Lillie Road, Fulham, London, 2003 217</p><p>Beddington Zero Energy Development (BedZED) 218</p><p>Beaufort court renewable energy centre zero</p><p>emissions building 225</p><p>19 Integrated district environmental design 235</p><p>Ecological City of Tomorrow, Malmo, Sweden 236</p><p>Towards the less unsustainable city 238</p><p>CONTENTS</p><p>viii</p><p>AIAC-FM 03/29/2005 17:25 Page viii</p><p>20 An American perspective 245</p><p>Glenwood Park, Atlanta, Georgia 248</p><p>21 Emergent technologies and future prospects 250</p><p>Energy for the future 251</p><p>Next generation solar cells 254</p><p>Artificial photosynthesis 256</p><p>Energy storage 256</p><p>Hydrogen storage 257</p><p>Flywheel technology 257</p><p>Advances in lighting 258</p><p>The photonic revolution 259</p><p>Smart materials 260</p><p>Smart fluids 261</p><p>Socio-economic factors 262</p><p>Appendix 1 Key indicators for sustainable design 265</p><p>Appendix 2 An outline sustainability syllabus for designers 267</p><p>Index 275</p><p>CONTENTS</p><p>ix</p><p>AIAC-FM 03/29/2005 17:25 Page ix</p><p>AIAC-FM 03/29/2005 17:25 Page x</p><p>Foreword</p><p>This updated book is essential reading especially as it considers the</p><p>‘why’ as well as the ‘what’ of sustainable architecture. There is now wide</p><p>agreement that halting global warming and its climatic consequences</p><p>is likely to be the greatest challenge that we shall face in this century. As</p><p>populations increase and, at the same time, gravitate to cities, build-</p><p>ings old and new should be a prime target in the battle to reverse the</p><p>demand for fossil-based energy.</p><p>Students and practitioners</p><p>have described them as ‘heroically optimistic’, a verdict which therefore</p><p>also applies to the government’s target of 20 per cent reduction in CO2</p><p>emissions by 2010 since that target assumes full bore production by its</p><p>ageing reactors. In fact nuclear output dropped 4 per cent in 1999 and</p><p>10 per cent in 2000 and in the latter year coal fired generation was up</p><p>13 per cent. All but two of the Magnox stations have closure dates</p><p>before 2008. The pressurised water and gas cooled reactors have been</p><p>beset with problems. By 2014 75 per cent of nuclear will have been</p><p>decommissioned. The DTI’s energy predictions assume that, for the</p><p>next decade, the creaking nuclear industry will operate at full capacity</p><p>with an unprecedented rate of efficiency. After that, renewables, gas</p><p>generation and possibly a new batch of nuclear generators will fill the</p><p>vacuum. As we have noted gas has its uncertainties. The projected fuel</p><p>mix for the UK in 2010 is:</p><p>● Coal 16 per cent</p><p>● Nuclear 16 per cent</p><p>● Renewables 10 per cent</p><p>● Gas 57 per cent.</p><p>However, in 2008 the EU will enforce desulphurisation regulations on</p><p>coal fired plants making them uneconomic. Their only option will be to</p><p>switch to biofuels such as rapid rotation crops which is already being</p><p>pioneered at the massive Drax power station in Yorkshire. The use</p><p>of biofuels may offer a future for coal fired power stations. A plant</p><p>Figure 2.6</p><p>World oil and gas production to 2050</p><p>1930 1940 1950 1980 1970 1980 1990 2000 2010 2020 2030 2040 2050</p><p>0</p><p>5</p><p>10</p><p>15</p><p>20</p><p>25</p><p>30</p><p>35</p><p>B</p><p>ill</p><p>io</p><p>n</p><p>ba</p><p>rr</p><p>el</p><p>s</p><p>a</p><p>ye</p><p>ar</p><p>(</p><p>G</p><p>b/</p><p>a)</p><p>Russia</p><p>US-48 Europe Russia Other M.East Heavy etc. Deepwater Polar NGL</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 23</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>24</p><p>operated by Biojoule in East Anglia is already producing 15 000 tonnes</p><p>a year of specially processed wood for partial fuel replacement in coal</p><p>fired power plants.</p><p>The obvious conclusion to draw from all this is that buildings being</p><p>designed now will, in most cases, still be functioning when the screws</p><p>on fossil fuels are really tightening. For buildings wholly reliant on</p><p>fossil-based energy, it will be impossible to make accurate predictions</p><p>as to running costs in, say, ten years’ time. What is certain is that energy</p><p>prices will rise steeply since there is still only patchy evidence of the will</p><p>to stave off this crisis by the deployment of renewable energy tech-</p><p>nologies. The pressure to incorporate the external costs like damage to</p><p>health, buildings and above all the biosphere into the price of fossil will</p><p>intensify as the effects of global warming become increasingly threat-</p><p>ening. The government undertaking is to meet 10 per cent of electric-</p><p>ity demand by 2010 from renewable sources. What tends to be</p><p>overlooked is that, by then, demand will probably have increased by</p><p>more than this percentage and, at the same time, many of the nuclear</p><p>power plants are likely to have been decommissioned. By 2015 the UK</p><p>could be facing an energy vacuum which emphasises the need to take</p><p>the plunge into renewable technologies as a matter of urgency, which</p><p>makes the latest offering from the European Environment Agency (EEA)</p><p>report of 2004 all the more remarkable and disturbing. It states that</p><p>within the European Union the share of renewable electricity rose from</p><p>12 per cent in 1990 to 14 per cent in 2001. The EU target is 21 per cent</p><p>Figure 2.7</p><p>Comparison of electricity derived from</p><p>renewables in 25 EU states</p><p>(source: European Environment Agency</p><p>2004)</p><p>Indicative targets</p><p>All other renewables</p><p>Industrial and municipal waste</p><p>Large hydropower</p><p>80</p><p>70</p><p>60</p><p>50</p><p>40</p><p>30</p><p>20</p><p>10</p><p>0</p><p>R</p><p>en</p><p>ew</p><p>ab</p><p>le</p><p>s</p><p>as</p><p>s</p><p>ha</p><p>re</p><p>o</p><p>f</p><p>el</p><p>ec</p><p>tr</p><p>ic</p><p>ity</p><p>c</p><p>on</p><p>su</p><p>m</p><p>pt</p><p>io</p><p>n</p><p>(%</p><p>)</p><p>Aus</p><p>tri</p><p>a</p><p>Swed</p><p>en</p><p>La</p><p>tvi</p><p>a</p><p>Por</p><p>tu</p><p>ga</p><p>l</p><p>Slov</p><p>en</p><p>ia</p><p>Finl</p><p>an</p><p>d</p><p>Spa</p><p>in</p><p>Slov</p><p>ak</p><p>R</p><p>ep</p><p>ub</p><p>lic</p><p>Den</p><p>m</p><p>ar</p><p>k</p><p>Ita</p><p>ly</p><p>Fr</p><p>an</p><p>ce</p><p>EU-2</p><p>5</p><p>Ger</p><p>m</p><p>an</p><p>y</p><p>Gre</p><p>ec</p><p>e</p><p>Ire</p><p>lan</p><p>d</p><p>Net</p><p>he</p><p>rla</p><p>nd</p><p>s</p><p>Cze</p><p>ch</p><p>R</p><p>ep</p><p>ub</p><p>lic</p><p>Lu</p><p>xu</p><p>em</p><p>bo</p><p>ur</p><p>g</p><p>Lit</p><p>hu</p><p>an</p><p>ia</p><p>Unit</p><p>ed</p><p>K</p><p>ing</p><p>do</p><p>m</p><p>Pola</p><p>nd</p><p>Belg</p><p>ium</p><p>Hun</p><p>ga</p><p>ry</p><p>Esto</p><p>nia</p><p>Cyp</p><p>ru</p><p>s</p><p>M</p><p>alt</p><p>a</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 24</p><p>by 2010, suggesting that much more needs to be done. The EEA has</p><p>produced a histogram which shows the relative performance of mem-</p><p>ber states. The UK is fourth from bottom of the table of all countries</p><p>which have a contribution from renewables. (Figure 2.7) (EEA 2004;</p><p>Signals 2004, a European Environment Agency Update on selected</p><p>issues, Copenhagen, May 2004).</p><p>PREDICTIONS</p><p>25</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 25</p><p>26</p><p>Chapter</p><p>Three</p><p>Renewable</p><p>technologies – the</p><p>marine environment</p><p>Two quotes set the scene for this chapter:</p><p>A sustainable energy system is probably the single most</p><p>important milestone in our efforts to create a sustainable</p><p>future . . . Decarbonisation of the energy system is task</p><p>number one.</p><p>Oystein Dahle, Chairman.</p><p>Worldwatch Institute</p><p>and</p><p>Global civilisation can only escape the life-threatening</p><p>fossil-fuel resource trap if every effort is made to bring about</p><p>an immediate transition to renewable and environmentally</p><p>sustainable resources and thereby end the dependence on</p><p>fossil fuels.</p><p>Hermann Scheer, The Solar Economy,</p><p>Earthscan 2002, p. 7</p><p>The UK energy picture</p><p>In 2002 total inland energy consumption in the UK was 229.6 million</p><p>tonnes of oil equivalent (mtoe). Nuclear contributed 21.3 mtoe to the</p><p>total. Renewables and energy from waste accounted for a mere 2.7</p><p>mtoe (UK Energy in Brief, DTI, July 2003). Is it fantasy to support that</p><p>renewable energy sources could equal, even exceed, this capacity</p><p>without help from nuclear? This is a key question since the Energy</p><p>White Paper of February 2002 put nuclear on hold pending a demon-</p><p>stration that renewables could fill the void left by the decommissioning</p><p>of the present cluster of nuclear facilities.</p><p>The government has declared a target of 10.4 per cent for renew-</p><p>ables by 2010 and an aspiration to achieve 20 per cent by 2020. The 20 per</p><p>cent figure is significant since it represents the limit at which the present</p><p>structure of the grid can accommodate small-scale and intermittent</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 26</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>27</p><p>suppliers. Beyond this percentage the grid would have to be reconfigured</p><p>to encompass extensive distributed generation, as recommended by the</p><p>Royal Commission on Environmental Pollution (ibid., p. xi).</p><p>As far as the major power distributors are concerned, the 20 per cent</p><p>threshold may well be regarded as the ‘red line’ beyond which they will be</p><p>forced to run on less than full capacity, at the same time compensating for</p><p>fluctuations in the supply from renewables. According to Hermann Scheer</p><p>this would threaten the long-term ambitions of the power industry which</p><p>sees the prospect of ultimately controlling information transmission as</p><p>well as energy. ‘They hold all the cards they need to construct a compre-</p><p>hensive commodity supply and media empire’ (ibid., p. 60).</p><p>One of the key factors favouring the big suppliers is the web of</p><p>direct and indirect subsidies which the industry enjoys such as the fact</p><p>that its raw material is regarded as being a free gift from nature. Only</p><p>now is it being widely realised that reserves, apart from coal, will be</p><p>exhausted sooner rather than later.</p><p>At the same time the market pays scant regard to its environmen-</p><p>tal responsibilities, especially that of driving up global warming. The</p><p>European Commission’s ExternE project has sought to quantify the</p><p>externalities. For example, it concludes that the real cost of electricity</p><p>from coal and oil is about double the current economic cost to the pro-</p><p>ducers. For gas generated electricity the shortfall is about 30 per cent.</p><p>The New Elements for the Assessment of External Costs from Energy</p><p>(NewExt) is refining the methodology to provide more accurate infor-</p><p>mation and was due to report in 2004. The results should make it possi-</p><p>ble more accurately to calculate life-cycle environmental costs.</p><p>Government claims that energy suppliers operate within the</p><p>framework</p><p>of a free market and on a level playing field is based on</p><p>flawed economics. The anomaly is that the cost–benefit system</p><p>employed here ignores the element of risk. For some reason energy is</p><p>not subjected to the normal rules of financial risk assessment in deter-</p><p>mining the market value of the commodity. Never has it been more</p><p>apparent that oil and gas are high risk commodities that can have a</p><p>powerful negative impact on the Stock Index due to price volatility.</p><p>In contrast, renewables, being relatively high capital cost but low</p><p>running cost technologies, are not nearly so affected by macro-</p><p>economic shifts such as the international price of oil or the Stock Index.</p><p>Repayment of capital and operating costs are largely fixed and so</p><p>represent a low risk. The problem is that renewables with their high</p><p>investment costs violate one of the founding laws of accountancy that</p><p>investors want a high return on capital in the short term.</p><p>This is the market situation in which renewables have to compete</p><p>and it constitutes a sharply tilted playing field in favour of the fossil fuel</p><p>industries. We have the bizarre situation that a highly subsidised, highly</p><p>polluting, high risk energy stream is stifling the almost zero risk renewable</p><p>systems that draw on solar and lunar energy and are therefore not reliant</p><p>on a continual input of an extracted fuel. This is clearly an abuse of the</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 27</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>28</p><p>term ‘free market’. If the contours of the energy playing field really were</p><p>level, then renewables would offer excellent investment opportunities.</p><p>Since it seems inevitable that renewables will have to fight their</p><p>corner in a free market for an indefinite period, then these anomalies</p><p>must be corrected if a decarbonised electricity infrastructure is to be</p><p>a reality.</p><p>Energy from rivers and seas</p><p>Energy extracted from the marine environment is, on the one hand, the</p><p>most capital intensive form of energy, but, on the other, offers the</p><p>longest-term energy certainty coupled with the highest energy density.</p><p>Energy can be derived from water according to four basic princi-</p><p>ples: first, hydroelectricity from the damming of rivers; second, from</p><p>hydrodynamics or the movement of water by virtue of tidal rise and fall,</p><p>tidal currents and waves; third, the dynamics of thermal difference;</p><p>and fourth, the extraction of hydrogen from water via electrolysis. This</p><p>chapter focuses on the first and second technologies.</p><p>Hydroelectric generation</p><p>Hydroelectric schemes which exploit height difference in the flow path</p><p>of water are the oldest method of generation from water. It involves</p><p>damming a watercourse to create the necessary pressure to drive high</p><p>speed impulse turbines. The Boulder Dam scheme in the USA was the</p><p>first large-scale project implemented in the 1930s as a means of driving</p><p>the country out of recession.</p><p>One of the first major projects to be completed after the Second</p><p>World War was the Aswan Dam scheme initiated by Colonel Nasser, the</p><p>Egyptian President. Work started in 1960 to create the huge Lake</p><p>Nasser as the storage facility and as a potential irrigation source for a</p><p>major part of the country. It cost $1 billion ($10 billion at current prices)</p><p>and began operations in 1968, delivering 2000 megawatts (MW) of power.</p><p>The project has served to illustrate some of the problems which</p><p>accompany hydroelectric schemes of this massive scale. For example,</p><p>evaporation from the lake has been much greater than anticipated, and</p><p>the country is considering reactivating storage schemes beyond its</p><p>borders. At the same time, the dam has so disrupted the flow of the</p><p>Nile that it threatens the agriculture of the delta.</p><p>A further problem is that, historically, the Nile has conveyed</p><p>millions of tonnes of silt per year, mostly soil, from the Ethiopian high-</p><p>lands. The silt, part of which used to be deposited in the Nile flood</p><p>plain, is now trapped behind the dam, a fact which is calculated to have</p><p>done irreparable damage to the fertility of the Nile valley and delta. To</p><p>compensate for the loss Egypt is now one of world’s heaviest users of</p><p>agricultural chemicals.</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 28</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>29</p><p>One of the worst drawbacks concerns saline pollution. Salts are</p><p>dissolved in river water and modern irrigation systems leave salts</p><p>behind – about one tonne per hectare. Large areas of fertile land are</p><p>being threatened by the salt which makes the ground toxic to plants</p><p>and ultimately causes it to revert to desert. There is now a project to</p><p>remove saline water from two million hectares of land at a cost which</p><p>exceeds the original price of the dam (New Scientist, pp. 28–32,</p><p>7 May 1994).</p><p>In December 1994 work commenced on the Three Gorges scheme</p><p>on the Yangtze River. The dam is two kilometres long and some</p><p>100 metres high. It has created a lake 600 kilometres long displacing</p><p>over one million people. In return the country will receive 18 000 MW of</p><p>power which is 50 per cent more than the world’s existing largest dam,</p><p>the Itaipu Dam in Paraguay. Even so, in the long term this dam will make</p><p>a relatively small impact on China’s dependency on fossil fuel. In addi-</p><p>tion, in November 1994, plans were revived to generate up to 37 000</p><p>MW along the course of Mekong River, again with drastic potential</p><p>social consequences.</p><p>With the exception of projects on the River Danube, Europe gains</p><p>most of its hydroelectricity from medium to small-scale plants. Most of</p><p>Norway’s supply is from hydro sources; in Sweden it is 50 per cent of the</p><p>total and Scotland produces 60 per cent of its electricity from non-fossil</p><p>sources, mostly hydro. According to the Department of Trade and</p><p>Industry, ‘The UK has a considerable untapped small-scale hydro</p><p>resource’ such as the discreet plant at Garnedd in Gwynedd, North</p><p>Wales. Given the right buying-in rates from the National Grid, such ven-</p><p>tures could become a highly commercial proposition.</p><p>Small-scale hydro</p><p>In small-scale projects water is usually contained at high level by a dam</p><p>or weir and led down a pipe (penstock) or channel to a generator about</p><p>50 m below to create the necessary force to drive the generator. An</p><p>intermediate technology version has been designed for developing</p><p>countries in which a standard pump is converted to a turbine and an</p><p>electric motor to a generator (New Scientist, p. 29, 29 June 1991)</p><p>(further information in Smith, P.F. (2002) ‘Small-scale hydro,’ in</p><p>Sustainability at the Cutting Edge, Ch. 10, Architectural Press).</p><p>‘Run of river’ systems</p><p>Many rivers have a flow rate in excess of 0.75 m per second which</p><p>makes them eligible to power so-called run of river generators.</p><p>The conventional method is to create a dedicated channel which</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 29</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>30</p><p>accommodates a cross-flow generator which is a modern version of a</p><p>water wheel or a ‘Kaplan’ turbine which has variable blades.</p><p>A Norwegian company, Water Power Industries (WPI), has devel-</p><p>oped a water turbine on floats that has a vertical axis rotor fitted with</p><p>blades shaped like an aircraft wing. The ‘waterfoils’ are vertical and the</p><p>flow of a river creates negative pressure which causes the wheel to</p><p>rotate (Figure 3.1). The wings are continuously adjusted by computer</p><p>monitoring to keep them at their most efficient angle. It is claimed that</p><p>the water turbine converts 50 per cent of the energy in the water to</p><p>electricity with a theoretical maximum of 59 per cent.</p><p>Assuming a steady flow of water with a velocity of 3 m/s and a regu-</p><p>larity of 96 per cent a 15 m diameter 500 kW turbine would produce</p><p>4 million kWh/year. Not only could this system capture the energy of</p><p>many rivers, it could also be situated in channels with a high tidal flow</p><p>which are too shallow for other types of tidal turbine.</p><p>Tidal energy</p><p>Tidal energy is predictable to the minute for at least the rest of the</p><p>century. Tide levels can be affected by storm surges as experienced</p><p>dramatically in the UK in 1953.</p><p>The British Isles benefit from some of the</p><p>Figure 3.1</p><p>WPI turbine (courtesy of CADDET,</p><p>issue 1/04)</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 30</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>31</p><p>greatest tidal ranges in Europe. In summary, there are at least four</p><p>technologies that can exploit the action of the tides, offering reliable</p><p>electricity in the multi-gigawatt range. They are:</p><p>● The tidal barrage</p><p>● The tidal fence or bridge</p><p>● Tidal mills or rotors</p><p>● Impoundment.</p><p>The tidal barrage</p><p>Trapping water at high tide and releasing it when there is an adequate</p><p>head is an ancient technology. A medieval tide mill is still in working</p><p>order in Woodbridge, Suffolk. In the first quarter of the twentieth cen-</p><p>tury this principle was applied to electricity generation in the feasibility</p><p>studies for a barrage across the River Severn.</p><p>Tidal power works on the principle that water is held back on the</p><p>ebb tide to provide a sufficient head of water to rotate a turbine. Dual</p><p>generation is possible if the flow tide is also exploited.</p><p>A Royal Commission was formed in 1925 to report on the potential</p><p>of the River Severn to produce energy at a competitive price. It</p><p>reported in 1933 that the scheme was viable. Since then the technology</p><p>has improved including a doubling of the size of generators. This</p><p>increases the volume of water passing through the barrage by the</p><p>square. A further study was completed in 1945 and the latest in-depth</p><p>investigation was concluded in 1981. In all cases the verdict was posi-</p><p>tive, though the last report was cautious about the cost/benefit profile</p><p>of the scheme in the context of nuclear energy. Despite this supporting</p><p>evidence the UK still shows reluctance to exploit this source of power.</p><p>Recently a discussion document produced by the Institution of Civil</p><p>Engineers stated in respect of tidal energy:</p><p>it appears illogical that so potentially abundant an option will</p><p>be deferred perpetually when the unit power costings involved</p><p>are estimated to be reasonably competitive with all alternatives</p><p>except combined cycle gas turbines.</p><p>Power generation is obviously intermittent but the spread of tide</p><p>times around the coasts helps to even out the contribution to the grid.</p><p>The only operational barrage in Europe is at La Rance, Normandy.</p><p>It is a bidirectional scheme, that is, it generates on both the flow and</p><p>ebb tides. Two-way operation is only beneficial where there is a consid-</p><p>erable tidal range and even then only during spring tides. Annual</p><p>production at La Rance is about 610 gigawatt hours (GWh). Despite its</p><p>success as a demonstration project, the French government elected to</p><p>concentrate its generation policy on nuclear power which accounts for</p><p>about 75 per cent of its capacity.</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 31</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>32</p><p>Up to now, schemes proposed in the UK have been one direc-</p><p>tional, generating only on the ebb tide. The principle is that water is</p><p>held upstream at high tide until the downstream level has fallen by at</p><p>least 2.0 metres. The upstream volume of water is supplemented by</p><p>pumping additional water from downstream on the flood tide. This is</p><p>reckoned to be more cost effective than bidirectional generation in</p><p>most situations (Figure 3.2).</p><p>The technology of barrages was transformed by the caisson tech-</p><p>niques employed in the construction of the Mulberry Harbour floated</p><p>into place after D-Day in the Second World War. It is a modular tech-</p><p>nique with turbine caissons constructed on slipways or temporary sand</p><p>islands. According to the Department of Trade and Industry’s Energy</p><p>Paper Number 60, November 1992: ‘The UK has probably the most</p><p>favourable conditions in Europe for generating electricity from the</p><p>tides.’ In fact, it has about half of all the European Union’s tidal</p><p>generating potential of approximately 105 terawatt hours per year</p><p>(TWh/y) (ETSU). The DTI report concludes:</p><p>There are several advantages arising from the construction of</p><p>tidal barrages in addition to providing a clean, non-polluting</p><p>source of energy. Tidal barrages can assist with the local</p><p>infrastructure of the region, create regional development</p><p>Figure 3.2</p><p>Basic tidal barrage</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 32</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>33</p><p>opportunities and provide protection against local flooding</p><p>within the basin during storm surge.</p><p>Around the world numerous opportunities exist to exploit tidal energy,</p><p>notably in the Bay of Fundy in Canada where there is a proposal to</p><p>generate 6400 MW. China has 500 possible sites with a total capacity of</p><p>110 000 MW.</p><p>Professor Eric Wilson, a leading tidal expert in the UK, sums up the</p><p>situation by saying that a tidal power scheme may be expensive to</p><p>build, but it is cheap to run. ‘After a time, it is a gold mine.’</p><p>In 1994 the government decided to abandon further research into</p><p>tidal barrages for a variety of reasons ranging from the ecological to the</p><p>economic. In market terms a normal market discount rate heavily</p><p>penalises a high capital cost, long life, low running cost technology. The</p><p>economic argument could be countered if the market corrections</p><p>stated earlier were to be implemented. However, another concern has</p><p>grown in stature, namely, the threat from rising sea level amplified by an</p><p>accelerating rate of storm surges.</p><p>Following the 1953 floods, it was decided that London should be</p><p>protected by a barrage. It was designed in the 1970s to last until 2030.</p><p>However, the threat from rising sea level was hardly a factor in the</p><p>1970s; now it is a major cause of concern that the barrage will be over-</p><p>whelmed by a combination of rising sea level, storm surges and</p><p>increased rainfall and river rundown well before that date. In the year</p><p>1986/87 the barrage was not closed once against tidal and river flood-</p><p>ing; in 2001 it closed 24 times. A further complication is the Thames</p><p>Gateway project which includes 120 000 new homes below sea level. If</p><p>one flood breaks through the Thames Barrier it will cost about £30 bil-</p><p>lion or roughly 2 per cent of GDP (Sir David King, Government Chief</p><p>Scientist, The Guardian, 9 January 2004). All this combines to make a</p><p>strong case for an estuary barrage that will protect both the Thames</p><p>and the Medway and, at the same time, generate multi-gigawatt power</p><p>for the capital (Figure 3.3).</p><p>One of the arguments against tidal barrages is that they would trap</p><p>pollution upstream. Since rivers are now appreciably cleaner than in the</p><p>1970s, thanks largely to EU Directives, this should not now be a factor.</p><p>The Thames is claimed to be the cleanest river in Europe, playing host</p><p>to salmon and other desirable fish species. A group of engineering</p><p>companies has renewed the argument in favour of the River Severn bar-</p><p>rage, indicating that it would meet 6 per cent of Britain’s electricity</p><p>needs whilst protecting the estuary’s coastline from flooding (New</p><p>Scientist, 25 January 2003).</p><p>The tidal fence</p><p>There is, however, an alternative to a barrage which can also deliver</p><p>massive amounts of energy at less cost/kWh, namely, the tidal fence or</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 33</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>34</p><p>bridge which has only recently come into prominence. The tidal fence</p><p>system, for example as designed by Blue Energy Canada Inc., consists</p><p>of modular shell concrete marine caissons linked to form a bridge.</p><p>Vertical axis Davis Hydro Turbines are housed between the concrete</p><p>fins. Multiple Darrieus rotors capture energy at different levels of the</p><p>tide. The rotors are 10.5 m in diameter and rotate at 25 rpm, each</p><p>turbine having a peak output of up to14 MW. They can function within</p><p>a tidal regime of at least 1.75 m. The generators are housed in the box</p><p>structure bridge element which can also serve as a highway or platform</p><p>for wind turbines (Figure 3.4).</p><p>From the ecological point of view the system has the advantage</p><p>over the barrage option of preserving the integrity of the intertidal</p><p>zones. Wading birds have nothing to fear. The slow rotation of the tur-</p><p>bines poses minimum risk to</p><p>marine life, with large marine mammals</p><p>protected by a fence with a backup of an automatic braking system</p><p>operated by sonar sensors. At the same time the system allows for the</p><p>free passage of silt.</p><p>In terms of energy density, the tidal fence outstrips other renew-</p><p>able technologies:</p><p>Wind 1000 kWh/m2</p><p>Solar (PV) 1051 kWh/m2</p><p>Wave 35–70 000 kWh/m2</p><p>Tidal fence 192 720 kWh/m2</p><p>(Source: Blue Energy Canada Inc.)</p><p>Blue Energy has designed a major installation at Dalupiri in the</p><p>Philippines. It is a four-phase project with the first phase comprising a</p><p>4 kilometre tidal fence between the islands of Dalupiri and Samar in the</p><p>Figure 3.3</p><p>River Thames flood risk zones below</p><p>5m contour and suggested barrage</p><p>5 miles</p><p>Thames</p><p>Barrier</p><p>Barrage</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 34</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>35</p><p>San Bernardino Strait. The estimated maximum capacity of the 274</p><p>turbines housed in the tidal fence is 2.2 GW guaranteeing a base daily</p><p>average of 1.1 GW. The structure is designed to withstand typhoons of</p><p>150 mph and tsunami waves of 7 m.</p><p>The potential for the UK</p><p>Many speculations have been offered regarding the ultimate generat-</p><p>ing potential of various renewable technologies. The data which are</p><p>used here have been extracted from a paper from the Tyndall Centre in</p><p>the University of Sussex, UK ‘Electricity Scenarios for 2050’ Working</p><p>paper 41, 2004, by Jim Watson which, in turn, cites data from the DTI</p><p>1999 and the RCEP 2000. The Tyndall paper suggests that the optimum</p><p>output from renewables is 136.5 GW as defined in the first of four</p><p>scenarios Many of these are intermittent and unpredictable. An excep-</p><p>tion is tidal energy which is predictable and this is where the tidal fence</p><p>comes into its own.</p><p>The British Isles offer considerable opportunities for the application</p><p>of this technology. Blue Energy has already identified the Severn estuary</p><p>as a suitable site. The Open University Renewable Energy Team has</p><p>selected 17 estuary sites suitable for medium to large-scale barrage</p><p>systems (Boyle, G. (ed.) (1996) Renewable Energy – Power for a</p><p>Sustainable Future, Oxford University Press). On the assumption that</p><p>Figure 3.4</p><p>Blue Energy tidal fence concept</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 35</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>36</p><p>these sites would be equally suitable for tidal fences, they add up to a</p><p>linear capacity of 208 km. If only half of the full estuary width were avail-</p><p>able to house turbines in each case, this would produce a peak output</p><p>of about 60 GW and a daily average of 30 GW. This is based on an</p><p>extrapolation from the Dalupiri scheme and is therefore only a rough</p><p>estimation. However, it should be enough to cause a reappraisal of the</p><p>tidal potential of the UK, especially as the cost is highly competitive.</p><p>The installed cost at present is estimated to be US$1400 per kW.</p><p>Since the output from the tidal fence is predictable and peak</p><p>output may not coincide with peak demand from the grid, it is an</p><p>appropriate system to combine with pumped storage to even out the</p><p>sinusoidal curves.</p><p>Tidal currents</p><p>The European Union has identified 42 sites around the coasts of the UK</p><p>which have sufficient tidal velocity to accommodate tidal turbines. It is</p><p>estimated that tidal stream energy has the potential to meet one quar-</p><p>ter of the electricity needs of the UK which amounts to about 18 GW.</p><p>With a load factor of 0.50, this technology would deliver 9 GW. A 1993</p><p>DTI report claimed that the Pentland Firth alone could provide 10 per</p><p>cent, or about 7 GW, of the UK’s electricity demand. However, the</p><p>greatest potential source of tidal currents is located off the islands of</p><p>Guernsey. According to Blue Energy they have the potential to gener-</p><p>ate 26 GW or more than one third of the UK’s generating capacity.</p><p>There are several technologies being researched, including the</p><p>Stingray project which exploits the tidal currents to operate</p><p>hydroplanes which oscillate with the tide to drive hydraulic motors that</p><p>generate electricity. The hydroplanes are profiled like an aircraft wing to</p><p>create ‘lift’. It is still at the development stage and its final manifestation</p><p>will operate in streams in both directions.</p><p>However, the most likely technology to succeed in the gigawatt</p><p>range are the vertical or horizontal turbines. The tidal fence vertical</p><p>turbine is claimed to be ideal for tidal streams since it has multiple</p><p>rotors which can capture tidal energy at different depths. The minimum</p><p>velocity of tidal flow to operate a tidal fence is 1.75 m/s or 3.5 knots.</p><p>The strength of the current tends to be strongest near the surface so a</p><p>vertical series of rotors could accommodate the different speeds at</p><p>various depths. An ideal site could be the Pentland Firth.</p><p>The tidal mill</p><p>Horizontal axis turbines are similar to wind turbines but water has an</p><p>energy density four times greater than air, which means that a rotor</p><p>15 m in diameter will generate as much power as a wind turbine of 60 m</p><p>diameter. They operate at a minimum velocity of about 2 m/s. Since the</p><p>tidal flow is constant, underwater turbines are subject to much less</p><p>buffeting than their wind counterparts.</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 36</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>37</p><p>Figure 3.5</p><p>Tidal stream turbines or tidal mills,</p><p>serviced above water</p><p>According to Peter Fraenkel, Director of Marine Current Turbines,</p><p>the best tidal stream sites could generate 10 MW per square kilometre.</p><p>His company has built a 300 kW demonstration turbine off the Devon</p><p>coast and has a project for a turbine farm in the megawatt range</p><p>(Figure 3.5). This company is presently investigating the opportunities</p><p>around Guernsey and Alderney.</p><p>Offshore impoundment</p><p>An alternative to estuary tidal generation is the concept of the tidal</p><p>pound. The idea is not new as mentioned earlier. The system is ideal for</p><p>situations in which there is a significant tidal range and shallow tidal</p><p>flats encountered in many coasts of the UK. The system consists of a</p><p>circular barrage built from locally sourced loose rock, sand and gravel</p><p>similar in appearance to standard coastal defences. It is divided into</p><p>three or more segments to allow for the phasing of supply to match</p><p>demand. According to Tidal Electricity Ltd, computer simulations show</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 37</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>38</p><p>that a load factor of 62 per cent can be achieved with generation possi-</p><p>ble 81 per cent of the time. Tidal pounds would be fitted with low-head</p><p>tidal generating equipment which is a reliable and mature technology.</p><p>In its Memorandum submitted to the House of Commons Select</p><p>Committee on Science and Technology this company claimed that ‘The</p><p>UK has very large tidal ranges and many suitable for sites . . . that could</p><p>conceivably generate thousands of megawatts.’ It has been estimated</p><p>that impoundment electricity could meet up to 20 per cent of UK</p><p>demand at around 15 GW. With a load factor of 0.62 this amounts to</p><p>9.3 GW.</p><p>Besides having the potential to generate substantial amounts of</p><p>electricity, tidal pounds can also provide coastal flood protection which</p><p>was an important factor in determining the viability of the first large-</p><p>scale project in the UK off the North Wales coast. In 1990 Towyn near</p><p>Rhyl experienced devastating floods. The pound will be about 9 miles</p><p>wide and 2 miles deep and located a mile offshore. It should generate</p><p>432 MW. The life expectancy of the structure is 100 years.</p><p>This is a popular holiday coast and it is expected that the project</p><p>will become an important visitor attraction. There is talk of added</p><p>attractions like a sea-life musuem and an education centre. The tidal</p><p>barrage at La Rance in Normandy attracts 600 000 visitors a year.</p><p>This is perceived as a cost-effective technology thanks in part to</p><p>the extra revenue from the Renewables Obligation Certification.</p><p>Because it is located in shallow water construction costs are much less</p><p>than for barrage systems. It is relatively unobtrusive and much kinder to</p><p>marine life than a tidal</p><p>barrage. It offers predictable power with a load</p><p>factor which is significantly better than, for example, wind power.</p><p>In total the potential capacity of the various technologies that</p><p>exploit the tides around Britain is in the region of 65 GW. The variation</p><p>in high water times around the coasts coupled with pumped storage</p><p>help to even out the peaks and troughs of generation before any</p><p>account is taken of the range of other technologies.</p><p>Wave power</p><p>Wave power is regarded as a reliable power source and has been esti-</p><p>mated as being capable of meeting 25 per cent or 18 GW of total UK</p><p>demand with a load factor of 0.50, giving a reliable output of about</p><p>9 GW, and is already contributing 500 kW to the grid.</p><p>The World Energy Council estimates that wave power could meet</p><p>10 per cent of world electricity demand.</p><p>The most favoured system uses the motion of the waves to create</p><p>an oscillating column of water in a closed chamber which compresses</p><p>air which, in turn, drives a turbine. There are both inshore and offshore</p><p>versions either in operation or projected. The first inshore version</p><p>in the UK was positioned on an inlet in the Scottish Isle of Islay</p><p>(Figure 3.6).</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 38</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>39</p><p>It was designed by Queen’s University, Belfast, and has an output</p><p>of 75 kW which is fed directly to the grid. The success of this pilot</p><p>project justified the construction of a full-scale version which is now in</p><p>operation.</p><p>A 25 metre slit has been cut into the cliffs facing the north Atlantic</p><p>at Portnahaven to accommodate a wave chamber inclined at 45</p><p>degrees to the water. Two turbines are driven by positive pressure as air</p><p>is compressed by incoming waves, and negative pressure as the reced-</p><p>ing waves pull air into the chamber. The rather clever Wells turbine</p><p>rotates in one direction in either situation. It is rated at 500 kW which is</p><p>enough to power 200 island homes.</p><p>Currently under test in the Orkneys is a snake-like device called</p><p>Pelamis which consists of five flexibly linked floating cylinders, each of</p><p>3.5 m diameter. The joints between the cylinders contain pumps which</p><p>force oil through hydraulic electricity generators in response to the rise</p><p>and fall of the waves. It is estimated to produce 750 kW of electricity.</p><p>The manufacturer, Ocean Power Devices (OPD), claims that a 30 MW</p><p>wave farm covering a square kilometre of sea would provide power for</p><p>20 000 homes. Twenty such farms would provide enough electricity for</p><p>a city the size of Edinburgh.</p><p>Like Scotland, Norway enjoys an enormous potential for extracting</p><p>energy from waves. As far back as 1986 a demonstration ocean wave</p><p>power plant was built based on the ‘Tapchan’ concept (Figure 3.7). This</p><p>consists of a 60 m long tapering channel built within an inlet to the sea.</p><p>The narrowing channel has the effect of amplifying the wave height.</p><p>This lifts the sea water about 4 m depositing it into a 7500 m2 reservoir.</p><p>The head of water is sufficient to operate a conventional hydroelectric</p><p>power plant with a capacity of 370 kW.</p><p>A large-scale version of this concept is under construction on</p><p>the south coast of Java in association with the Norwegians. The plant</p><p>Figure 3.6</p><p>Principle of the Isle of Islay OWC</p><p>wave generator</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 39</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>40</p><p>will have a capacity of 1.1 MW. As a system this has numerous</p><p>advantages:</p><p>● The conversion device is passive with no moving parts in the</p><p>open sea.</p><p>● The Tapchan plant is able to cope with extremes of weather.</p><p>● The main mechanical components are standard products of proven</p><p>reliability.</p><p>● Maintenance costs are very low.</p><p>● The plant is totally pollution free.</p><p>● It is unobtrusive.</p><p>● It will produce cheap electricity for remote islands.</p><p>The total for the three tide and wave technologies, taking account</p><p>of load factors, could come to about 74 GW.</p><p>If we substitute these figures for the quantities indicated in Jim</p><p>Watson’s paper (op. cit.) for wave, tidal stream and tidal barrage of</p><p>around 16 GW, and add the remaining renewable technologies from</p><p>this source amounting to 119 GW taking account of load factors, the</p><p>total comes to about 193 GW. This amounts to more than twice the</p><p>present electricity generating capacity of the UK.</p><p>Figure 3.7</p><p>Wave elevator system, the ‘Tapchan’</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 40</p><p>RENEWABLE TECHNOLOGIES – THE MARINE ENVIRONMENT</p><p>41</p><p>The other part of the equation is the demand side and Watson’s</p><p>scenarios include a reduction in electricity demand of up to one third.</p><p>Assuming significant gains in energy efficiency, even if half the natural</p><p>assets of the UK are exploited to produce carbon-free electricity, this</p><p>leaves an appreciable margin of supply over demand. The logical use</p><p>for this surplus capacity is to maximise pumped storage and to create</p><p>hydrogen from electrolysis. This could provide further backup capacity</p><p>from megawatt grid connected fuel cells in addition to fuelling the</p><p>growing population of hydrogen powered road vehicles expected over</p><p>the next decade.</p><p>It has been estimated that converting transport to hydrogen would</p><p>require 143 GW of electrical power to extract hydrogen from water via</p><p>electrolysis.</p><p>There is no doubt that the UK has the natural assets to enable it to</p><p>be fossil fuel free in meeting its electricity needs by 2030. However, this</p><p>would require an immediate policy decision by the government to</p><p>make a quantum leap in its investment in renewable technologies,</p><p>especially the range of opportunities offered by the tides. Tidal energy</p><p>could more than fill the void in supply left by the demise of nuclear.</p><p>What is needed is cross-party political support so that the subject of</p><p>renewable energy is removed from the cut and thrust of politics.</p><p>In his ‘green speech’ in March 2003 Prime Minister Blair stated that</p><p>he wanted Britain ‘to be a leading player in this green industrial revolu-</p><p>tion . . . We have many strengths to draw on. Some of the best marine</p><p>renewable resources in the world – offshore wind, wave energy and</p><p>tidal power.’ This chapter suggests a ‘road map’ that would enable</p><p>actions to be matched to words.</p><p>AIAC-Ch03.qxd 03/29/2005 17:26 Page 41</p><p>Whilst Chapter 3 has focused on marine renewable technologies with</p><p>special emphasis on the UK, this chapter scans more widely to include</p><p>the opportunities that occur in different climates.</p><p>The sun is the primary source of renewable energy. Besides offer-</p><p>ing a direct source of energy, it drives the Earth’s climate creating</p><p>opportunities to draw energy from wind, waves, tides (together with the</p><p>moon) and a host of biological sources. It is particularly appropriate as</p><p>an energy source for buildings. The following paragraphs are by way of</p><p>an introduction. More detailed explanations will appear later.</p><p>Passive solar energy</p><p>Advocates of passive solar design have been around for many decades</p><p>and the prize-winning schemes in a European competition for passive</p><p>solar housing mounted in 1980 show that the technology has not</p><p>advanced significantly since that time. However, the intensification of</p><p>the global warming debate has led to increasing pressure to design</p><p>buildings which make maximum use of free solar gains for heating,</p><p>cooling and lighting. This will be considered in detail in later chapters.</p><p>Because it displaces the use of fossil fuel it is estimated that</p><p>passive solar design could lead to a reduction in carbon dioxide (CO2)</p><p>amounting to 3.5 million tonnes per year in the UK alone by the year</p><p>2025 (DOE Energy Paper 60).</p><p>Active solar</p><p>This term refers to the conversion of solar energy into some form of</p><p>usable heat. In temperate climates the most practical application of</p><p>solar radiation is to exploit the heat of the sun to supplement a</p><p>conventional heating system.</p><p>Communities in a situation where there are high levels of insolation</p><p>can benefit from technologies not viable in temperate climes.</p><p>42</p><p>Renewable technologies –</p><p>the wider spectrum</p><p>Chapter</p><p>Four</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 42</p><p>RENEWABLE TECHNOLOGIES – THE WIDER SPECTRUM</p><p>43</p><p>Solar thermal electricity</p><p>In areas where there is substantial sunshine, solar energy can be used to</p><p>generate electricity in a number of ways. One method which has been</p><p>successfully demonstrated is the solar chimney.</p><p>Designed primarily for desert locations it consists of a tall column</p><p>surrounded by a glass solar collector. In effect it is a chimney sur-</p><p>rounded by a huge solar collector or greenhouse. The air is heated by</p><p>the circular greenhouse and drawn through the chimney which acts as a</p><p>thermal accelerator. Within the chimney are one or more vertical axis</p><p>turbines. A prototype has been built in Manzanares, Spain, with a</p><p>195 metre tower served by a greenhouse collector 240 metres in diam-</p><p>eter. The collector warms the air by around 17�C creating an updraught</p><p>of 12 metres per second giving an output of 50 kilowatts (Figure 4.1).</p><p>The project has demonstrated the viability of the principle and plans</p><p>are being drawn up for a giant version in Mildura, Australia. The eco-</p><p>nomics suggest that the tower would produce about 650 gigawatt hours</p><p>per year or enough to serve a population of 70 000. The tower will be</p><p>1000 metres high with a solar collector of glass and plastic 7 kilometres</p><p>across. The updraught would be about 15 metres per second or 54 km/hr</p><p>and will drive 32 turbines at the base. The outer areas of the collector,</p><p>where the temperature would be near the ambient level, would be used</p><p>to grow food. The plant would operate over night by using daytime heat</p><p>to warm underground water pipes connected to an insulated chamber,</p><p>returning heat to the surface of the collector during the night. The</p><p>scheme would carry low maintenance costs and would have a life</p><p>expectancy of 100 years. Construction of the tower will consume an esti-</p><p>mated 700 000 m3 of high strength concrete. A lookout gallery at the top</p><p>of the tower promises to be a not-to-be-missed tourist attraction (see</p><p>New Scientist, 31 July 2004, pp. 42–45).</p><p>The Almeria region of Spain is the sunniest location in Europe,</p><p>achieving about 3000 hours of sun a year. This is why the area has been</p><p>chosen to demonstrate another technology for producing electricity</p><p>called the SolAir project. In essence it produces superheated steam to</p><p>drive a turbine.</p><p>The idea has been made possible by the development of ceramics</p><p>that can tolerate high temperatures. At ground level 300 large mirrors</p><p>or heliostats each 70 m2 track the passage of the sun and focus its rays</p><p>on a silicon carbide ceramic heat absorber. The surface of the absorber</p><p>reaches 1000�C. Air blown through its honeycomb structure reaches</p><p>680�C. The hot air travels down the absorber tower to a heat exchanger</p><p>where it generates steam to drive a conventional turbine. The system</p><p>produces up to 1 megawatt of electricity. The ceramic is also able to</p><p>store heat to compensate for cloudy conditions.</p><p>According to the Spanish Ministry of Science: ‘In five to ten years’</p><p>time there should be several plants across Europe, each 15 to 20 times</p><p>larger than the demonstration plant and together generating hundreds</p><p>Figure 4.1</p><p>Solar chimney generator</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 43</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>44</p><p>Figure 4.2</p><p>Solar concentrator, Abilene, Texas</p><p>(courtesy of CADDET)</p><p>of megawatts’ (New Scientist,‘Power of the midday sun’, 10 April 2004).</p><p>At current prices it is expected to produce electricity at one third the</p><p>price of photovoltaics. Plans are already in place to locate these plants</p><p>along the Algerian coast to export electricity to Europe. Egypt is also</p><p>warming to the possibility of this new export opportunity.</p><p>The parabolic solar thermal concentrator</p><p>This is another option for sun-drenched locations which focuses the</p><p>radiation to produce intense heat – up to 800�C. A version in the United</p><p>States links this to a unique helium-based Stirling engine. The concen-</p><p>trator mirrors produce about 30 kW of reflective power to the heat pipe</p><p>receiver which is linked to the engine. The engine operates on the basis</p><p>that the heat vaporises liquid sodium in its receiver at the focal point of</p><p>the dish. Condensation of the sodium on the heater tubes raises the</p><p>temperature of an internal helium circuit. The expanding helium drives</p><p>pistons which in turn drive an alternator to produce electricity</p><p>(Figure 4.2).</p><p>An alternative solar concentrator built by the Australian National</p><p>University uses a computer to enable it to track the sun with extreme</p><p>accuracy. This system produces superheated steam in a solar boiler at</p><p>the focal point. The steam is piped to a four cylinder expansion engine</p><p>that drives a 65 kVA generator.</p><p>One spin-off from this technology is a demonstration scheme which</p><p>has attached 18 solar thermal power dishes to an existing coal fired</p><p>steam turbine power station producing the equivalent of 2.6 MW for the</p><p>grid which saves some 4500 tonnes/year of CO2. The development</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 44</p><p>RENEWABLE TECHNOLOGIES – THE WIDER SPECTRUM</p><p>45</p><p>potential is to use the waste heat from the system for co-generation.</p><p>In hot dry climates an ideal application for this system is in desalination.</p><p>A variation of this principle is the SunDish Tower System of STM</p><p>Power in the USA, which uses a unique type of Stirling engine with inte-</p><p>gral electricity generation within the sealed chamber (see p. 91).</p><p>Photovoltaics</p><p>The amount of energy supplied to the Earth by the sun is five orders of</p><p>magnitude larger than the energy needed to sustain modern civilisa-</p><p>tion. One of the most promising systems for converting this solar radia-</p><p>tion into usable energy is the photovoltaic (PV) cell. PV materials</p><p>generate direct electrical current (DC) when exposed to light. The</p><p>uniqueness of PV generation is that it is based on the ‘photoelectric</p><p>quantum effect in semi-conductors’ which means it has no moving parts</p><p>and requires minimum maintenance. Silicon is, at present, the domi-</p><p>nant PV material which is deposited on a suitable substrate such as</p><p>glass. Its disadvantages are that it is expensive; it is, as yet, capable of</p><p>only a relatively low output per unit of area, and, of course, only oper-</p><p>ates during daylight hours and is therefore subject to fluctuation in</p><p>output due to diurnal, climate and seasonal variation. As it produces</p><p>DC current, for most purposes this has to be changed to alternating</p><p>current (AC) by means of an inverter.</p><p>Growth in the manufacture of PVs has been accelerating at an</p><p>extraordinary pace. In 2002 it was 56 per cent in Europe and 46 per cent</p><p>in Japan, greater than in 2001. We are now seeing the emergence of</p><p>large plants producing PVs on an industrial scale, that is, over 200 MW</p><p>per year. The result is that unit costs have almost halved between 1996</p><p>and 2002. Significant further cost reductions are confidently predicted</p><p>coupled with steady improvements in efficiency.</p><p>One application of PVs is its potential radically to improve the</p><p>quality of life in the rural regions of developing countries. This is</p><p>certainly one area on which the industrialised countries should focus</p><p>capital and technology transfer to less and least developed countries.</p><p>Already rural medical facilities are being served by PV arrays, for example</p><p>the rural hospital at Dire’ in Mali. On a smaller scale, compact and</p><p>mobile PV arrays can operate refigerators and water pumps.</p><p>PV technology will be considered further in Chapter 7.</p><p>Wind power</p><p>Wind is a by-product of solar power and, as with the tides, wind power</p><p>has been exploited as an energy source for over 2000 years. Whilst it is</p><p>an intermittent source of power, in certain countries such as the UK and</p><p>Denmark, wind is a major resource. The UK has the best wind regime in</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 45</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>46</p><p>Europe but still has a considerable distance to go to meet its target of</p><p>8 per cent of total demand for wind generation by 2010.</p><p>There are two basic types of wind generator: horizontal and verti-</p><p>cal axis. The great majority of generators in operation are of the</p><p>hori-</p><p>zontal axis type with either two or three blades. Vertical axis machines</p><p>such as the helical turbine are particularly appropriate for siting on</p><p>buildings.</p><p>Whilst the technology is well developed and robust, there are</p><p>drawbacks to this form of power. The most frequently cited are:</p><p>● Often the most advantageous onshore sites are also places of par-</p><p>ticular natural beauty.</p><p>● Such sites are often some distance from the grid and centres of</p><p>population.</p><p>● At full revolutions the noise they create can be intrusive.</p><p>● They have been implicated in interfering with television reception.</p><p>● They are a particular hazard to birds and have attracted severe</p><p>criticism from the Royal Society for the Protection of Birds (RSPB).</p><p>● They are said to interfere with radar signals and have raised concerns</p><p>in the Ministry of Defence.</p><p>● The output is unpredictable.</p><p>On the other hand, they are relatively cheap and in the UK can generate</p><p>electricity at a cost of 7 p/kWh assuming a 20-year life and a 15 per cent</p><p>rate of return (Energy Paper 60). Of course the required rate of return is</p><p>a contentious issue, as mentioned earlier, since it takes no account of</p><p>the avoided cost to both the lower and upper atmosphere with all its</p><p>global warming implications.</p><p>Several of the negative factors can be overcome by locating the</p><p>generators offshore. The conventional method is to fix the machine to</p><p>the sea bed. The UK government announced in 2003 that it is planning</p><p>a 6000 MW expansion of offshore wind generation by 2010. At that</p><p>time the existing installed capacity was 570 MW. The target is, to say</p><p>the least, ambitious but necessary if wind is to supply its overall share</p><p>of 8 GW towards the declared 10 GW target for renewables by 2010.</p><p>Two major offshore wind farms have already been installed off the coast</p><p>of North Wales near Rhyl and Scroby Sands off the Norfolk coast.</p><p>Expert opinion has it that, with the best wind regime in Europe,</p><p>Britain has the capacity to generate three times as much electricity by</p><p>windpower as it consumes. It is estimated that it would be feasible to</p><p>produce 55 TWh/y by wind generation, the majority of which would be</p><p>located in Scotland. However, in practice there is a limit to the amount</p><p>of unpredictable power the grid can accept and the realistic limit is said</p><p>to be 32 TWh/y.</p><p>In addition to offshore sites, as sea levels rise and storm intensities</p><p>increase, some exposed estuaries will need hard barrages which could</p><p>serve as tidal generators as well as affording ideal sites for wind turbines.</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 46</p><p>RENEWABLE TECHNOLOGIES – THE WIDER SPECTRUM</p><p>47</p><p>Harbour walls also have a highly favourable wind regime and therefore</p><p>offer excellent sites, as demonstrated by Blyth in Northumberland.</p><p>There is a growing market for domestic scale wind power and sev-</p><p>eral firms are producing small-scale generators with an output ranging</p><p>from 3.5 to 22 kW which could be installed on buildings. These turbines</p><p>will be considered in more detail in Chapter 9.</p><p>Biomass and waste utilisation</p><p>The term ‘biomass’ refers to the concept either of growing plants as a</p><p>source of energy or using plant waste such as that obtained from man-</p><p>aged woodlands or saw mills. It is estimated that the amount of fixed</p><p>carbon in land plants is roughly equivalent to that which is contained in</p><p>recoverable fossil fuels (The World Directory of Renewable Energy</p><p>(2003), p. 42, James and James, London). Whilst the economics of con-</p><p>verting biomass and waste to energy are still somewhat uncompetitive</p><p>compared with fossil fuels, the pressure to reduce CO2 emissions com-</p><p>bined with ‘polluter pays’ principles and landfill taxes for waste will</p><p>change the economic balance in the medium term. Within the</p><p>European Union the ‘set-aside’ land regulations have created an</p><p>opportunity to put the land to use to create bio-fuels.</p><p>Increasing environmental pressures are stimulating the growth of</p><p>waste to energy schemes. An ever increasing body of regulations is</p><p>limiting the scope to dispose of waste in traditional ways. Sorted munici-</p><p>pal solid waste (MSW) represents the greatest untapped energy</p><p>resource for which conversion technology already exists.</p><p>There are three ways in which biomass and waste can be converted</p><p>into energy:</p><p>● Direct combustion</p><p>● Conversion to biogas</p><p>● Conversion to liquid fuel.</p><p>Direct combustion</p><p>Direct combustion represents the greatest use of biomass for fuel</p><p>worldwide. Sweden and Austria generate a significant proportion of</p><p>their electricity by burning the residue from timber processing. The</p><p>direct burning of municipal waste is becoming increasingly popular.</p><p>However, the presence of heavy metals in such waste poses a danger</p><p>from toxic emissions including, it is claimed, dioxins. In the UK there is</p><p>a major plant in Lewisham in southeast London, capable of generating</p><p>30 MW of electricity (DTI Renewable Energy Case Study: ‘Energy from</p><p>Municipal Solid Waste’, SELCHP, Lewisham). Sheffield has one of the</p><p>most extensive systems using Finnish technology and providing the city</p><p>centre with heat and supplying power to the grid.</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 47</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>48</p><p>The direct burning of rapid rotation crops is a technology which</p><p>is said to be CO2 efficient since the carbon emissions balance the car-</p><p>bon fixed during growth. However, a paper published in 1980 by</p><p>Michael Allaby and James Lovelock drew attention to the risks to health</p><p>associated with wood burning (‘Wood stoves: the trendy pollutant’, New</p><p>Scientist, 13 November 1980). The authors identified nine compounds</p><p>found in wood smoke that are known or suspected carcinogens.</p><p>The first UK commercial biomass electricity generating plant fuelled</p><p>by poultry litter (a mixture of straw, wood and poultry droppings) was</p><p>built at Eye, Suffolk. It has a capacity of 12.5 MW and uses about half the</p><p>total of litter from broiler farms in the county. It is claimed to reduce</p><p>greenhouse gas emissions by 70 per cent compared with coal-fired</p><p>plants. It also eliminates the production of the powerful greenhouse gas</p><p>methane and nitrates which enter the water supply. A much larger bio-</p><p>mass plant is in operation in Thetford which consumes 450 000 tonnes</p><p>per year of poultry litter to deliver 38.5 MW of power. Its environmental</p><p>benefit is that it reduces net CO2 emission by recycling carbon rather</p><p>than producing new CO2. It also eliminates methane emissions from</p><p>stored poultry litter.</p><p>In the UK about 1.8 million tonnes of poultry waste and 12 million</p><p>tonnes of livestock slurry are produced annually. This offers substantial</p><p>biomass-to-energy conversion opportunities either as direct combus-</p><p>tion or by using anaerobic digestion technologies.</p><p>Biogas</p><p>The most straightforward exploitation of biogas involves the tapping of</p><p>methane produced by decaying waste material in landfill sites. This has</p><p>a considerable environmental benefit since it burns the methane which</p><p>would otherwise add more intensively to the greenhouse problem. Gas</p><p>is collected using a series of vertical collection wells connected to a</p><p>blower which draws gas from the waste. Foreign matter is extracted</p><p>and the gas then fed to a conventional engine which drives a generator.</p><p>The engine would use ‘lean-burn’ technology to minimise emissions of</p><p>nitrogen oxides and carbon monoxide (Power generation from landfill</p><p>gas; Cuxton, UK, DTI Renewable Energy Case Study 2).</p><p>Anaerobic digestion uses wet waste products to produce energy in</p><p>the form of methane-rich biogas. The process, which involves a fer-</p><p>mentation stage, takes place in large heated tanks at either 30–35�C or</p><p>55�C during which 60 per cent of the organic material is converted to</p><p>biogas. The liquids and solids which remain after digestion are used as</p><p>fertilisers and soil conditioners.</p><p>The methane-rich gas is most effectively employed to fuel combined</p><p>heat and power (CHP) schemes which is how the technology has been</p><p>employed on an ambitious scale in Denmark. Here co-operative ventures</p><p>receiving waste from all the farms in a viable</p><p>collection area are combined</p><p>with non-toxic industrial and food waste to fuel extensive CHP networks.</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 48</p><p>RENEWABLE TECHNOLOGIES – THE WIDER SPECTRUM</p><p>49</p><p>The next logical step is to employ the technology to exploit the</p><p>energy potential of human sewage on a national scale, thus alleviating</p><p>two problems simultaneously.</p><p>One of the most promising technologies to have developed in</p><p>recent years involves the gasification of municipal waste. Non-solid</p><p>waste is superheated to produce methane which then fuels a steam tur-</p><p>bine. The process involves heat recovery so that there is a commercial</p><p>net energy gain in the process. The unit price of electricity generated</p><p>by this process can be offset by the avoided costs of landfill disposal</p><p>together with the taxes this incurs.</p><p>Liquid fuels</p><p>The advantage of converting crops to liquid fuel is that it is portable and</p><p>therefore suitable for vehicles. The damage to health from low-level</p><p>pollution is becoming increasingly a matter of concern and overtaking</p><p>the greenhouse factor as the driving force behind the development of</p><p>minimum polluting vehicles.</p><p>The world’s largest experiment in alternative fuel has been taking</p><p>place in Brazil since 1975. Ethanol produced from sugar cane powers</p><p>about 4 million cars in that country. It produces fewer pollutants than</p><p>petrol and is a net zero carbon fuel. A problem for Brazil was that world</p><p>energy prices had fallen to such an extent as to make ethanol uneco-</p><p>nomic without government subsidy. There was a danger that the</p><p>ethanol programme would collapse under the weight of market forces.</p><p>However, improvements in the rate of growth per hectare combined</p><p>with greater use in the generation of power for the grid together with</p><p>steeply rising oil prices could save the situation.</p><p>Another use for ethanol is in the creation of hydrogen for fuel cells.</p><p>A mixture of ethanol, water and air is fed to a reactor which is a compact</p><p>fuel cell hydrogen generator. The mixture is heated and passed</p><p>through two catalysts. About half the gas emerging from the process is</p><p>hydrogen. It has the potential to produce electricity for the grid using</p><p>biowaste from agriculture and dedicated energy crops.</p><p>Geothermal energy</p><p>Natural hot water has been used since at least the nineteenth century</p><p>for industrial purposes. The first geothermal power station was built in</p><p>Italy in 1913 and produced 250 kW. Now 22 countries generate electric-</p><p>ity using geothermal energy. However, its conversion efficiency is low,</p><p>ranging from 5 to 20 per cent. Much greater efficiency is realised with</p><p>the direct use of this energy for space or district heating. Then it rises to</p><p>between 50 and 70 per cent.</p><p>Alternatively, hot dry rocks can supply energy by means of bore-</p><p>holes through which water is pumped and returned to the surface to</p><p>provide space heating. This is known as the borehole heat exchanger</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 49</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>50</p><p>system (BHE). In Switzerland, for example, it is a major source of energy</p><p>with one borehole for every 300 persons.</p><p>If much more heat is required from the BHE in winter than can flow</p><p>back in summer, a means must be found to regenerate the ground by</p><p>artificial means. This opens the way for the dual use of BHEs – heat</p><p>collection in winter and heat rejection in summer. With buildings they</p><p>can therefore be used for both heating and cooling.</p><p>The UK was one of the leaders in the field of hot dry rocks geothermal</p><p>research. However, efforts to achieve a commercial return on this energy</p><p>route have proved unsuccessful and further work has been abandoned.</p><p>Hydrogen</p><p>This is widely seen as the fuel of the future and will come in for further</p><p>consideration in Chapter 13. It is non-polluting, has a reasonable</p><p>calorific value, and can be safely stored. Off-peak or PV electricity can</p><p>be used to split water via an electrolyser to make hydrogen. This can be</p><p>used as a direct fuel or to make electricity through the chemical reac-</p><p>tion in a fuel cell (see p. 90).</p><p>Nuclear power</p><p>There are some who would place nuclear generation in the renewables</p><p>category. Whilst there may be as yet no known limit to the availability of</p><p>fuel for fission nuclear power stations, the problems of security, decom-</p><p>missioning and waste disposal remain largely unsolved. The UK’s</p><p>radioactive waste tally currently stands at 10 000 tonnes. For these rea-</p><p>sons, in this context, nuclear power will remain an unsustainable energy</p><p>source until its problems are solved in a way that will not impose a</p><p>burden on future generations. Those opposed to nuclear generation</p><p>have been encouraged by the decision of the UK government to aban-</p><p>don plans to construct two further pressurised water plants. The Energy</p><p>White Paper of 2002 deferred a decision on nuclear expansion until</p><p>2005 on the grounds that it would then review the potential of renew-</p><p>able technologies to fill the impending energy gap. At the present rate</p><p>of progress it would seem that this is a forlorn hope even though stud-</p><p>ies have shown that renewables can generate at least twice the capac-</p><p>ity needed for the UK as stated earlier.</p><p>Events of 2002 have illustrated how international terrorism has</p><p>reached new heights of sophistication. Some consider that it would be</p><p>folly to construct a new generation of tempting targets.</p><p>There has been progress on the development of nuclear fusion – the</p><p>power source that replicates the energy of the sun. The principle is that a</p><p>mix of hydrogen isotopes is heated to 100 million degrees which causes</p><p>their nuclei to fuse producing helium and massive amounts of energy.</p><p>Powerful elecromagnetic rings called tokamaks (like a doughnut) are able</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 50</p><p>RENEWABLE TECHNOLOGIES – THE WIDER SPECTRUM</p><p>51</p><p>to store the superheated plasmas. So far the problem has been that it has</p><p>taken more energy to heat the gas to fusion temperature than is pro-</p><p>duced by the reaction. There has also been a problem of maintaining the</p><p>high temperatures. However, the UK’s fusion laboratory at Culham has</p><p>achieved breakeven between energy input and output. A Japanese facil-</p><p>ity has achieved the same result.</p><p>Designs have been produced for the next generation of reactor</p><p>by a consortium of the European Union, Japan and Russia – the</p><p>International Tokamak Experimental Reactor (ITER). It is predicted to</p><p>produce ten times as much power as it consumes. According to Sir</p><p>David King, UK Chief Government Scientist, we could have commercial</p><p>fusion electricity within 30 years. ‘If successful, it could be the world’s</p><p>most important energy source over the next millennium’ (New Scientist,</p><p>10 April 2004, p. 20). Unlike the present day nuclear fission reactor,</p><p>fusion reactors will not produce masses of highly radioactive waste stay-</p><p>ing a hazard for 250 000 years.</p><p>Those concerned about a new generation of nuclear fission reac-</p><p>tors should note the prediction in a Royal Commission report of 2000</p><p>that, if current trends continue, including the present rate of installing</p><p>renewable technologies, then by 2050 the country will need the equiva-</p><p>lent of 46 of the latest Sizewell B type nuclear reactors to meet demand</p><p>(Energy – The Changing Climate, Royal Commission on Environmental</p><p>Pollution Report, 2000).</p><p>AIAC-Ch04.qxd 03/29/2005 17:27 Page 51</p><p>52</p><p>Chapter</p><p>Five</p><p>Low energy techniques for</p><p>housing</p><p>It would appear that, for the industrialised countries, the best chance</p><p>of rescue lies with the built environment because buildings in use or</p><p>in the course of erection are the biggest single indirect source of</p><p>carbon emissions generated by burning fossil fuels, accounting for over</p><p>50 per cent of total emissions. If you add the transport costs generated</p><p>by buildings the UK government estimate is 75 per cent. It is the built envi-</p><p>ronment which is the sector that can most easily accommodate fairly rapid</p><p>change without pain. In fact, upgrading buildings, especially the lower</p><p>end of the housing stock, creates a cluster of interlocking virtuous circles.</p><p>Construction</p><p>systems</p><p>Having considered the challenge presented by global warming and the</p><p>opportunities to generate fossil-free energy, it is now time to consider</p><p>how the demand side of the energy equation can respond to that chal-</p><p>lenge. The built environment is the greatest sectoral consumer of</p><p>energy and, within that sector, housing is in pole position accounting</p><p>for 28 per cent of all UK carbon dioxide (CO2) emissions.</p><p>In the UK housing has traditionally been of masonry and since the</p><p>early 1920s this has largely been of cavity construction. The purpose</p><p>was to ensure that a saturated external leaf would have no physical</p><p>contact with the inner leaf apart from wall ties and that water would be</p><p>discharged through weep holes at the damp-proof course level. Since</p><p>the introduction of thermal regulations, initially deemed necessary to</p><p>conserve energy rather than the planet, it has been common practice</p><p>to introduce insulation into the cavity. For a long time it was mandatory</p><p>to preserve a space within the cavity and a long rearguard battle</p><p>was fought by the traditionalists to preserve this ‘sacred space’.</p><p>Defeat was finally conceded when some extensive research by the</p><p>Building Research Establishment found that there was no greater risk of</p><p>damp penetration with filled cavities and in fact damp through</p><p>condensation was reduced.</p><p>Solid masonry walls with external insulation are common practice in</p><p>continental Europe and are beginning to make an appearance in the UK.</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 52</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>53</p><p>In Cornwall the Penwith Housing Association has built apartments of</p><p>this construction on the sea front, perhaps the most challenging of</p><p>situations.</p><p>The advantages of masonry construction are:</p><p>● It is a tried and tested technology familiar to house building</p><p>companies of all sizes.</p><p>● It is durable and generally risk free as regards catastrophic failure –</p><p>though not entirely. A few years ago the entire outer leaf of a</p><p>university building in Plymouth collapsed due to the fact that the</p><p>wall ties had corroded.</p><p>● Exposed brickwork is a low maintenance system; maintenance</p><p>demands rise considerably if it receives a rendered finish.</p><p>● From the energy efficiency point of view, masonry homes have a</p><p>relatively high thermal mass which is considerably improved if there</p><p>are high density masonry internal walls and concrete floors.</p><p>Framed construction</p><p>Volume house builders are increasingly resorting to timber-framed</p><p>construction with a brick outer skin, making them appear identical</p><p>to full masonry construction. The attraction is the speed of erection</p><p>especially when elements are fabricated off site. However, there is an</p><p>unfortunate history behind this system due to shortcomings in quality</p><p>control. This can apply to timber which has not been adequately cured</p><p>or seasoned. Framed buildings need to have a vapour barrier to walls</p><p>as well as roofs. With timber framing it is difficult to avoid piercing</p><p>the barrier. There can also be problems achieving internal fixings. For the</p><p>purist, the ultimate criticism is that it is illogical to have a framed building</p><p>clad in masonry when it cries out for a panel, boarded, slate or tile hung</p><p>external finish.</p><p>Pressed steel frames for homes are now being vigorously pro-</p><p>moted by the steel industry. The selling point is again speed of erection</p><p>but with the added benefit of a guaranteed quality in terms of strength</p><p>and durability of the material.</p><p>From the energy point of view, framed buildings can accommo-</p><p>date high levels of insulation but have relatively poor thermal mass</p><p>unless this is provided by floors and internal walls.</p><p>Innovative techniques</p><p>Permanent Insulation Formwork Systems (PIFS) are beginning to make</p><p>an appearance in Britain. The principle behind PIFS is the use of preci-</p><p>sion moulded interlocking hollow blocks made from an insulation</p><p>material, usually expanded polystyrene. They can be rapidly assembled</p><p>on site and then filled with pump grade concrete. When the concrete</p><p>has set the result is a highly insulated wall ready for the installation of</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 53</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>54</p><p>services and internal and exterior finishes. They can achieve a U-value</p><p>as low as 0.11 W/m2K. Above three storeys the addition of steel rein-</p><p>forcement is necessary.</p><p>The advantages of this system are:</p><p>● Design flexibility; almost any plan shape is possible.</p><p>● Ease and speed of erection; skill requirements are modest which is</p><p>why it has proved popular with the self-build sector. Experienced</p><p>erectors can achieve 5 m2 per man hour for erection and placement</p><p>of concrete.</p><p>● The finished product has high structural strength together with</p><p>considerable thermal mass and high insulation value.</p><p>Solar design</p><p>Passive solar design</p><p>Since the sun drives every aspect of the climate it is logical to describe</p><p>the techniques adopted in buildings to take advantage of this fact as</p><p>‘solar design’. The most basic response is referred to as ‘passive solar</p><p>design’. In this case buildings are designed to take full advantage of</p><p>solar gain without any intermediate operations.</p><p>Access to solar radiation is determined by a number of conditions:</p><p>● the sun’s position relative to the principal facades of the building</p><p>(solar altitude and azimuth);</p><p>● site orientation and slope;</p><p>● existing obstructions on the site;</p><p>● potential for overshadowing from obstructions outside the site</p><p>boundary.</p><p>One of the methods by which solar access can be evaluated is the</p><p>use of some form of sun chart. Most often used is the stereographic sun</p><p>chart (Figure 5.1) in which a series of radiating lines and concentric</p><p>circles allow the position of nearby obstructions to insolation, such as</p><p>other buildings, to be plotted. On the same chart a series of sun path</p><p>trajectories are also drawn (usually one arc for the 21st day of each</p><p>month); also marked are the times of the day. The intersection of the</p><p>obstructions’ outlines and the solar trajectories indicate times of transi-</p><p>tion between sunlight and shade. Normally a different chart is constructed</p><p>for use at different latitudes (at about two degree intervals).</p><p>Sunlight and shade patterns cast by the proposed building itself</p><p>should also be considered. Graphical and computer prediction tech-</p><p>niques may be employed as well as techniques such as the testing of</p><p>physical models with a heliodon.</p><p>Computer modelling of shadows cast by the sun from any position</p><p>is offered by Integrated Environmental Solutions (IES) with its ‘Suncast’</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 54</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>55</p><p>program. This is a user-friendly program which should be well within</p><p>normal undergraduate competence (www.ies4d.com).</p><p>The spacing between buildings is important if overshading is to be</p><p>avoided during winter months when the benefit of solar heat gain</p><p>reaches its peak. On sloping sites there is a critical relationship between</p><p>the angle of slope and the level of overshading. For example, if over-</p><p>shading is to be avoided at a latitude of 50�N, rows of houses on a 10�</p><p>north-facing slope must be more than twice as far apart than on</p><p>10� south-facing slope.</p><p>Trees can obviously obstruct sunlight. However, if they are decidu-</p><p>ous, they perform the dual function of permitting solar penetration</p><p>during the winter whilst providing a degree of shading in the summer.</p><p>Again spacing between trees and buildings is critical.</p><p>Passive solar design can be divided into three broad categories:</p><p>● direct gain;</p><p>● indirect gain;</p><p>● attached sunspace or conservatory.</p><p>Each of the three categories relies in a different way on the ‘greenhouse</p><p>effect’ as a means of absorbing and retaining heat. The greenhouse effect</p><p>in buildings is that process which is mimicked by global environmental</p><p>warming. In buildings, the incident solar radiation is transmitted by</p><p>facade glazing to the interior where it is absorbed by the internal</p><p>surfaces causing warming. However, re-emission of heat back through</p><p>Figure 5.1</p><p>Stereographic sun chart for 21 March</p><p>AIAC-Ch05.qxd</p><p>03/25/2005 17:12 Page 55</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>56</p><p>the glazing is blocked by the fact that the radiation is of a much longer</p><p>wavelength than the incoming radiation. This is because the re-emission</p><p>is from surfaces at a much lower temperature and the glazing reflects</p><p>back such radiation to the interior.</p><p>Direct gain</p><p>Direct gain is the design technique in which one attempts to concen-</p><p>trate the majority of the building’s glazing on the sun-facing facade.</p><p>Solar radiation is admitted directly into the space concerned. Two</p><p>examples 30 years apart are the author’s house in Sheffield, designed in</p><p>1967 (Figure 5.2) and the Hockerton Project of 1998 by Robert and</p><p>Brenda Vale (Figure 5.3). The main design characteristics are:</p><p>● Apertures through which sunlight is admitted should be on the solar</p><p>side of the building, within about �30� of south for the northern</p><p>hemisphere.</p><p>● Windows facing west may pose a summer overheating risk.</p><p>● Windows should be at least double glazed with low emissivity glass</p><p>(Low E) as now required by the UK Building Regulations.</p><p>● The main occupied living spaces should be located on the solar</p><p>side of the building.</p><p>● The floor should be of a high thermal mass to absorb the heat and</p><p>provide thermal inertia, which reduces temperature fluctuations</p><p>inside the building.</p><p>● As regards the benefits of thermal mass, for the normal daily cycle</p><p>of heat absorption and emission, it is only about the first 100 mm of</p><p>thickness which is involved in the storage process. Thickness</p><p>greater than this provides marginal improvements in performance</p><p>but can be useful in some longer-term storage options.</p><p>● In the case of solid floors, insulation should be beneath the slab.</p><p>● A vapour barrier should always be on the warm side of any insulation.</p><p>● Thick carpets should be avoided over the main sunlit and heat-</p><p>absorbing portion of the floor if it serves as a thermal store.</p><p>However, with suspended timber floors a carpet is an advantage in</p><p>excluding draughts from a ventilated underfloor zone.</p><p>During the day and into the evening the warmed floor should slowly</p><p>release its heat, and the time period over which it happens makes it a</p><p>very suitable match to domestic circumstances when the main demand</p><p>for heat is in the early evening.</p><p>As far as the glazing is concerned, the following features are</p><p>recommended:</p><p>● Use of external shutters and/or internal insulating panels might be</p><p>considered to reduce night-time heat loss.</p><p>● To reduce the potential of overheating in the summer, shading may</p><p>be provided by designing deep eaves or external louvres. Internal</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 56</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>57</p><p>blinds are the most common technique but have the disadvantage</p><p>of absorbing radiant heat thus adding to the internal temperature.</p><p>● Heat reflecting or absorbing glass may be used to limit overheating.</p><p>The downside is that it also reduces heat gain at times of the year</p><p>when it is beneficial.</p><p>● Light shelves can help reduce summer overheating whilst improving</p><p>daylight distribution (see Chapter 14).</p><p>Figure 5.2</p><p>Passive solar house, Sheffield 1960s</p><p>Figure 5.3</p><p>Passive solar houses, Hockerton</p><p>Self-Sufficient Housing Project 1998</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 57</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>58</p><p>Direct gain is also possible through the glazing located between the</p><p>building interior and attached sunspace or conservatory; it also takes</p><p>place through upper level windows of clerestory designs. In each of</p><p>these cases some consideration is required concerning the nature and</p><p>position of the absorbing surfaces.</p><p>In the UK climate and latitude as a general rule of thumb room</p><p>depth should not be more than two and a half times the window head</p><p>height and the glazing area should be between about 25 and 35 per cent</p><p>of the floor area.</p><p>Indirect gain</p><p>In this form of design a heat absorbing element is inserted between the</p><p>incident solar radiation and the space to be heated; thus the</p><p>heat is transferred in an indirect way. This often consists of a wall placed</p><p>behind glazing facing towards the sun, and this thermal storage wall</p><p>controls the flow of heat into the building. The main elements</p><p>Figure 5.4</p><p>Hockerton individual house unit solar</p><p>space</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 58</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>59</p><p>contributing to the functioning of the design are:</p><p>● High thermal mass element positioned between sun and internal</p><p>spaces, the heat absorbed slowly conducts across the wall and is</p><p>liberated to the interior some time later.</p><p>● Materials and thickness of the wall are chosen to modify the heat</p><p>flow. In homes the flow can be delayed so that it arrives in the evening</p><p>matched to occupancy periods. Typical thicknesses of the thermal</p><p>wall are 20–30 cm.</p><p>● Glazing on the outer side of the thermal wall is used to provide</p><p>some insulation against heat loss and help retain the solar gain by</p><p>making use of the greenhouse effect.</p><p>● The area of the thermal storage wall element should be about</p><p>15–20 per cent of the floor area of the space into which it emits heat.</p><p>● In order to derive more immediate heat benefit, air can be circu-</p><p>lated from the building through the air gap between wall and</p><p>glazing and back into the room. In this modified form this element</p><p>is usually referred to as a Trombe wall. Heat reflecting blinds should</p><p>be inserted between the glazing and the thermal wall to limit heat</p><p>build-up in summer (Figures 5.5 and 5.6).</p><p>In countries which receive inconsistent levels of solar radiation</p><p>throughout the day because of climatic factors (such as in the UK), the</p><p>option to circulate air is likely to be of greater benefit than awaiting its</p><p>arrival after passage through the thermal storage wall.</p><p>At times of excess heat gain the system can provide alternative</p><p>benefits with the air circulation vented directly to the exterior carrying</p><p>Figure 5.5</p><p>Indirect solar – Trombe wall</p><p>Flap to control reverse</p><p>flow at night</p><p>Thermal storage wall</p><p>Opening to permit air flow</p><p>Figure 5.6</p><p>Freiburg Solar House showing Trombe</p><p>walls with blinds in operation. Note</p><p>the hydrogen storage tank on the right</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 59</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>60</p><p>Figure 5.7</p><p>Attached sunspace</p><p>Blinds/</p><p>insulation</p><p>Air movement between</p><p>sunspace and building</p><p>Direct gainIndirect gain</p><p>away its heat, at the same time drawing in outside air to the building</p><p>from cooler external spaces.</p><p>Indirect gain options are often viewed as being the least aestheti-</p><p>cally pleasing of the passive solar options, partly because of the restric-</p><p>tions on position and view out from remaining windows, and partly as</p><p>a result of the implied dark surface finishes of the absorbing surfaces.</p><p>As a result, this category of the three prime solar design technologies is</p><p>not as widely used as its efficiency and effectiveness would suggest.</p><p>Attached sunspace/conservatory</p><p>This has become a popular feature in both new housing and as an addi-</p><p>tion to existing homes. It can function as an extension of living space, a</p><p>solar heat store, a preheater for ventilation air or simply an adjunct</p><p>greenhouse for plants (Figure 5.7). On balance it is considered that</p><p>conservatories are a net contributor to global warming since they are</p><p>often heated. Ideally the sunspace should be capable of being isolated</p><p>from the main building to reduce heat loss in winter and excessive gain</p><p>in summer. The area of glazing in the sunspace should be 20–30 per cent</p><p>of the area of the room to which it is attached. The most adventurous</p><p>sunspace so far encountered is in the Hockerton housing development</p><p>which will feature later (Chapter 8 and see Figure 5.4).</p><p>Ideally the summer heat gain should be used to charge a seasonal</p><p>thermal storage element to provide background warmth in winter.</p><p>At the very least, air flow paths between the conservatory and the main</p><p>building should be carefully controlled.</p><p>Active solar thermal systems</p><p>A distinction must be drawn between passive means of utilising the ther-</p><p>mal heat of the sun,</p><p>alike within the construction industry</p><p>need to be aware of the importance of their role in creating architecture</p><p>which not only raises the quality of life but also ensures that such quality</p><p>is sustainable.</p><p>Lord Rogers of Riverside</p><p>xi</p><p>AIAC-FM 03/29/2005 17:25 Page xi</p><p>Acknowledgements</p><p>I should like to express my thanks to the following practices for their</p><p>help in providing illustrations and commenting on the text: Bennetts</p><p>Associates, Bill Dunster Architects, Foster and Partners, Michael</p><p>Hopkins and Partners, Jestico � Whiles, RMJM, Richard Rogers</p><p>Partnership, Alan Short Architects, Fielden Clegg Bradley, Studio E</p><p>Architects, David Hammond Architects, Grimshaw Architects Ove Arup</p><p>and Partners.</p><p>I am also indebted to Dr Randall Thomas for his valuable advice on</p><p>the text, Dr William Bordass for providing information from his ‘Probe’</p><p>studies, Dr Adrian Pitts of Sheffield University, Nick White of the</p><p>Hockerton Housing Project, Ray Morgan of Woking Borough Council</p><p>and finally Rick Wilberforce of Pilkington plc for keeping me up to date</p><p>with developments in glazing.</p><p>xii</p><p>AIAC-FM 03/29/2005 17:25 Page xii</p><p>Introduction</p><p>This book calls for changes in the way we build. For change to be widely</p><p>accepted there have to be convincing reasons why long-established prac-</p><p>tices should be replaced. The first part of the book seeks to set out those</p><p>reasons by arguing that there is convincing evidence that climate changes</p><p>now under way are primarily due to human activity in releasing carbon</p><p>dioxide (CO2) into the atmosphere. Buildings are particularly implicated in</p><p>this process, being presently responsible for about 47 per cent of carbon</p><p>dioxide emissions across the 25 nations of the European Union. This</p><p>being the case it is appropriate that the design and construction of build-</p><p>ings should be a prime factor in the drive to mitigate the effects of climate</p><p>change.</p><p>One of the guiding principles in the production of buildings is that</p><p>of integrated design, meaning that there is a constructive dialogue</p><p>between architects and services engineers at the inception of a project.</p><p>The book is designed to promote a creative partnership between the</p><p>professions to produce buildings which achieve optimum conditions</p><p>for their inhabitants whilst making minimum demands on fossil-based</p><p>energy.</p><p>A difficulty encountered by many architects is that of persuading</p><p>clients of the importance of buildings in the overall strategy to reduce</p><p>carbon dioxide emissions. The first chapters of the book explain the</p><p>mechanism of the greenhouse effect and then summarise the present</p><p>situation vis-à-vis global warming and climate change. This is followed</p><p>by an outline of the international efforts to curb the rise in greenhouse</p><p>gases. The purpose is to equip designers with persuasive arguments as</p><p>to why this approach to architecture is a vital element in the battle to</p><p>avoid the worst excesses of climate change.</p><p>At the same time it is important to appreciate that there are</p><p>absolute limits to the availability of fossil fuels, a problem that will</p><p>gather momentum as developing countries like China and India main-</p><p>tain their dramatic rates of economic growth.</p><p>China may well serve to give a foretaste of the future. By 2005</p><p>it had reached 1.3 billion population; at this rate by 2030 it will reach</p><p>1.6 billion. The crucial factor is that the great bulk of this population is</p><p>concentrated in the great valleys of the Yangtze and Yellow Rivers and</p><p>xiii</p><p>AIAC-FM 03/29/2005 17:25 Page xiii</p><p>their tributaries, an area about the size of the USA. China is on the</p><p>verge of consuming more than it can produce. By 2025 it will be import-</p><p>ing 175 million tonnes of grain per year and by 2030 200 million tonnes,</p><p>which equals present total world exports (US National Intelligence</p><p>Council). Its appetite for steel and building materials is voracious and</p><p>already pushing up world prices.</p><p>A supply of energy sufficient to match the rate of economic growth</p><p>is China’s prime concern. Between January and April 2004 demand for</p><p>energy rose 16 per cent. In 2003 it spent £13 billion on hydroelectric,</p><p>coal fired and nuclear power plants – a rate of expansion that equals</p><p>Britain’s entire electrical output every two years. According to a</p><p>spokesman for the Academy of Engineering of China, the country will</p><p>need an additional supply equivalent to four more Three Gorges hydro-</p><p>electric dams, 26 Yanzhou coal mines, six new oil fields, eight gas</p><p>pipelines, 20 nuclear power stations and 400 thermal power generators.</p><p>Carbon has been slowly locked in the earth over millions of years</p><p>creating massive fossil reserves. The problem is that these reserves of</p><p>carbon are being released as carbon dioxide into the atmosphere at a</p><p>rate unprecedented in the paleoclimatic record. The pre-industrial</p><p>atmospheric concentration of CO2 was around 270 parts per million by</p><p>volume (ppmv). Today it is approximately 380 ppmv and is rising by</p><p>about 20 ppmv per decade. The aim of the scientific community is that</p><p>we should stabilise atmospheric CO2 at under 500 ppmv by 2050</p><p>acknowledging that this total will nevertheless cause severe climate</p><p>damage. However, if the present trend is maintained we could expect</p><p>concentrations exceeding 800 ppmv by the second half of the century.</p><p>Given the absence of a political consensus following the refusal of the</p><p>US to ratify the Kyoto Protocol, the 800 plus figure looks ever more</p><p>likely unless there are widespread and radical strategies that bypass</p><p>political agreements, and this is where architects and engineers have a</p><p>crucial part to play.</p><p>The Earth receives annually energy from the sun equivalent to</p><p>178 000 terawatt years which is around 15 000 times the present world-</p><p>wide energy consumption. Of that, 30 per cent is reflected back into</p><p>space, 50 per cent is absorbed and re-radiated, and 20 per cent powers</p><p>the hydrological cycle. Only 0.6 per cent powers photosynthesis from</p><p>which all life derives and which created our reserves of fossil fuel. The</p><p>security of the planet rests on our ability and willingness to use this free</p><p>energy without creating unsavoury side effects, like the range of pollu-</p><p>tants released by the burning of fossil fuels. The greatest potential for</p><p>realising this change lies in the sphere of buildings, which, in the UK,</p><p>account for almost 50 per cent of all CO2 emissions. The technology</p><p>exists to cut this by half in both new and existing buildings. Already</p><p>demonstration projects have proved that reductions can reach 80–90</p><p>per cent against the current norm. The opportunity rests with architects</p><p>and services engineers to bring about this step-change in the way</p><p>buildings are designed. In the 1960s–1970s buildings were symbols</p><p>INTRODUCTION</p><p>xiv</p><p>AIAC-FM 03/29/2005 17:25 Page xiv</p><p>of human hubris, challenging nature at every step. The turn of the</p><p>millennium saw a new attitude gathering momentum in a synergy</p><p>between human activity and the forces of nature. Nowhere can this be</p><p>better demonstrated than in the design of buildings.</p><p>In 2000 the Royal Commission on Environmental Pollution pro-</p><p>duced a report on Energy – The Changing Climate. It concludes: ‘To</p><p>limit the damage beyond that which is already in train, large reductions</p><p>of global emissions will be necessary during this century and the next.</p><p>Strong and effective action has to start immediately.’</p><p>Peter F. Smith</p><p>January 2005</p><p>INTRODUCTION</p><p>xv</p><p>AIAC-FM 03/29/2005 17:25 Page xv</p><p>AIAC-FM 03/29/2005 17:25 Page xvi</p><p>Chapter</p><p>One</p><p>1</p><p>Climate change – nature or</p><p>human nature?</p><p>The key question is this: climate change is now widely accepted as</p><p>being a reality, so, is it a natural process in a sequence of climate</p><p>changes that have occurred over the paleoclimatic record or is it being</p><p>driven by humans? If we hold to the former view then all we can hope</p><p>for is to adapt as best we can to the climate disruption. On the other</p><p>hand, if we accept that it is largely human induced, then it follows that</p><p>we ought to be able to do something about it.</p><p>There is widespread agreement among climate scientists worldwide</p><p>discussed earlier, and those of a more ‘active’ nature.</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 60</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>61</p><p>Active systems take solar gain a step further than passive solar. They</p><p>convert direct solar radiation into another form of energy. Solar collectors</p><p>preheat water using a closed circuit calorifier. The emergence of</p><p>Legionella has highlighted the need to store hot water at a temperature</p><p>above 60�C which means that for most of the year in temperate climes</p><p>active solar heating must be supplemented by some form of heating.</p><p>Active systems are able to deliver high quality energy. However,</p><p>a penalty is incurred since energy is required to control and operate the</p><p>system known as the ‘parasitic energy requirement’. A further distinc-</p><p>tion is the difference between systems using the thermal heat of the</p><p>sun, and systems, such as photovoltaic cells, which convert solar energy</p><p>directly into electrical power.</p><p>For solar energy to realise its full potential it needs to be installed</p><p>on a district basis and coupled with seasonal storage. One of the</p><p>largest projects is at Friedrichshafen (Figure 5.8). The heat from 5600 m2</p><p>heating central heat</p><p>transfer</p><p>substation</p><p>heat</p><p>transfer</p><p>substationgas</p><p>burner</p><p>hot</p><p>tap</p><p>water</p><p>hot</p><p>tap</p><p>water</p><p>CCCC</p><p>fresh</p><p>water</p><p>fresh</p><p>water</p><p>solar network</p><p>district heating network</p><p>hot water heat storage (seasonal storage)</p><p>Schematic drawing of the CSHPSS system in Friedrichshafen, Germany</p><p>so</p><p>lar c</p><p>olle</p><p>cto</p><p>rs</p><p>so</p><p>lar c</p><p>olle</p><p>cto</p><p>rs</p><p>Figure 5.8</p><p>Diagram of CSHPSS system, Friedrichshafen (courtesy of Renewable Energy World (REW))</p><p>AIAC-Ch05.qxd 03/25/2005 17:12 Page 61</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>62</p><p>Figure 5.9</p><p>Seasonal storage tank under</p><p>construction, Friedrichshafen (courtesy</p><p>of REW)</p><p>of solar collectors on the roofs of eight housing blocks containing 570</p><p>apartments is transported to a central heating unit or substation. It is</p><p>then distributed to the apartments as required. The heated living area</p><p>amounts to 39 500 m2.</p><p>Surplus summer heat is directed to the seasonal heat store which,</p><p>in this case, is of the hot water variety capable of storing 12 000 m3. The</p><p>scale of this storage facility is indicated by Figure 5.9.</p><p>The heat delivery of the system amounts to 1915 MWh/year and</p><p>the solar fraction is 47 per cent. The month by month ratio between</p><p>solar and fossil-based energy indicates that from April to November</p><p>inclusive, solar energy accounts for almost total demand, being princi-</p><p>pally domestic hot water.</p><p>In places with high average temperatures and generous sunlight,</p><p>active solar has considerable potential not just for heating water but</p><p>also for electricity generation. This has particular relevance to less and</p><p>least developed countries.</p><p>Types of solar thermal collector</p><p>The flat plate collector</p><p>These units are, as the name indicates, flat plates tilted to receive</p><p>maximum solar radiation. Behind the plate are pipes which carry the</p><p>heat extraction medium. There are two types of heat absorbing</p><p>medium, air and water. Water containing an anti-freeze solution is the</p><p>most common and is circulated behind an absorber plate to extract and</p><p>transfer its heat. In the UK they are usually limited to providing domes-</p><p>tic hot water, mainly in the summer months. To exploit their efficiency to</p><p>AIAC-Ch05.qxd 03/25/2005 17:13 Page 62</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>63</p><p>the full there should be a heat storage facility which accepts excess</p><p>heat during the summer to top up heating needs the rest of the year.</p><p>However, the size of both the collectors and storage tanks makes this</p><p>an uneconomic proposition in most cases.</p><p>There are four main components to the design:</p><p>● transparent cover plate;</p><p>● heat absorber plate;</p><p>● a pipe circuit to absorb and transport the heat;</p><p>● insulation behind the plate and pipes (Figures 5.10 and 5.12).</p><p>A more sophisticated version was devised for the Freiburg Solar</p><p>House. The collector is placed within a semi-circular reflector. The</p><p>reflected radiation means that the collector receives heat on both</p><p>sides, nearly doubling its efficiency. Coupled with insulated water</p><p>storage this system was able to supply all the domestic hot water for</p><p>the whole year (Figure 5.11).</p><p>Evacuated tube collectors</p><p>The most recent form of collector is the evacuated tube or vacuum tube</p><p>system. It works by exploiting a vacuum around the collector which</p><p>reduces heat loss from the system, making it especially suitable for</p><p>more temperate climes. These units heat water from 60 to 80�C which is</p><p>Figure 5.10</p><p>Flat plate collector</p><p>Transparent cover plate</p><p>Absorber plate</p><p>Insulator</p><p>Flow passages</p><p>Figure 5.11</p><p>Double-sided solar collector, Freiburg</p><p>Solar House</p><p>1. Absorber</p><p>2. Air gap</p><p>3. Transparent insulation</p><p>4. Low iron containing glass</p><p>5. Reflector</p><p>AIAC-Ch05.qxd 03/25/2005 17:13 Page 63</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>64</p><p>Figure 5.12</p><p>Flat bed solar thermal collectors,</p><p>Osney Island, Oxford (courtesy of</p><p>David Hammond, Architect)</p><p>sufficient for providing domestic hot water. They can continue to oper-</p><p>ate under cloudy conditions and should be linked to an insulated</p><p>storage facility for continuity of supply. However, the installation cost is</p><p>significantly higher than for flat bed collectors. (For more informa-</p><p>tion see Smith, P.F. (2002) Sustainability at the Cutting Edge, Ch. 2,</p><p>Architectural Press.)</p><p>Windows and glazing</p><p>In recent years there has been rapid development in the technology of</p><p>the building envelope, especially in the sphere of glass. Glazing systems</p><p>are now possible which react to environmental conditions such as light</p><p>and heat, yet these are merely a foretaste of things to come. Also there</p><p>have been considerable advances in the thermal efficiency of glazing,</p><p>with U-values now commercially better than 1.0 W/m2K. Table 5.1 shows</p><p>the heat transfer characteristics of seven glazing systems.</p><p>Table 5.2 illustrates the impact of solar gain according to orienta-</p><p>tion by giving the net U-values.</p><p>Windows have many benefits, aside from the obvious. Nevertheless,</p><p>they are the main weak thermal link when incorrectly specified.</p><p>Discomfort arises in summer, not just from the rise in air temperature</p><p>due to heat gains, but also due to the rise in radiant temperature from</p><p>the glass surface itself. Radiant effects are further increased if the</p><p>AIAC-Ch05.qxd 03/25/2005 17:13 Page 64</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>65</p><p>occupant experiences unshaded sunlight. In winter, cold window sur-</p><p>faces cool the adjacent internal air, which then falls under the buoyancy</p><p>effect leading to a cold downdraught. This would also be accompanied</p><p>by a cool radiant temperature. Along with the change in temperature,</p><p>there may well be an asymmetric temperature field leading to greater</p><p>discomfort.</p><p>As pressure has increased to improve the thermal efficiency of</p><p>buildings this has forced the pace of developments in glass technology.</p><p>The following are some examples.</p><p>Heat reflecting and heat absorbing glazing</p><p>These products are usually considered for application in situations</p><p>where overheating poses a risk. Visible light and solar heat gain are</p><p>both parts of the electromagnetic spectrum of energy emitted by the</p><p>sun. The interaction of glazing with light and solar heat has three</p><p>components: reflection, absorption and transmission.</p><p>Modifications in the proportions of reflected, absorbed and trans-</p><p>mitted radiation could be engineered by changing the glazing system</p><p>properties. There are several ways of achieving this:</p><p>● using ‘body tinted’ glass, which increases absorption;</p><p>● using reflective coatings, which increase the reflected component</p><p>and, usually, the absorbed component;</p><p>● using combinations of body tinted and reflective coatings.</p><p>Table 5.1</p><p>Comparison of typical heat transfer</p><p>through different glazing options</p><p>Glazing U-value (W/m2K)</p><p>Single glazing 5.6</p><p>Double glazing 3.0</p><p>Triple glazing 2.4</p><p>Double with Low E 2.4</p><p>Double with Low E and Argon 2.2</p><p>Triple with 2 Low E and 2 Argon 1.0</p><p>Double with Aerogel 0.5–1.0</p><p>Glazing U-value ( W/m2K) with solar gain</p><p>South East/west</p><p>North</p><p>Single glazing 2.8–3.7 3.7–4.6 4.6–5.6</p><p>Double glazing 0.7–1.4 1.4–2.2 2.2–3.0</p><p>Triple glazing 0.0–0.6 0.6–1.1 1.1–2.4</p><p>Double with Low E 0.1–0.8 0.8–1.2 1.2–2.4</p><p>Triple with Low E �0.5–0.3 0.3–0.9 0.9–1.6</p><p>Table 5.2</p><p>Effective net U-value taking account of</p><p>solar heat gain</p><p>AIAC-Ch05.qxd 03/25/2005 17:13 Page 65</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>66</p><p>It must be remembered that a reduction in solar heat gain can only be</p><p>achieved at the cost of reducing daylight transmission, though some</p><p>tinting and reflective products are more selective than others. The</p><p>reflected component can be increased by changing the angle of</p><p>incidence – the more acute the angle, the greater the reflection.</p><p>Body tinted glass is normally available in a range of colours including</p><p>grey, green, bronze and blue. The tinting is produced by the addition of</p><p>small amounts of metal oxides during production, and it is present</p><p>throughout the thickness of the glass. The effect is to increase the</p><p>absorption of the radiation within the glazing, reducing the directly</p><p>transmitted component. However, the heat absorbed must be dissi-</p><p>pated as the glass temperature increases. The warmth of the glass</p><p>transmits heat inwards as well as outwards. Because of this the body</p><p>tinted layer would normally be installed as the outer pane of a multi-</p><p>pane unit. Though body tinted glass has an effect on heat transmission</p><p>it also has aesthetic implications.</p><p>For improved solar heat gain attenuation, reflective coated glass</p><p>has a better performance. The coating is applied to the surface of the</p><p>glass which must be installed on the side facing in towards the cavity of</p><p>a sealed unit, or by applying a second laminating layer.</p><p>Reflective coatings are available in a wide range of colours and with</p><p>a wide range of performance specifications. It is easier to specify and</p><p>produce a glass with specific properties for a specific application than</p><p>with body tinted varieties. In hot climates, glazing is specified to reduce</p><p>heat gain, both by direct solar transmission, which can be as low as 10</p><p>per cent in some cases, and by conduction. To achieve this second aim,</p><p>a double glazed unit with a reflective outer layer is combined with a low</p><p>emissivity coated inner layer to reflect outwards the heat which is trans-</p><p>mitted. Avoidance of glare and the provision of some natural light and</p><p>view, are also considerations. In temperate climates a balance must be</p><p>struck between control of summer heat gain and the benefits of winter</p><p>sun, plus the fact that higher levels of natural daylight are required. No</p><p>two situations are quite the same and it is important to consider the full</p><p>range of options before choosing a particular product or glazing system.</p><p>Photochromic, thermochromic and</p><p>electrochromic glass</p><p>Each of these terms describes a variety of glazing in which the trans-</p><p>mission properties are variable. Extensive opportunities exist for the</p><p>development of some of these technologies to allow dynamic control</p><p>of light and heat gain to match building and occupant requirements.</p><p>Photochromic devices change transmission in response to prevailing</p><p>radiation levels. Small examples have been in everyday use for some</p><p>years in the form of sunglasses and spectacles. These react automatically</p><p>to light levels. There are considerable technical problems to scaling up</p><p>photochromic glass to normal window size.</p><p>AIAC-Ch05.qxd 03/25/2005 17:13 Page 66</p><p>LOW ENERGY TECHNIQUES FOR HOUSING</p><p>67</p><p>Thermochromic glass has changing optical properties in response</p><p>to temperature variations. It has a laminated structure incorporating a</p><p>chemical which turns opaque at around 30�C, reducing insolation by</p><p>about 70 per cent. For this reason an ideal application is as external</p><p>solar shading. As it reacts to heat it may not be so suitable for windows</p><p>since it could react to the internal temperature and again cannot be</p><p>independently controlled.</p><p>The most refined and controllable of the three options is elec-</p><p>trochromic glass, the properties of which can be changed by the</p><p>application of a small electrical current. Their construction consists of</p><p>complex multi-layered transparent coatings. The electrical signal</p><p>reduces the transmission capacity of the electrochromic layer between</p><p>two sheets of glass affecting not only daylight but also solar heat.</p><p>The latest version from Pilkington is EControl glass which can, at</p><p>the flick of a switch, cut out over 80 per cent of solar radiation. It can</p><p>also achieve an airborne sound insulation level of 42 dB using thicker</p><p>internal glass and a special sound insulating gas between the panes.</p><p>Pilkington is also developing a solid state electrochromic glass, in other</p><p>words, without any applied coatings.</p><p>Capital cost savings in terms of reduced cooling requirements and</p><p>the exclusion of blinds plus revenue savings in respect of lower energy</p><p>costs make electrochromic glass an attractive option, especially since</p><p>it can be controlled by the occupants – a major factor in workplace</p><p>satisfaction.</p><p>Pilkington has recently marketed a self-cleaning or ‘hydrophilic’</p><p>glass known commercially as ‘Pilkington Activ’. Rainwater forms an</p><p>overall film on the glass rather than collecting in drops that deposit dirt</p><p>which remains after drying. This should offer significant revenue cost</p><p>savings in maintenance, especially for commercial buildings.</p><p>Romag, a company specialising in laminated glass, has joined with</p><p>BP Solar to produce a composite glass which incorporates PV cells. It</p><p>will be marketed as PowerGlaz and should be available towards the end</p><p>of 2004. It will be available in a range of sizes up to 3.3 � 2.2 metres.</p><p>AIAC-Ch05.qxd 03/25/2005 17:13 Page 67</p><p>68</p><p>Chapter</p><p>Six</p><p>Insulation</p><p>Warmth is a valuable commodity and it will seek every possible means</p><p>of escape from walls, roofs, windows and floors. Most UK buildings</p><p>make escape easy.</p><p>Heat flow through building components can be modified by the</p><p>choice of materials. The main heat transfer process for solid, opaque</p><p>building elements is by conduction. Thermal insulation, which provides</p><p>a restriction to heat flow, is used to reduce the magnitude of heat flow</p><p>in a ‘resistive’ manner. Since air provides good resistance to heat flow,</p><p>many insulation products are based upon materials that have numerous</p><p>layers or pockets of air trapped within them. Such materials are thus low</p><p>density and lightweight, and, in most cases, not capable of giving struc-</p><p>tural strength. Generally, the higher the density, the greater the heat</p><p>flow. Since structural components are often, of necessity, rather high in</p><p>density, they are unable to provide the same level of resistive insulation.</p><p>Warmth is a valuable commodity and it will seek every possible means</p><p>to escape from a building. Walls, roofs, floors, chimneys, windows are</p><p>all escape routes.</p><p>It may be necessary to provide additional layers of insulation around</p><p>them to prevent such elements acting as weak links or ‘cold bridges’ in</p><p>the thermal design.</p><p>Increased levels of insulation are a cost-effective way of reducing</p><p>heating energy consumption. In several domestic and other small</p><p>buildings, it has already been demonstrated that the additional costs</p><p>of insulation can be offset against a much reduced cost for the heat-</p><p>ing system involving a whole building radiator and central boiler</p><p>option.</p><p>When specifying insulation materials it is important avoid those</p><p>which are harmful to the environment such as materials involving chlo-</p><p>rofluorocarbons (CFCs) in the production process and to select materi-</p><p>als with zero ozone depletion potential (ZODP). Insulation materials fall</p><p>into three main categories:</p><p>● Inorganic/mineral – these include products based on silicon and</p><p>calcium (glass and rock) and are usually evident in fibre boards,</p><p>e.g. glass fibre and ‘Rockwool’.</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 68</p><p>INSULATION</p><p>69</p><p>● Synthetic organic – materials derived from organic feedstocks based</p><p>on polymers.</p><p>● Natural organic – vegetation-based materials like hemp and lamb’s</p><p>wool which must be treated to avoid rot or vermin infestation.</p><p>For fibrous materials such as glass and mineral fibres there is a theoreti-</p><p>cal risk of cancer and non-malignant diseases like bronchitis. This is a</p><p>matter that is still under review (Thomas, R. (ed.) (1996) Environmental</p><p>Design, E & FN Spon).</p><p>The range of insulation options</p><p>There are numerous alternatives when it comes to choosing insulation</p><p>materials. They differ in thermal efficiency and in offering certain impor-</p><p>tant properties like resistance to fire and avoidance of ozone depleting</p><p>chemicals. Some also lose much their insulating efficiency if affected by</p><p>moisture. So, at the outset it is advisable to understand something about</p><p>the most readily available insulants. The thermal efficiency of an insulant</p><p>is denoted by its thermal conductivity, termed lambda value, measured in</p><p>W/mK. The thermal conductivity of a material ‘is the amount of heat</p><p>transfer per unit of thickness for a given temperature difference’</p><p>(Thomas, R. (ed.) (1996) Environmental Design, E & FN Spon, p. 10).</p><p>Technically it is a measure of the rate of heat conduction through 1 cubic</p><p>metre of a material with a 1ºC temperature difference across the two</p><p>opposite faces. The lower the value the more efficient the material.</p><p>Inorganic/mineral-based insulants</p><p>Inorganic/mineral-based insulants come in two forms, fibre or cellular</p><p>structure.</p><p>Fibre</p><p>Rock wool</p><p>Rock wool is produced by melting a base substance at high tempera-</p><p>ture and spinning it into fibres with a binder added to provide rigidity.</p><p>It is vapour and air permeable due to its structure. Moisture can build</p><p>up in the insulant reducing its insulating value. May degrade over time.</p><p>Lambda value 0.033–0.040 W/mK.</p><p>Glass wool</p><p>As for rock wool.</p><p>Health and safety</p><p>There is a health issue with fibrous materials. Some cause skin irritation</p><p>and it is advisable to wear protective gear during installation. Loose fill</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 69</p><p>fibre insulants should not be ventilated to internal habitable spaces.</p><p>There has been the suggestion that fibrous materials constitute a</p><p>cancer risk. However, they are currently listed as ‘not classifiable as to</p><p>carcinogenicity in humans’.</p><p>Cellular</p><p>Cellular glass</p><p>Manufactured from natural materials and over 40 per cent recycled glass.</p><p>It is impervious to water vapour and is waterproof, dimensionally stable,</p><p>non-combustible, vermin-proof and has high compressive strength as well</p><p>as being CFC and HCFC free.</p><p>Lambda value 0.037–0.047 depending on particular application. Typical</p><p>proprietary brand: Foamglas by Pittsburgh Corning (UK) Ltd.</p><p>Vermiculite</p><p>Vermiculite is the name given to a group of geological materials that</p><p>resemble mica. When subject to high temperature the flakes of</p><p>vermiculite expand due to their water content to many times their origi-</p><p>nal size to become ‘exfoliated vermiculite’. It has a high insulation value,</p><p>is resistant to decay, odourless, and non-irritant.</p><p>Organic/synthetic insulants</p><p>Organic/synthetic insulants are confined to cellular structure:</p><p>EPS (expanded polystyrene)</p><p>Rigid, flame retardant cellular, non-toxic, vapour resistant plastic insulation,</p><p>CFC and HCFC free.</p><p>Lambda value 0.032–0.040 W/mK.</p><p>XPS (extruded polystyrene)</p><p>Closed cell insulant water and vapour tight, free from CFCs and HCFCs.</p><p>Lambda value 0.027–0.036 W/mK.</p><p>PIR (polyisocyanurate)</p><p>Cellular plastic foam, vapour tight, available CFC and HCFC free.</p><p>Lambda value 0.025–0.028 W/mK.</p><p>Phenolic</p><p>Rigid cellular foam very low lambda value, vapour tight, good fire resist-</p><p>ance, available CFC and HCFC free.</p><p>Lambda value 0.018–0.019 W/mK.</p><p>In general, cellular materials do not pose a health risk and there are</p><p>no special installation requirements.</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>70</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 70</p><p>Natural/organic insulants</p><p>Fibre structure</p><p>Cellulose Mainly manufactured from recycled newspapers. Manufac-</p><p>tured into fibres, batts or boards. Treated with fire retardant and</p><p>pesticides.</p><p>Lambda value 0.038–0.040 W/mK.</p><p>Sheep’s wool Must be treated with a boron and a fire retardant.</p><p>Disposal may have to be at specified sites.</p><p>Lambda value 0.040 W/mK.</p><p>Flax Treated with polyester and boron.</p><p>Lambda value 0.037 W/mK.</p><p>Straw Heat treated and compressed into fibre boards. Treated with fire</p><p>retardant and pesticide. It can be used as a wall material with a high ther-</p><p>mal efficiency. In its present day form it should be much more reliable</p><p>than the strawboard of the 1960s which had a tendency to germinate.</p><p>Lambda value 0.037 W/mK.</p><p>Hemp Under development as a compressed insulation board.</p><p>A highly eco-friendly material, grows without needing pesticides and</p><p>produces no toxins. Initial tests have used hemp as a building material</p><p>mixed with lime and placed like concrete. Test houses have proved as</p><p>thermally efficient as identical well-insulated brick built houses built</p><p>alongside the hemp examples.</p><p>Main points</p><p>Insulation materials should be free from HFCs and HCFCs:</p><p>● The choice of insulation material is governed primarily by two</p><p>factors: thermal conductivity and location in the home.</p><p>● The ecological preference is for materials derived from organic or</p><p>recycled sources and which do not use high levels of energy during</p><p>production. However, there are certain overriding factors which will</p><p>be described below.</p><p>Embodied energy, that is, energy involved in the extraction and</p><p>manufacturing process, is also a factor to consider. Insulation materials</p><p>derived from mineral fibres tend to be among the lowest in embodied</p><p>energy and also CO2 emissions. However, overall the use of insulation</p><p>saves many times the embodied energy of even the worst cases, for</p><p>example 200 times for expanded polystyrene and 1000 times for glass</p><p>fibre.</p><p>INSULATION</p><p>71</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 71</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>72</p><p>Table 6.1 shows the thermal conductivity of the main insulants.</p><p>Finally, there is the factor of internal strength or friability. Rockwool</p><p>products are among the most stable in this respect. Extruded</p><p>polystyrene foams are attractive to house builders because they have</p><p>good water resistance and a stiffness that enables them to be used in</p><p>cavities.</p><p>High and superinsulation</p><p>In recent years attention has been focused towards the use of very thick</p><p>layers of insulation within the building fabric in order to minimise heat</p><p>flow. This technique has become known as superinsulation. The use of</p><p>superinsulation has so far been best demonstrated at the domestic</p><p>scale. This may be partly due to the problems of overheating experi-</p><p>enced in many larger, deeper plan commercial buildings, problems</p><p>which override the benefits of reduced winter heating requirements. In</p><p>the future, however, buildings which exhibit less tendency to overheat</p><p>due to better environmental design may modify the priorities and make</p><p>superinsulation attractive in all circumstances where buildings experi-</p><p>ence cold seasons.</p><p>Superinsulation is associated with several design features:</p><p>● To qualify as superinsulated the building fabric should have U-values</p><p>that are less than 0.2 W/m2K for all major non-transparent elements</p><p>and often below 0.1 W/m2K.</p><p>● Insulation thickness is often constrained by accepted construction</p><p>techniques, for instance by allowable cavity widths in cavity wall</p><p>construction.</p><p>● A broader definition of superinsulation is one which specifies a</p><p>maximum overall building heat loss which permits ‘trade-offs’ within</p><p>certain limits, rather than individual component values, for example</p><p>by an allowance for solar gain.</p><p>Thermal</p><p>conductivity</p><p>(W/mK)</p><p>Expanded polystyrene slab 0.035</p><p>Extruded polystyrene 0.030</p><p>Glass fibre quilt 0.040</p><p>Glass fibre slab 0.035</p><p>Mineral fibre slab 0.035</p><p>Phenolic foam 0.020</p><p>Polyurethane board 0.025</p><p>Cellulose fibre 0.035</p><p>Table 6.1</p><p>Summary of comparative performance</p><p>of insulation materials</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 72</p><p>INSULATION</p><p>73</p><p>● In the case of low-energy housing, the typical thickness of insulation</p><p>material is likely to be of the order of 150 mm in walls and 300 mm</p><p>in roofs (Figure 6.1); superinsulated</p><p>walls may have 200–300 mm</p><p>with 400 mm in the roof (Figure 6.2).</p><p>● Achieving a superinsulation standard also requires a high level of air</p><p>tightness of the building envelope which means that there will need</p><p>to be trickle ventilation or even mechanical ventilation with heat</p><p>recovery to reinforce the ‘stack effect’ in order to provide one to</p><p>two air changes per hour.</p><p>With cavities of 200–300 mm width it is essential to have rigid wall</p><p>ties of either stainless steel or tough rigid plastic.</p><p>The Jaywick Sands development is a social housing project which</p><p>is designed on sustainability principles. Its ‘breathing’ walls consist of</p><p>Figure 6.1</p><p>Section, typical low energy construction</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 73</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>74</p><p>partially prefabricated storey height structural panels (Figure 6.3). They</p><p>are filled with 170 mm Warmcell insulation and clad with 9 mm sheath-</p><p>ing board faced with a breather membrane. The exterior finish is west-</p><p>ern red cedar boards on battens. The floor is a pot and beam precast</p><p>concrete slab with 60 mm rigid insulation on the upper surface. It can</p><p>be argued that the insulation would have been better on the underside</p><p>of the concrete to allow the slab to provide a degree of thermal</p><p>mass (the scheme is described in detail in The Architects Journal,</p><p>23 November 2000).</p><p>Figure 6.2</p><p>Superinsulation in the Autonomous</p><p>House, Southwell (courtesy of Robert</p><p>and Brenda Vale)</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 74</p><p>INSULATION</p><p>75</p><p>Figure 6.3</p><p>Low energy timber panel housing,</p><p>Jaywick Sands, Essex</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 75</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>76</p><p>On mainland Europe solid wall construction is much more common</p><p>than in the UK. An example is the Zero-energy House at Wadenswil,</p><p>Switzerland. The structural wall consists of 150 mm dense concrete</p><p>blocks. These are faced with 180 mm of extruded polystyrene insulation</p><p>protected by external cladding. The walls have a U-value of 0.15 W/m2K.</p><p>The roof has 180 mm of mineral fibre insulation giving it a U-value of</p><p>0.13 W/m2K.</p><p>Timber framed windows are triple glazed with Low-E coatings and</p><p>an argon gas filled cavity achieving a U-value of 1.2 W/m2K. North facing</p><p>windows are quadruple glazed achieving a U-value of 0.85 W/m2K.</p><p>Air tightness is a prime consideration at this level of energy effi-</p><p>ciency. Pressure tested to 50 pascals (Pa) the rate of air change was</p><p>0.4 per hour. Polycarbonate honeycomb collectors absorb solar radia-</p><p>tion to heat domestic water to 25�C even on cloudy days. Space heating</p><p>is also supplied by solar collectors and delivered in pipes embedded in</p><p>the concrete floors. This is supplemented by a heat storage facility and</p><p>backup liquid petroleum gas (LPG) heater unit. The annual energy</p><p>consumption is around 14 kWh/m2 excluding solar energy (Figure 6.4).</p><p>3 mm bitumous plastic</p><p>Figure 6.4</p><p>Section of the Wadenswil House</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 76</p><p>INSULATION</p><p>77</p><p>Transparent insulation materials</p><p>Transparent insulation materials (usually abbreviated to TIMs) are a class of</p><p>product which make use of particular materials to enhance the solar heat</p><p>gain whilst simultaneously reducing the heat loss by conduction and radia-</p><p>tion. The technology has similarities to the passive solar thermal mass wall</p><p>designs already described, except the gap between glazed outer skin and</p><p>the surface of the wall which faces into it contains insulation which is trans-</p><p>parent rather than just air. The insulation allows transmission of the incom-</p><p>ing solar radiation but acts as a barrier to conductive and radiative heat</p><p>loss, retaining absorbed heat very effectively. Aerogels are a form of</p><p>translucent insulation material which is located within a glazing sandwich.</p><p>Aerogels</p><p>Aerogels are materials that are mostly air – usually around 99 per cent by</p><p>volume – and can be fabricated from silica, metals even rubber. They are</p><p>extremely light. For example, a cubic metre of silica glass would weigh</p><p>about 2000 kilograms. A silica aerogel block of the same dimensions</p><p>would weigh 20 kilograms. Despite this aerogels are relatively strong.</p><p>They are sometimes called ‘frozen smoke’ due to their translucent</p><p>appearance. In the case of the silica aerogel it consists of tiny dense</p><p>silica particles about 1 nanometre across which link up to form a gel.</p><p>Aerogels are excellent insulators, having about one hundredth the</p><p>thermal conductivity of glass. Double glazing which replaced the gap</p><p>with an aerogel would improve the insulation value by a factor of three</p><p>as against the very best current multiple glazing. It would be possible to</p><p>achieve a 99 per cent vacuum between the panes since they are sup-</p><p>ported by a solid. However, even with a thin aerogel sandwich the</p><p>window would have a slightly frosted appearance.</p><p>The thermal properties of aerogels also make them ideal for</p><p>harvesting solar heat. Flat plate solar panels collect heat then radiate it</p><p>back into space. An aerogel glass sandwich would provide a one-way</p><p>barrier to the re-radiation of heat from the absorbing surface. This</p><p>would have an obvious application in active solar panels and also in</p><p>solar walls. The outer surface of the wall would be coated black to max-</p><p>imise absorption. Faced with a glass aerogel screen the heat would be</p><p>retained and radiated into the interior of the building. A blind behind a</p><p>glazed rain screen would minimise an excessive build-up of heat in</p><p>summer (Figure 6.5). The Freiburg Solar House shows Trombe walls with</p><p>some blinds lowered (Figure 5.6).</p><p>Insulation – the technical risks</p><p>The use of high levels of insulation brings with it some risks. Some</p><p>problems relate to the presence of moisture within the building</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 77</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>78</p><p>construction which, because the temperature gradient has been</p><p>changed by the presence of insulation, condenses into water. This can</p><p>lead to several difficulties such as rotting, rusting or other degradation</p><p>of components, and in addition can pose a safety risk if it comes into</p><p>contact with electrical circuitry. Some insulation materials absorb mois-</p><p>ture, and when wet, their insulating effect is very much reduced. Cavity</p><p>insulation should be treated with a water repellent.</p><p>If substantial variations exist between the insulation levels of</p><p>different parts of the building fabric, this creates weak links, which then</p><p>become the main cold bridges or ‘thermal bridges’. It is on the inner</p><p>surfaces of such cold bridges that condensation will occur. The answer</p><p>is to ensure continuity of insulation. The problem mainly occurs at the</p><p>junction between main structural components, for example:</p><p>● at the junction of roof and wall;</p><p>● or wall and floor;</p><p>● around windows and doors, particularly frames and lintels;</p><p>● around apertures for building services – electrical, water, drainage, etc.;</p><p>● at positions where structural framing elements connect with roofs,</p><p>walls and floors.</p><p>When considering floors, the majority of the heat loss occurs at its</p><p>exposed edges. Particular attention must therefore be paid to ensuring</p><p>adequate and correctly designed insulation details at floor edges.</p><p>Figure 6.5</p><p>Transparent/translucent insulation wall</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 78</p><p>INSULATION</p><p>79</p><p>The use of vapour barriers becomes more important as insulation</p><p>levels rise, since it is the appropriate construction and positioning of</p><p>such layers that reduces condensation risk. It is advisable to carry out a</p><p>technical assessment of the condensation risk if this is suspected of</p><p>being a problem. It is even more important to design components cor-</p><p>rectly and ensure that the construction is carried out according to the</p><p>specification. A large proportion of the reported faults associated with</p><p>condensation are attributable to poor workmanship. As stated earlier,</p><p>as a general principle, vapour barriers should always be on the warm</p><p>side of the insulation, otherwise they will actually cause condensation.</p><p>AIAC-Ch06.qxd 03/25/2005 17:14 Page 79</p><p>80</p><p>Chapter</p><p>Seven</p><p>Domestic energy</p><p>Electricity produced by a stand-alone system within, or linked to, a</p><p>building is called ‘embedded’ energy generation. By far the most con-</p><p>venient form of renewable energy system which can be linked to hous-</p><p>ing is photovoltaic cells. As unit costs fall PV arrays attached to individual</p><p>houses will become increasingly evident. In several countries there are</p><p>substantial state subsidies to kick-start the PV industry so that costs can</p><p>quickly fall due to the economy of scale. One of the pioneer examples</p><p>of a domestic application in the UK is the Autonomous House by Robert</p><p>and Brenda Vale in Southwell, Nottinghamshire (Figure 7.1).</p><p>Photovoltaic systems</p><p>As stated earlier PV cells have no moving parts, create no noise in opera-</p><p>tion, and seem attractive from both aesthetic and scientific perspectives.</p><p>Figure 7.1</p><p>Remote PV array, Autonomous House,</p><p>Southwell, also with an indication of</p><p>the sunspace</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 80</p><p>DOMESTIC ENERGY</p><p>81</p><p>Power output is constrained by the availability of light falling on the cell,</p><p>though significant output is still possible with overcast skies.</p><p>The development of PV cells is gathering pace as indicated by the</p><p>fact that the manufacturing capacity for PVs increased by 56 per cent in</p><p>Europe and 46 per cent in Japan alone between 2001 and 2002. The</p><p>greatest potential growth area is with building integrated PVs within</p><p>facade and roof components. Examples of PV integrated cladding</p><p>include the adaptation of rain screens, roof tiles and windows.</p><p>The advantages of building integrated systems are:</p><p>● clean generation of electricity;</p><p>● generation at its point of use within the urban environment thus</p><p>avoiding infrastructure costs and line losses;</p><p>● no additional land requirements.</p><p>As a result a number of national and international development pro-</p><p>grammes now exist to help exploit the opportunities offered.</p><p>Germany has been one of the frontrunners in promoting the appli-</p><p>cation of PVs to buildings. Its Renewable Energy Law offered significant</p><p>added value to the production of electricity from domestic PV roofs. Its</p><p>initial target of 100 000 PV roofs has been surpassed. This law has recently</p><p>been re-enacted and a further 100 000 PV roofs target has been instigated.</p><p>The principle of photovoltaic cells (PVs)</p><p>PVs are devices which convert light directly into electricity. At present</p><p>most PVs consist of two thin layers of a semi-conducting material, each</p><p>layer having different electrical characteristics. In most common PV cells</p><p>both layers are made from silicon but with different, finely calculated</p><p>amounts of impurities: p-type and n-type. The introduction of impurities</p><p>is known as ‘doping’. As a result of the doping one layer of silicon is neg-</p><p>atively charged (n-type) and has a surplus of electrons. The other layer is</p><p>given a positive charge (p-type) and an electron deficit. These two</p><p>neighbouring regions generate an electrical field. When light falls on a</p><p>PV cell electrons are liberated by the radiative energy from the sun and</p><p>able to migrate from one side to the other. Some of the electrons are</p><p>captured as useful energy and directed to an external circuit (Figure 7.2).</p><p>Cells with different characteristics and efficiencies can be created</p><p>by using different base and doping materials. The output is direct cur-</p><p>rent (DC) which must be changed to alternating current (AC) by means</p><p>of an inverter if it is to be fed to the grid. Converting to AC current</p><p>involves a power loss.</p><p>The capacity of cells to convert light into electricity is defined by</p><p>watts peak (Wp). This is based on a bench test and is the power generated</p><p>by a PV under light intensity of 1000 watts per square metre, equivalent</p><p>to bright sun. The efficiency of a cell is a function of both peak output</p><p>and area. This is a laboratory measurement and does not necessarily</p><p>give a true indication of energy yield.</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 81</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>82</p><p>At the time of writing the most efficient PVs are monocrystalline</p><p>silicon consisting of wafers of a pure crystal of silicon. They achieve a</p><p>peak output of about 15 per cent. That means that 15 per cent of day-</p><p>light is converted to electricity when daylight is at its maximum intensity.</p><p>Due to the production processes involved these cells are expensive.</p><p>The solar cell size of around 10 cm � 10 cm has a peak output of</p><p>about 1.5 watts. To realise a usable amount of electricity cells are wired</p><p>into modules which, in turn, are electrically connected to form a string.</p><p>One or more strings form an array of modules.</p><p>The cells are sandwiched between an upper layer of toughened</p><p>glass and a bottom layer of various materials including glass, Tedlar or</p><p>aluminium. It must be remembered that a number of linked cells pro-</p><p>duces a significant amount of current, therefore during installation solar</p><p>cells should be covered whilst all the electrical connections are made.</p><p>Polycrystalline silicon</p><p>In the production process of this cell, molten silicon is cast in blocks</p><p>containing random crystals of silicon. In appearance cells are blue and</p><p>square. It is cheaper than a monocrystalline cell but has a lower effi-</p><p>ciency ranging between 8 and 12 per cent.</p><p>A variation of silicon technology has been developed by Spheral</p><p>Solar of Cambridge, Ontario. It consists of 1 mm diameter silicon balls</p><p>made from waste silicon from the chip making industry. The core of each</p><p>sphere is doped to make it a p-type semi-conductor and the outer surface</p><p>to make it an n-type semi-conductor. Each sphere is therefore a miniature</p><p>Figure 7.2</p><p>Photovoltaic cell structure and</p><p>function</p><p>n-doped silicon Glass cover</p><p>Solar radiation</p><p>Electrodes</p><p>Movement of electrons</p><p>p-doped silicon</p><p>Substrate backing</p><p>Space-charge zone</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 82</p><p>DOMESTIC ENERGY</p><p>83</p><p>PV cell. The spheres are contained within a flexible aluminium and plastic</p><p>matrix producing an effect similar to blue denim. The system has a</p><p>claimed efficiency of 11 per cent and can be formed to almost any profile,</p><p>which should make it attractive to architects. It is planned to market it</p><p>during 2005.</p><p>Amorphous silicon</p><p>This cell does not have a crystalline structure but is stretched into thin</p><p>layers which can be deposited on a backing material which can be rigid</p><p>or flexible. It is the first of a new breed of PVs based on thin film technol-</p><p>ogy. By building up layers tuned to different parts of the solar spectrum</p><p>known as a double or triple junction cell, a peak efficiency of 6 per cent is</p><p>achievable. Unlike the crystalline cells it is capable of bulk production and</p><p>is therefore potentially much cheaper.</p><p>Cadmium telluride (CdTe) and copper indium</p><p>diselenide (CIS)</p><p>These cells are a further development of thin film technology, having</p><p>efficiencies of about 7 per cent and 9 per cent respectively. At present</p><p>prices are comparatively high but will reduce as volume of sales increases.</p><p>In summary, costs range between £2 and £4 per Wp. However, unit</p><p>cost is not necessarily the only criterion. Different cells have varying</p><p>optimum conditions which has been highlighted by a research pro-</p><p>gramme recently completed by the Oxford University Environmental</p><p>Change Institute. This showed that the amount of electricity generated</p><p>by a PV array rated at 1 kWp in one year varies considerably between</p><p>different technologies. For example, CIS (Seimens ST 40) gave the best</p><p>returns at over 1000 kWh per kWp per year in the UK. Double junction</p><p>amorphous silicon cells were close behind. This is because these cells</p><p>are more effective in the cloudy conditions so prevalent in the UK.</p><p>Single junction amorphous silicon cells were the poorest performers.</p><p>The best performing modules produced nearly twice as much power as</p><p>the lowest yielding cells, so it is very much a case of ‘buyer beware’.</p><p>A sloping roof facing a southerly direction is the ideal situation, pro-</p><p>vided it is not overshadowed by trees or other buildings. However, east</p><p>and west orientations can produce significant</p><p>amounts of electricity. The</p><p>optimum angle of tilt depends on latitude. In London it is 35�. As a rough</p><p>guide, in London 1 square metre of monocrystalline PVs could produce</p><p>111 kWh of electricity per year. On low pitch or flat roofs it is advisable to</p><p>mount the cells on tilt structures at the correct orientation. However, in the</p><p>UK climate, a flat roof can still deliver 90 per cent of the optimum output.</p><p>Standard PV modules can easily be fixed to an existing roof.</p><p>However, if a roof covering needs to be replaced, it then could become</p><p>a cost-effective option to use solar slates, tiles or shingles to maintain a</p><p>traditional appearance.</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 83</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>84</p><p>A housing project which integrates PVs into its elevations and roofs is</p><p>the Beddington Zero Energy Development (BedZED) in the London</p><p>Borough of Sutton, designed by Bill Dunster with Arup as the services</p><p>engineers. Originally the intention was to use their power to meet the</p><p>needs of the buildings. The problem was the extent of the expected</p><p>payback time at current low energy prices. Their purpose is now to provide</p><p>battery charging for a pool of electric vehicles for the residents which has</p><p>the advantage of avoiding conversion to AC current (Figure 7.4).</p><p>It is important to ventilate PV cells since their efficiency falls as temper-</p><p>ature increases. This requirement has been put to good use in a restaurant</p><p>Figure 7.4</p><p>Southern elevation, BedZED housing</p><p>development, South London</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 84</p><p>DOMESTIC ENERGY</p><p>85</p><p>Figure 7.5</p><p>Diagrams of PV heat recovery system</p><p>(courtesy of CADDET)</p><p>in North Carolina, USA. Its integrated roof system has 32 amorphous PV</p><p>modules serving a 20 kWh battery facility. This supplements demand at</p><p>peak times and also bridges interruptions in the grid supply.</p><p>What makes this system special is the fact that warmth that builds</p><p>up under the cells is harnessed to heat water which supplements space</p><p>heating. A fan circulates air through a series of passages beneath the</p><p>modules. As solar heat builds up, the fan cuts in automatically to circu-</p><p>late heat away from the PVs and direct it in a closed loop to a heat</p><p>exchanger. This technology will save the restaurant about $3000 per</p><p>year in utility and hot water costs, at the same time avoiding 22 680 kg</p><p>of CO2 emissions (Figure 7.5). See also Figure 18.16, p. 234.</p><p>Solar radiation</p><p>Photovoltaic modules</p><p>Electricity generated from</p><p>photovoltaic modules</p><p>PV modules</p><p>Hot air</p><p>from</p><p>modules</p><p>Cold water in</p><p>Heat exchanger</p><p>Hot water circulates</p><p>to pre-heat tanks</p><p>Pump</p><p>Solar</p><p>pre-heat</p><p>tank</p><p>Hot</p><p>water</p><p>heater</p><p>Hot water out</p><p>Cool air into modules</p><p>Fan</p><p>PV modules</p><p>Cool air in</p><p>Warm air out</p><p>Air circulated</p><p>behind modules</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 85</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>86</p><p>Energy output</p><p>The energy output from a monocrystalline cell varies with insolation level</p><p>in an almost linear fashion across its operating range. Output is adversely</p><p>affected by high operating temperature with a drop in efficiency from</p><p>about 12 per cent at 20�C to about 10 per cent at 50�C.</p><p>Photovoltaic panels would need active cooling in many building</p><p>situations to maintain maximum output during summer months.</p><p>Clearly this is impractical and costly and at present the drop in effi-</p><p>ciency has to be accepted. An alternative is to encourage ventilation of</p><p>the panels by suitable design of their location and position in order to</p><p>permit air flow and natural ventilation cooling to front and, if possible,</p><p>rear of the array.</p><p>Since most uses of electricity require alternating current (AC), as</p><p>stated earlier, an inverter must be employed. However, in the US PVs</p><p>are now available from the Applied Power Corporation which deliver</p><p>AC electricity which means they can be connected directly to the grid.</p><p>An AC inverter is integrated with the cells (CADDET Renewable Energy</p><p>Newsletter, March 2000).</p><p>It is often the case that the supply of electrical energy is not con-</p><p>current with demand, perhaps because of occupancy and use patterns.</p><p>In such situations two alternatives exist: either the excess power can be</p><p>stored in some form of battery or used to heat water to be stored in an</p><p>insulated tank to provide space heating. Alternatively it can simply be</p><p>offloaded to the electricity grid. The former of these options causes an</p><p>energy loss in the conversion process and additionally requires the pro-</p><p>vision of a suitable and substantial battery store. The preferred option</p><p>in most urban situations at the present time is the grid-connected sys-</p><p>tem, though a sophisticated control system is required to ensure the</p><p>output matches the grid phase. This also provides a backup supply</p><p>when PV generation is insufficient. A major drawback at present is the</p><p>price at which the utility companies purchase the excess PV production.</p><p>Pressure is mounting for the adoption of reversible meters that</p><p>accumulate credit units from a renewable on-site installation but this is</p><p>being resisted by some energy companies. The UK has some of the</p><p>worst buy-back rates in Europe, currently about 5 p per unit as against</p><p>the utility price of approximately 15 p. A combination of high capital</p><p>cost and miserly buy-in rates is seriously undermining the adoption of</p><p>this technology by householders in the UK in contrast to Germany</p><p>where subsidised demand is outstripping manufacturing capacity.</p><p>It may be easier to justify the cost of PV cladding materials for</p><p>commercial buildings where occupancy patterns coincide with peak</p><p>production levels.</p><p>PV cladding materials can now be obtained in different patterns</p><p>and colours depending upon the nature of the cells and the backing</p><p>material to which they are applied. This offers an increasing range of</p><p>facade options which might be exploited by architects to create</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 86</p><p>DOMESTIC ENERGY</p><p>87</p><p>particular aesthetic effects. Thin film photovoltaic systems, which</p><p>basically have a layer of a coating layer applied to glass, look particularly</p><p>promising.</p><p>In the Netherlands PV cells are being mounted on motorway</p><p>sound barriers. The UK Highways Agency gave approval in 2004 for PVs</p><p>to be mounted in panels alongside motorways. A pilot project array has</p><p>been installed on the M27 in Hampshire to feed directly into the</p><p>national grid.</p><p>Micro-combined heat and power (CHP)</p><p>It is interesting how two nineteenth century technologies, the Stirling</p><p>engine and the fuel cell, are only now coming into their own. Invented</p><p>by Robert Stirling in 1816, the engine that bears his name is described</p><p>as an ‘external combustion engine’. This is because heat is applied to</p><p>the outside of the unit to heat up a gas within a sealed cylinder. The</p><p>heat source is at one end of the cylinder whilst the cooling takes place</p><p>at the opposite end. The internal piston is driven by the successive</p><p>heating and cooling of the gas. When the gas is heated it expands,</p><p>pushing down the piston. In the process the gas is cooled and then</p><p>pushed to the heated top of the cylinder by the returning piston, once</p><p>again to expand and repeat the process. Because of advances in pis-</p><p>ton technology and in materials like ceramics from the space industry</p><p>and high temperature steels allowing temperatures to rise to 1200�C,</p><p>it is now considered a firm contender for the micro-heat-and-power</p><p>market.</p><p>Heat can be drawn off the engine to provide space heating for a</p><p>warm air or wet system. Alternatively it can supply domestic hot water.</p><p>In one system on the market, ‘Whispergen’, the vertical motion of the</p><p>piston is converted to circular motion to power a separate generator.</p><p>MicroGen is currently conducting trials of a Stirling CHP system in</p><p>which the generator is contained within the cylinder. At the heart of the</p><p>system is a unique technology developed by Sunpower in the US. This</p><p>consists of a sealed chamber containing a single piston integrated with</p><p>an alternator. At the top of the piston there is a magnate which interacts</p><p>with the alternator coil to produce electricity at</p><p>240 volts single phase.</p><p>(Figure 7.6)</p><p>The top of the chamber is heated to a temperature of 500�C whilst</p><p>the lower part is water cooled to 45�C creating the necessary pressure</p><p>difference in the captive gas. The MicroGen unit is designed to pro-</p><p>duce 1.1 kW of electricity which is considered to be adequate for base</p><p>load for most domestic requirements. Any further load will be drawn</p><p>from the grid in the normal way.</p><p>Because the system is strictly controlled to 240 volts and 50 Hz it is</p><p>compatible with mains electricity and therefore it is claimed that it can</p><p>be linked directly to the domestic ring main. It will be possible to feed</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 87</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>88</p><p>excess electricity to the grid. The four phases of the Stirling cycle are</p><p>explained in Figure 7.6.</p><p>As regards the warming function, the heat which is drawn off by the</p><p>water coolant is reinforced by heat from the flue gases extracted by a</p><p>heat exchanger. There is a supplementary heating element in the sys-</p><p>tem for occasions when demand exceeds the output from the engine.</p><p>The heat is transmitted either to a condensing or combi-boiler. There</p><p>are three heat output options ranging from 15 kW (51 000 btu/h) to</p><p>36 kW (122 000 btu/h). All models will be able to reduce their heating</p><p>output to 5 kW when necessary. It is expected that future models will be</p><p>adapted to serve warm air heating systems. There is also the possibility</p><p>of creating a multiple unit system to provide increased power and heat</p><p>at a commercial scale.</p><p>Because there is only one moving part within the closed chamber</p><p>the Stirling engine requires no maintenance. The boiler element needs</p><p>the same level of maintenance as a conventional boiler.</p><p>The cost estimate is that the system will pay back the additional</p><p>cost over and above a conventional boiler in 4–5 years.</p><p>The unit is compact, can fit between modular kitchen units and</p><p>creates a noise level comparable to an average refrigerator (Figure 7.7).</p><p>Despite some current regulatory problems in the UK the Depart-</p><p>ment of Environment, Transport and the Regions is optimistic about the</p><p>prospects for micro-CHP or ‘micro-cogeneration’, estimating the</p><p>potential domestic market to be up to 10 million units. With the open-</p><p>ing up of the energy markets, micro-CHP is likely to become a major</p><p>player in the energy stakes, accounting for some 25–30 GW of electric-</p><p>ity (GWe). One of the factors favouring this technology is that it can be</p><p>up to 90 per cent efficient and result in a reduction in total carbon diox-</p><p>ide emissions of up to 50 per cent when compared with the separate pro-</p><p>duction of heat and energy. Large power stations are about 30 per cent</p><p>Figure 7.6</p><p>Four phases of the Stirling engine</p><p>cycle</p><p>P</p><p>is</p><p>to</p><p>n</p><p>Expanding gas Contracting gas</p><p>Heat out</p><p>through</p><p>water</p><p>cooling</p><p>Heat in</p><p>from gas</p><p>burnerDisplacer</p><p>piston</p><p>Alternator</p><p>power</p><p>piston</p><p>Planar spring keeps</p><p>displacer</p><p>moving up and down</p><p>Water cooling coupled</p><p>with heat</p><p>creates a pressure wave</p><p>Alternator generates</p><p>electricity and also</p><p>kick-starts the engine</p><p>The displacer moves gas</p><p>from the hot to the cold</p><p>end of the chamber</p><p>whether expanding or</p><p>contracting</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 88</p><p>DOMESTIC ENERGY</p><p>89</p><p>efficient. Add to this line losses of 5–7 per cent and it is obvious there is</p><p>no contest.</p><p>In summary, the advantages of micro-CHP or micro-cogeneration are:</p><p>● It is a robust technology with few moving parts.</p><p>● Maintenance is simple, consisting of little more than cleaning the</p><p>evaporator every 2000–3000 hours (on average once a year).</p><p>● Since there is no explosive combustion the engine produces a noise</p><p>level equivalent to a refrigerator.</p><p>● It is compact with a domestic unit being no larger than an average</p><p>refrigerator.</p><p>● It operates on natural gas, diesel or domestic fuel oil. In the not</p><p>distant future machines will be fuelled by biogas from the anaerobic</p><p>digestion of waste.</p><p>● The efficiency is up to 90 per cent compared with 60 per cent for a</p><p>standard non-condensing boiler.</p><p>● Unlike a boiler it produces both heat and electricity, reducing</p><p>energy use by about 20 per cent and saving perhaps £200–£300 on</p><p>the average annual electricity bill.</p><p>● It can be adapted to provide cooling as well as heat.</p><p>The UK government is keen to promote this technology and it is always</p><p>worth checking if grants are available. The best source of advice is the</p><p>Energy Saving Trust (www.est.org.uk).</p><p>Figure 7.7</p><p>MicroGen kitchen wall-mounted unit</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 89</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>90</p><p>Figure 7.8</p><p>Electrolyser at West Beacon Farm</p><p>Fuel cells</p><p>Looking towards the next decade, the source of heat and power for</p><p>many homes could well be the fuel cell. This is an electrochemical</p><p>device which feeds on hydrogen to produce electricity, heat and water</p><p>(see Chapter 13 ‘Energy options’). In January 2004 the first UK domestic-</p><p>scale fuel cell began operation at West Beacon Farm in Leicestershire.</p><p>The most common fuel cell at the moment is the proton exchange</p><p>membrane type (PEMFC) which feeds on pure hydrogen. It has an</p><p>operating temperature of 80�C and at the moment is 30 per cent effi-</p><p>cient. This is expected to improve to 40 per cent.</p><p>The farm is owned by the energy innovator Professor Tony</p><p>Marmont. Rupert Gammon of Loughborough University is the project</p><p>leader as part of the Hydrogen and Renewables Integration Project</p><p>(HARI). It is designed to provide entirely clean energy.</p><p>The hydrogen is extracted from water by means of an electrolyser</p><p>which splits water into oxygen and hydrogen by means of an electric</p><p>current (Figure 7.8).</p><p>The electricity for the electrolyser is provided by wind, PV and</p><p>micro-hydro generation. An alternative is to extract H2 from natural gas</p><p>by means of a reformer but then it is no longer zero carbon.</p><p>The fuel cell installation is compact and can fit into a cupboard. It</p><p>has no moving parts and is therefore almost silent. At the moment it is</p><p>producing 2 kW electricity and 2 kW heat. A second 5 kW fuel cell from</p><p>Plugpower is in the process of being commisioned (Figure 7.9).</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 90</p><p>DOMESTIC ENERGY</p><p>91</p><p>The production and storage of hydrogen as the energy carrier are</p><p>the problems still to be solved satisfactorily. Cracking water into hydro-</p><p>gen and oxygen by electricity is analogous to the sledge hammer and</p><p>the nut. An alternative method of producing hydrogen is to extract it</p><p>from ethanol derived from biowaste as has recently been demonstrated</p><p>at the University of Minnesota.</p><p>The reactor is, in effect, a compact fuel cell hydrogen generator</p><p>which would be ideal for vehicle application. It can be scaled up to pro-</p><p>vide the hydrogen for grid-connected fuel cells using ethanol fer-</p><p>mented from both biowaste and energy crops.</p><p>Sanyo plans to launch a domestic fuel cell using natural gas or</p><p>propane in 2005. It will be used to power TVs, air conditioners,</p><p>refrigerators and PCs as well as catering for domestic hot water require-</p><p>ments. It plans to export the system to the US and Europe. Other com-</p><p>panies like Mitsubishi Heavy Industries Ltd and Matsushita Electrical</p><p>Industrial Co. are developing a similar system also due on the market</p><p>in 2005.</p><p>Currently under development is a microbial fuel cell which avoids</p><p>the need for hydrogen. It converts sewage to electricity. Bacterial</p><p>enzymes break down the sewage liberating protons and electrons. The</p><p>system then behaves like a proton exchange membrane fuel cell with</p><p>protons passing through the membrane and electrons diverted to an</p><p>external circuit to provide useful electricity (see pp. 255–256).</p><p>Embodied energy and materials</p><p>It is not just the energy consumed during the life of a building which has</p><p>to be considered. Energy is involved in the extraction, manufacture and</p><p>Figure 7.9</p><p>Fuel cell installation, West Beacon</p><p>Farm (courtesy of Intelligent Energy</p><p>2004)</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 91</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>92</p><p>transportation of building materials and this is known as the ‘embodied</p><p>energy’ and directly relates to the gross carbon intensity of a material.</p><p>The overall environmental credentials of a building are affected by</p><p>a number of factors:</p><p>● energy used over its estimated lifetime;</p><p>● energy used in the construction process;</p><p>● the extent to which recycled materials have been used (see</p><p>Chapter 18);</p><p>● the presence of pollutants in a material such as volatile organic</p><p>compounds (VOCs);</p><p>● toxic substances used in the production process;</p><p>● energy used in demolition;</p><p>● level of recyclable materials at demolition;</p><p>● materials used in refurbishment.</p><p>At the moment the consensus is that a building consumes much</p><p>more energy during its lifetime than is involved in extraction, manufac-</p><p>ture and transportation. However, it will increasingly be the case that</p><p>the embodied energy will be a significant fraction of the total as build-</p><p>ings become more energy efficient. It can still be difficult to assess the</p><p>full impact at present because of the scarcity of detailed information.</p><p>This arises from a natural reluctance on the part of manufacturers to dis-</p><p>close too much information about their commercial processes and also</p><p>because of natural variations in techniques, which can lead to a wide</p><p>band of values for similar products.</p><p>It is clear, however, that the area of materials energy and environ-</p><p>mental effect is one which can only grow in coming years. It is also a</p><p>sphere where much more information is required in order to exploit</p><p>opportunities associated with carbon taxes and other fiscal measures to</p><p>improve design. A number of assessment tools and techniques are</p><p>becoming available.</p><p>AIAC-Ch07.qxd 03/25/2005 17:15 Page 92</p><p>93</p><p>Chapter</p><p>Eight</p><p>Advanced and ultra-low</p><p>energy houses</p><p>Besides designing the Autonomous House in Southwell, the Vales</p><p>designed a group of ultra-low energy houses at Hockerton in</p><p>Nottinghamshire. This is a narrow plan single aspect group of houses</p><p>fully earth sheltered on the north side with the earth carried over the</p><p>roof. The south elevation is completely occupied by a generous sun-</p><p>space across all the units.</p><p>This is designed to be a partially autonomous scheme using recy-</p><p>cled grey water and with waste products being aerobically treated by</p><p>reed beds. A wind generator supplements its electricity needs. It is</p><p>described as a net zero energy scheme which is defined as a develop-</p><p>ment which is connected to the grid and there is at least a balance</p><p>between the exported and imported electricity. There is an imbalance</p><p>in cost for reasons stated earlier. A development that meets all its elec-</p><p>tricity needs on site and therefore is not connected to the grid is an</p><p>autonomous development.</p><p>Hockerton is a project designed for a special kind of lifestyle which</p><p>will only ever have minority appeal. For example, it plans to be self-</p><p>sufficient in vegetables, fruit and dairy products employing organic-</p><p>permaculture principles. One fossil fuel car is allowed per household</p><p>and 8 hours’ support activity per week is required from each resident.</p><p>This would not be to everyone’s taste, but it is important to demonstrate</p><p>just how far things can be taken in creating architecture that harmonises</p><p>with nature (Figures 8.1 and 8.2, 5.3 and 5.4).</p><p>It has a number of key features:</p><p>● ninety per cent energy saving compared with conventional housing;</p><p>● self-sufficient in water with domestic water collected from the conser-</p><p>vatory roof and reed bed-treated effluent for purposes that require</p><p>the EU bathing water standard;</p><p>● considerable thermal storage due to earth sheltering;</p><p>● seventy per cent heat recovery from extracted warm air;</p><p>● triple glazed internal windows and double glazed conservatory;</p><p>● 300 mm of insulation in walls;</p><p>● a wind generator will reduce reliance on the grid;</p><p>● roof-mounted photovoltaics.</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 93</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>94</p><p>The Beddington Zero Energy Development –</p><p>BedZED</p><p>The Innovative Peabody Trust commissioned this development as an</p><p>ultra-low energy mixed use scheme in the London Borough of Sutton.</p><p>It consists of 82 homes, 1600 m2 of work space, a sports club, nursery,</p><p>organic shop and health centre, all constructed on the site of a former</p><p>sewage works – the ultimate brownfield site. Peabody was able to</p><p>countenance the additional costs of the environmental provisions on</p><p>the basis of the income from the offices as well as the homes. Though</p><p>the Trust is extremely sympathetic to the aims of the scheme, it had to</p><p>stack up in financial terms. It is described in detail in Chapter 18 ‘State</p><p>of the art case studies’.</p><p>The David Wilson Millennium Eco-House</p><p>A demonstration Eco-House has been built in the grounds of the</p><p>School of the Built Environment, University of Nottingham (Figure 8.3).</p><p>It is designed as a research facility and a flexible platform for the range</p><p>of systems appropriate to housing. Its features are:</p><p>● PV tiles integrated into conventional slates providing 1250 kWh/year;</p><p>● solar collectors of the vacuum tube type on the south elevation to</p><p>meet the demand for domestic hot water;</p><p>● light pipe illuminating an internal bathroom and providing natural</p><p>ventilation;</p><p>Figure 8.1</p><p>Earth sheltered south and solar west</p><p>elevations</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 94</p><p>ADVANCED AND ULTRA-LOW ENERGY HOUSES</p><p>95</p><p>● solar chimney to provide buoyancy ventilation in summer and passive</p><p>warmth in winter;</p><p>● helical wind turbine;</p><p>● ground source heat pump to supplement space heating.</p><p>The output from the energy systems is constantly monitored.</p><p>Associated with the Eco-House are several free-standing sun-tracking</p><p>PV panels tilted to the optimum angle.</p><p>Demonstration House for the Future,</p><p>South Wales</p><p>A competition winning ‘House for the Future’ has been designed</p><p>by Jestico Wiles within the grounds of the Musuem of Welsh Life in</p><p>Water saving WC</p><p>PVC-free wiring</p><p>and pipes</p><p>throughout house</p><p>This house has a TV and</p><p>video like any other</p><p>Low-energy</p><p>light bulbs</p><p>Showers are</p><p>fitted, not baths</p><p>Water pours from taps</p><p>as in normal houses</p><p>Glass, plastic and cans</p><p>are recycled</p><p>Eco-Balls used for washing</p><p>clothes, not detergents</p><p>1</p><p>6 6</p><p>Key to rooms</p><p>1 Conservatory</p><p>2 Kitchen</p><p>3 Utility room</p><p>4 Dining area</p><p>6 Bedrooms</p><p>7 Bathroom</p><p>5 Living room</p><p>Five families teamed up to build the row</p><p>of houses in Hockerton, Nottinghamshire,</p><p>designed by architects Robert and</p><p>Brenda Vale</p><p>A wind turbine</p><p>would provide</p><p>electricity, but</p><p>needs planning</p><p>approval</p><p>Each adult contributes</p><p>16 hours a week on</p><p>tasks like organic</p><p>gardening</p><p>Diverse plants and animals</p><p>are encouraged 5,000 native</p><p>trees have been planted and</p><p>60 species of birds recorded</p><p>Waste water is dealt with by Hockerton's</p><p>own mini-sewage farm at the side of the</p><p>large artificial lake. Once treated it runs into</p><p>the lake and becomes food for the fish</p><p>Rainwater for drinking</p><p>and washing is stored</p><p>in tanks and a reservoir</p><p>The families try to walk and</p><p>cycle rather than use cars, and</p><p>plan to buy an electic vehicle</p><p>Soil covered</p><p>roofs and</p><p>planting hide</p><p>the house</p><p>from the road</p><p>Figure 8.2</p><p>Hockerton overall life-style</p><p>specification</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 95</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>96</p><p>Figure 8.3</p><p>David Wilson Millennium Eco-House,</p><p>Nottingham University</p><p>South Wales. Its two key attributes are sustainability and flexibility. It is</p><p>capable of occupying a variety of situations: a rural location, a green-</p><p>field suburban site or high density urban sites in terrace form.</p><p>The structure of the house consists of a post and beam timber</p><p>frame prefabricated from locally grown oak. A superinsulated timber</p><p>stud wall faced with oak boarding and lime render occupies three sides</p><p>of the building. The void between the timbers is filled with 200 mm of</p><p>sheep’s wool, specially treated, giving a U-value of 0.16 W/m2K.</p><p>Internally much of the space is defined by non-load bearing stud parti-</p><p>tions, allowing total flexibility and adaptability. There are some earth</p><p>block partitions on the ground floor using clay found on the site. These</p><p>provide thermal mass, supplementing the thermal storage</p><p>properties</p><p>of the concrete floor slab. All materials were selected with a view to</p><p>minimising embodied energy (Figures 8.4 to 8.6).</p><p>The north facing roof is covered with sedum plants laid on a recy-</p><p>cled aluminium roof. Cellulose fibre provides 200 mm of insulation</p><p>between the deep rafters giving the roof a U-value of 0.17 W/m2K. This</p><p>insulation is manufactured from recycled paper and treated with borax</p><p>as a flame and insect retardant.</p><p>Considerable south facing glazing provides substantial amounts</p><p>of passive solar energy. Windows on the south elevation are designed</p><p>to change according to the seasons of the year.</p><p>As regards the plan, living space is fluid to accommodate the</p><p>needs of different occupants. Open living and daytime spaces face</p><p>south whilst more private cellular spaces are on the north side. The</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 96</p><p>Figure 8.5</p><p>Internal views obtained by</p><p>Architectural Press</p><p>Figure 8.4</p><p>House for the Future – cross-section</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 97</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>98</p><p>number of bedrooms can vary from one to five according to family</p><p>needs. The house can contract as well as expand.</p><p>The energy regime makes maximum use of both passive and active</p><p>solar systems. Space heating can be supplemented by a ground source</p><p>heat pump fed by a 35 m bore hole. A heat pump is driven by electricity</p><p>but one unit of electricity produces 3.15 units of heat. A pellet burning</p><p>wood stove rounds off the space heating. Gas is not available on the site.</p><p>Roof-mounted solar collectors provide water heating for most of</p><p>the year and a ridge-mounted wind generator and a PV array produc-</p><p>ing 800 W go some way to meeting the electricity demand. When</p><p>renewable energy technologies become more affordable the house</p><p>will become self-sufficient in energy.</p><p>Finally, water conservation measures are an important component</p><p>of its ecological credentials. Rainwater is collected in a specially</p><p>enlarged gutter which can store 3 m3. It is mechanically filtered and</p><p>gravity fed to toilets and washing machine. This should meet about</p><p>25 per cent of an average family’s demand.</p><p>The prospects for wood</p><p>The House of the Future raises the question of the structural use of timber</p><p>in buildings. Timber scores well on the sustainability scale, provided it is</p><p>obtained from an accredited source such as the Forestry Stewardship</p><p>Council. The Weald and Downland Open Air Museum 7 miles north of</p><p>Chichester is a national centre for the conservation and study of traditional</p><p>timber-framed buildings. The Conservation Centre explores new tech-</p><p>niques in greenwood timber construction. Edward Cullinan Architects in</p><p>association with Buro Happold Engineers have produced an undulating</p><p>structure which rhymes with the South Downs landscape. The timber</p><p>structure comprises a clear span gridshell formed out of a weave of oak</p><p>laths. The high moisture content of the timber allows it to be formed into</p><p>the necessary curves and then locked into shape. Once the laths are in</p><p>place natural drying strengthens the structure. Oak is twice as strong as an</p><p>equivalent size of other timbers which means that the cross-section of</p><p>members can be reduced. The longest laths are 37 metres. Unique to the</p><p>structure is the green jointing of the gridshell laths from freshly sawn oak.</p><p>It is developments in glue technology which have made this possible.</p><p>The structure is set on an earth sheltered masonry ground floor. The</p><p>lower storey is temperature controlled to safeguard archival material.</p><p>A central row of glue-laminated columns supports the floor of the</p><p>workshop.</p><p>This is the first timber gridshell structure in Britain and should</p><p>become an icon of sustainable construction (Figure 8.7).</p><p>An even more ambitious gridshell structure is taking shape in</p><p>Savill Garden in Windsor Great Park. Architects Glenn Howells won a</p><p>competition for a visitor centre with a wave form grid structure that</p><p>Figure 8.6</p><p>Ground and first floor</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 98</p><p>ADVANCED AND ULTRA-LOW ENERGY HOUSES</p><p>99</p><p>differs from the Weald and Downland building in that it is raised above</p><p>ground, allowing panoramic views of the park. It will be the largest grid-</p><p>shell structure in the UK at 90 m long and 25 m wide. The structure has</p><p>been designed by Buro Happold, the engineers involved at Weald and</p><p>Downland, using 80 by 50 mm larch timbers harvested from the Park</p><p>with oak forming the outer rainscreen.</p><p>As a research exercise in multi-storey timber buildings, the</p><p>Building Research Establishment Centre for Timber Technology and</p><p>Construction has built a six-storey timber-framed apartment block as a</p><p>test facility in its vast airship hangar at Cardington (Figure 8.8). The</p><p>results of the tests may well have a profound impact on the house build-</p><p>ing industry. The building comprises:</p><p>● four flats per floor;</p><p>● a plan-aspect ratio of c.2:1;</p><p>● platform timber frame;</p><p>● timber protected shaft;</p><p>● single timber stair and lift shaft;</p><p>● brick cladding.</p><p>The report on the project concludes:</p><p>This high profile project has provided a unique opportunity to</p><p>demonstrate the safety, benefits and performance of timber</p><p>frame construction technologies. This project has brought all</p><p>aspects of construction together, including Regulations,</p><p>Figure 8.7</p><p>Interior of the Weald and Downland</p><p>Conservation Centre (Edward Cullinan</p><p>and Partners)</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 99</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>100</p><p>Research, Design, Construction and Whole Building</p><p>Evaluation. Many Building Regulations, codes and standards</p><p>are being updated as a result of this project. It has been the</p><p>most challenging and exciting opportunity to obtain technical</p><p>backup data for promotion of timber frame in the last 20 years</p><p>and it has been recognised as one of the most valued projects</p><p>(Enjily, V. (2003) Performance Assessment of Six-Storey Timber</p><p>Frame Buildings against the UK Building Regulations, BRE</p><p>Garston)</p><p>A tour de force of timber construction is the recently completed</p><p>Sibelius Hall at Lahti in Finland. This concert hall epitomises how timber</p><p>used both as a structural and sheeting material can produce a building</p><p>great elegance and beauty. It is a testimony to the mastery of timber</p><p>developed by the Finns over the centuries and serves to exemplify</p><p>the versatility of this material as the ultimate renewable resource for</p><p>construction. The architects are Hanna Tikka and Kimmo Lintula.</p><p>As well as being a renewable resource, timber also has a good</p><p>strength to weight ratio, which is why it was used to construct one of the</p><p>most famous aircraft of the Second World War, the Mosquito. The</p><p>designers of this aircraft pioneered timber monocoque construction in</p><p>which the skin and framework as a unified whole coping with both com-</p><p>pression and tension. The advantage is this system is that it can accom-</p><p>modate curved and flowing shapes combining lightness with strength.</p><p>The main structural element is laminated veneered lumber (LVL) typically</p><p>Figure 8.8</p><p>Building Research Establishment</p><p>experimental timber-framed</p><p>apartments</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 100</p><p>ADVANCED AND ULTRA-LOW ENERGY HOUSES</p><p>101</p><p>Figure 8.9</p><p>Roof formation, the Maggie Centre,</p><p>Dundee (courtesy of RIBA Journal)</p><p>Figure 8.10</p><p>Maggie Centre, Dundee. RIBA Building</p><p>of the Year for 2004</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 101</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>102</p><p>made from Norwegian spruce. It can be produced in sheets up 26 m long</p><p>by using staggered and scarf jointing.</p><p>Timber can even accommodate the fluid imagination of Frank</p><p>Gehry. LVL was chosen for the roof of the Maggie Centre in Dundee.</p><p>It is finished in stainless steel (Figures 8.9 and 8.10).</p><p>The Winter Gardens form a spectacular element of the ‘heart of</p><p>the city’ project for Sheffield (Figure 8.11). It is conceived partly as a</p><p>glazed street in the spirit of the galleria connecting with the wider</p><p>urban structure. It opens at right angles to the Millennium Galleries that</p><p>also integrate a pedestrian route with gallery and restaurant provision.</p><p>The contrasting</p><p>space and architectural expression of the two buildings</p><p>achieve the height of the poetic in urban terms. The most striking</p><p>feature is the laminated larch parabolic arches which support the glass</p><p>skin forming a counterpoint to the trees within. Larch was chosen for its</p><p>Figure 8.11</p><p>Winter Gardens, Sheffield 2002</p><p>(architects: Pringle Richards Sharratt)</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 102</p><p>ADVANCED AND ULTRA-LOW ENERGY HOUSES</p><p>103</p><p>InfiltrationPositive pressure Negative pressure</p><p>durability and minimal maintenance characteristics. In time it will turn a</p><p>silvery grey.</p><p>The space is 65.5 m long and 22 m wide and designed to accom-</p><p>modate a wide variety of exotic plants, many of which are under threat,</p><p>in a frost-free environment. Underfloor heating in winter is provided by</p><p>the city centre district low grade heating scheme. In summer surround-</p><p>ing buildings will provide solar shading. Vents in the roof and at both</p><p>ends of the building encourage stack effect ventilation. Trees such as</p><p>Norfolk Island Pine and New Zealand Flax occupy the highest central</p><p>zone of the space which rises to 22 m. For the citizens of Sheffield it has</p><p>been a spectacular success.</p><p>A useful guide to designing in timber is provided by Willis, A.-M.</p><p>and Toukin, C. (1998) Timber in Context – A Guide to Sustainable Use,</p><p>NATSPEC 3 Guide.</p><p>The external environment</p><p>● Wind</p><p>● Rain</p><p>● Solar shading</p><p>● Evaporative cooling.</p><p>The orientation of a property can have a significant impact on the</p><p>extent to which it is adversely affected by wind. This can create a pres-</p><p>sure difference between the faces of a building: positive on the wind-</p><p>ward side and negative on the lee face. This means that cold air tends</p><p>to be forced into the windward elevation and warmth sucked out of the</p><p>lee side (Figure 8.12).</p><p>The UK has one of the most turbulent climates in Europe. In the UK</p><p>the average wind speed for 10 per cent of the time ranges from 8 to</p><p>about 12.5 metres per second, the higher figures being in Scotland.</p><p>Figure 8.12</p><p>Wind pressure and infiltration</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 103</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>104</p><p>At the same time, average wind speeds increase by 7 per cent for every</p><p>100 m increase in altitude.</p><p>Wind speeds can be considerably reduced by the introduction of</p><p>natural or artificial dampeners. A solid wind break can greatly reduce</p><p>wind speed in its immediate vicinity but beyond that zone will cause</p><p>turbulence. On the other hand, an openwork fence with only 50 per</p><p>cent solid resistance to wind will moderate wind speed over a much</p><p>greater area. At the same time a timber fence of this nature will be less</p><p>likely to become a casualty of gale force winds.</p><p>Natural features can be effective wind breaks. Even low level plant-</p><p>ing creates drag, thereby slowing the wind force. Trees are the best</p><p>option, remembering that deciduous trees are much less effective in</p><p>winter. As a rule of thumb, the distance from a house to a tree break</p><p>should be 4–5 times the height of the trees to optimise the dampening</p><p>effect.</p><p>Climatologists predict that global warming will result in wetter</p><p>winters and much drier summers with droughts a regular occurrence.</p><p>This gives shrubs and trees a further benefit in the degree to which</p><p>they protect from the drying or desiccating effect of wind. According to</p><p>the TV gardening personality Monty Don ‘In the British climate, wind is</p><p>far more of a problem than sunshine and can be drought-inducing in</p><p>the middle of winter when there is not a ray of sunshine to be seen for</p><p>days’ (Observer Magazine, 19 January 2003).</p><p>Wind plus driving rain can affect the thermal efficiency of a prop-</p><p>erty. When brickwork becomes saturated the thermal conductivity of</p><p>brickwork or blockwork increases since moist masonry transmits heat</p><p>more effectively than in a dry condition. This problem would be cured</p><p>with a polymer-based render.</p><p>Summary checklist for the energy efficient</p><p>design of dwellings</p><p>With the predicted growth in the house building sector over the next</p><p>decade it is important that architects exert maximum pressure to</p><p>ensure that new homes realise the highest standards of bioclimatic</p><p>design. The following are recommendations for minimising the use of</p><p>energy and exploiting natural assets.</p><p>Building features</p><p>● In considering the plan a compact building shape reduces heat loss.</p><p>● Some situations may allow for the protection afforded by earth-</p><p>berming and buffer spaces.</p><p>● Heated areas within the dwelling should be isolated from unheated</p><p>spaces by providing insulation in the partitions between such spaces.</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 104</p><p>ADVANCED AND ULTRA-LOW ENERGY HOUSES</p><p>105</p><p>● Glazing must be low emissivity (Low E) double glazing, preferably</p><p>in a timber frame. If metal frames are necessary there should be a</p><p>thermal break between the frame and the glass.</p><p>● Areas of non-beneficial windows should be minimised.</p><p>● The detailing of joints in the building fabric can have a significant</p><p>impact on energy efficiency.</p><p>● Potential cold bridges should be eliminated.</p><p>● Fabric insulation which is significantly better than the minimum</p><p>required by regulation is strongly recommended.</p><p>● Air tightness should achieve a level of at most three air changes</p><p>per hour at 50 pascals pressure in association with heat recovery</p><p>ventilation.</p><p>● Care should be taken in the design of conservatories which should</p><p>be able to be isolated from the main occupied area; at the same</p><p>time account should be taken of probable air flow patterns. The</p><p>heating of conservatories usually results in a net energy deficit.</p><p>Passive solar heat gain</p><p>External considerations:</p><p>● The main facade of a dwelling should face close to south</p><p>( �30� approximately).</p><p>● The spacing between dwellings should be sufficient to avoid</p><p>overshading.</p><p>● Where possible contours should be exploited either to maximise</p><p>solar gain or minimise adverse effects.</p><p>● Areas with particular overheating risk should be considered when</p><p>planning building layout and form.</p><p>● The provision of deciduous trees and shrubs will offer summer</p><p>shade whilst allowing penetration by winter sun.</p><p>The built form</p><p>● The internal layout should place rooms on appropriate sides of the</p><p>building either to benefit from solar heat gain or to avoid it where</p><p>necessary.</p><p>● Shading (externally if possible) should be installed for windows pos-</p><p>ing overheating risk.</p><p>● The effect on heat gain of window frames and glazing bars can be</p><p>significant.</p><p>● In the design and positioning of windows the effect of solar gain</p><p>must be considered in conjunction with daylight design.</p><p>● As a general rule it is desirable to maximise south facing windows</p><p>and minimise north facing windows.</p><p>● High thermal mass construction levels out the peaks and troughs of</p><p>temperature.</p><p>● Internal surfaces should maximise solar heat absorption.</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 105</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>106</p><p>● A conservatory or other buffer space can be used to preheat incoming</p><p>ventilation air.</p><p>Climate change is predicted to increase the risk of flooding from a com-</p><p>bination of rising sea level, increased storm surges, greater precipita-</p><p>tion and river run-down. In areas where there is the probability of flood</p><p>risk special measures should be adopted, for example:</p><p>● Most living accommodation should, if possible, be on the first and</p><p>upper floors.</p><p>● Floor and wall surfaces on the ground floor should be capable of</p><p>recovery from flooding, e.g. tiled finishes.</p><p>● Power sockets should be at least at bench height.</p><p>● Door openings should be water tight for at least 1 m about ground;</p><p>● Windows sills should be at least 1 m above ground.</p><p>● Ventilation grilles and air bricks should be capable of being sealed.</p><p>● Bathrooms should be on the first floor; where they are on the ground</p><p>floor non-return valves should be fitted to WCs.</p><p>● The electrical circuit on the ground floor should be able to be isolated,</p><p>allowing power to be available on upper floors in times of flooding.</p><p>Systems</p><p>● Environmental considerations should be a priority when</p><p>that the present clear evidence of climate change is 90 per cent certain</p><p>to be due to human activity mainly though the burning of fossil-based</p><p>energy. This should be good enough to persuade us that human action</p><p>can ultimately put a brake on the progress of global warming and its</p><p>climate consequences.</p><p>Once the issues are understood, a commitment to renewable</p><p>energy sources and bioclimatic architectural design should become</p><p>unavoidable. Inspiring that commitment is the purpose of the first part</p><p>of the book which then goes on to illustrate the kind of architecture that</p><p>will have to happen as part of a broader campaign to avert the apoca-</p><p>lyptic prospect of catastrophic climate change.</p><p>The carbon cycle</p><p>Carbon is the key element for life on Earth. Compounds of the element</p><p>form the basis of plants, animals and micro-organisms. Carbon com-</p><p>pounds in the atmosphere play a major part in ensuring that the planet</p><p>is warm enough to support its rich diversity of life.</p><p>The mechanism of the carbon cycle operates on the basis that the</p><p>carbon locked in plants and animals is gradually released into the</p><p>atmosphere after they die and decompose. This atmospheric carbon is</p><p>then taken up by plants which convert carbon dioxide (CO2) into stems,</p><p>trunks, leaves, etc. through photosynthesis. The carbon then enters the</p><p>food chain as the plants are eaten by animals.</p><p>There is also a geochemical component to the cycle mainly</p><p>consisting of deep ocean water and rocks. The former is estimated to</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 1</p><p>contain 36 billion tonnes and the latter 75 million billion tonnes of</p><p>carbon. Volcanic eruptions and the weathering of rocks release this</p><p>carbon at a relatively slow rate.</p><p>Under natural conditions the release of carbon into the atmos-</p><p>phere is balanced by the absorption of CO2 by plants. The system is in</p><p>equilibrium, or would be if it were not for human interference.</p><p>The main human activity responsible for overturning the balance of</p><p>the carbon cycle is the burning of fossil fuels which adds a further 6 billion</p><p>tonnes of carbon to the atmosphere over and above the natural flux each</p><p>year. In addition, when forests are converted to cropland the carbon in</p><p>the vegetation is oxidised through burning and decomposition. Soil</p><p>cultivation and erosion add further carbon dioxide to the atmosphere.</p><p>If fossil fuels are burnt and vegetation continues to be destroyed at</p><p>the present rate, the CO2 in the atmosphere will treble by 2100. Even if</p><p>there is decisive action on a global scale to reduce carbon emissions,</p><p>atmospheric concentrations will still double by this date.</p><p>With the present fuel mix, every kilowatt hour of electricity used in</p><p>the UK releases one kilogram of CO2. The burning of one hectare of</p><p>forest gives off between 300 and 700 tonnes of CO2.</p><p>These are some of the factors which account for the serious imbal-</p><p>ance within the carbon cycle which is forcing the pace of the green-</p><p>house effect which, in turn, is pushing up global temperatures.</p><p>The greenhouse effect</p><p>A variety of gases collaborate to form a canopy over the Earth which</p><p>causes some solar radiation to be reflected back from the atmosphere,</p><p>thus warming the Earth’s surface, hence the greenhouse analogy. The</p><p>greenhouse effect is caused by long-wave radiation being reflected by</p><p>the Earth back into the atmosphere and then reflected back by trace</p><p>gases in the cooler upper atmosphere, thus causing additional</p><p>warming of the Earth’s surface (Figure 1.1).</p><p>The main greenhouse gases are water vapour, carbon dioxide,</p><p>methane, nitrous oxide and tropospheric ozone (the troposphere is the</p><p>lowest 10–15 kilometres of the atmosphere).</p><p>The sun provides the energy which drives weather and climate. Of</p><p>the solar radiation which reaches the Earth, one third is reflected back</p><p>into space and the remainder is absorbed by the land, biota, oceans,</p><p>ice caps and the atmosphere. Under natural conditions the solar energy</p><p>absorbed by these features is balanced by outgoing radiation from the</p><p>Earth and atmosphere. This terrestrial radiation in the form of long-</p><p>wave, infra-red energy is determined by the temperature of the Earth-</p><p>atmosphere system. The balance between radiation and absorption</p><p>can change due to natural causes such as the 11-year solar cycle.</p><p>Without the greenhouse shield the Earth would be 33�C cooler, with</p><p>obvious consequences for life on the planet.</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>2</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 2</p><p>Since the industrial revolution, the combustion of fossil fuels and</p><p>deforestation has resulted in an increase of 26 per cent in carbon</p><p>dioxide concentrations in the atmosphere. In addition, rising popula-</p><p>tion in the less developed countries has led to a doubling of methane</p><p>emissions from rice fields, cattle and the burning of biomass. Methane</p><p>is a much more powerful greenhouse gas than carbon dioxide. Nitrous</p><p>oxide emissions have increased by 8 per cent since pre-industrial times</p><p>(IPCC 1992).</p><p>Climate change – the paleoclimate record</p><p>In June 1990 scientists were brought up sharp by a graph which</p><p>appeared in the journal Nature (Figure 1.2). It was evidence from ice</p><p>core samples which showed a remarkably close correlation between</p><p>temperature and concentrations of CO2 in the atmosphere from</p><p>160 000 years ago until 1989. It also revealed that present concentra-</p><p>tions of CO2 are higher than at any time over that period. Since then the</p><p>rate of increase has, at the very least, been maintained.</p><p>Ice core samples give information in four ways. First, their melt</p><p>layers provide an indication of the time span covered by the core.</p><p>Second, a measurement of the extent to which ice melted and refroze</p><p>after a given summer gives a picture of the relative warmth of that sum-</p><p>mer. A third indicator is the heavy oxygen isotope 18O in air trapped in</p><p>the ice. It is more abundant in warm years. Finally, the air trapped in the</p><p>snow layers gives a measurement of the CO2 in the atmosphere in a</p><p>Figure 1.1</p><p>The greenhouse ‘blanket’</p><p>CLIMATE CHANGE – NATURE OR HUMAN NATURE?</p><p>3</p><p>Earth’s surface</p><p>a year</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 3</p><p>given year. Other data from ice cores show that, at the peak of the last</p><p>ice age 20 000 years ago, sea level was about 150 m lower than today.</p><p>Another source of what is called ‘proxy’ evidence comes from</p><p>analysing tree rings. This can give a snapshot of climate going back 6000</p><p>years. Each tree ring records one year of growth and the size of each ring</p><p>offers a reliable indication of that year’s climate. The thicker the ring, the</p><p>more favourable the climate to growth. In northern latitudes warmth is</p><p>the decisive factor. Some of the best data come from within the Arctic</p><p>Circle where pine logs provide a 6000-year record.</p><p>The Climate Research Unit of the University of East Anglia has made</p><p>a special study of the evidence for climate changes from different sources</p><p>and has concluded that there is a close affinity between ice core evi-</p><p>dence and that obtained from tree rings. Also instrumental records going</p><p>back to the sixteenth century are consistent with the proxy evidence.</p><p>Causes of climate fluctuation</p><p>To be able to see the current changes in climate in context, it will be</p><p>necessary to consider the causes of dramatic changes in the past.</p><p>A major cause of climate fluctuation has been the variation in the</p><p>Earth’s axial tilt and the path of its orbit round the sun. The Earth is</p><p>subject to the influence of neighbouring planets. Their orbits produce</p><p>a fluctuating gravitational pull on the Earth, affecting the angle of its</p><p>Figure 1.2</p><p>Correspondence between historic</p><p>temperature and carbon dioxide</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>4</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 4</p><p>axis. As the Earth wobbles, vast ice sheets wax and wane over a cycle</p><p>called a Milankovitch cycle. However, thanks to the stabilising pull of</p><p>the moon, the variation in tilt is contained within limits which preserves</p><p>the integrity of the seasons. Without the moon, the axis could move to</p><p>90 degrees from the vertical meaning that half the</p><p>making the</p><p>choice of fuel.</p><p>● High efficiency heating systems should be installed, for example</p><p>condensing boilers, and space heating and hot water systems should</p><p>be appropriately sized.</p><p>● In wet central heating systems thermostatic radiator valves are</p><p>essential.</p><p>● Controls, programmers, and thermostats should be appropriate to</p><p>the task and correctly positioned and their operation easily under-</p><p>stood by occupants.</p><p>● The heating system should be geared to the thermal response of</p><p>the building fabric and occupancy pattern of the dwelling.</p><p>● Hot water storage cisterns and the distribution system should be</p><p>effectively insulated.</p><p>● Where there is a high standard of air tightness a heat recovery ven-</p><p>tilation system is essential.</p><p>● Ventilation of utility areas, bathrooms and kitchens is especially</p><p>desirable to prevent condensation.</p><p>● The venting of hot air in summer should be considered.</p><p>● The environmental benefits of conservatories are cancelled out if</p><p>they are centrally heated.</p><p>Also linked to evolving climate change will be the need to take account</p><p>of increased wind speeds, extremes of climate, heat episodes leading to</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 106</p><p>ADVANCED AND ULTRA-LOW ENERGY HOUSES</p><p>107</p><p>the drying out of ground at normal foundation level. A guide to revised</p><p>building practices has been published as part of the government’s</p><p>advice as to how business can respond to climate change. It includes</p><p>such points as:</p><p>● deeper foundations to cope with ground shrinkage;</p><p>● more robust walls and roofs to withstand intense storms;</p><p>● orientation to present shorter elevation to prevailing winds;</p><p>● Consider more aerodynamic forms (e.g. Swiss Re, p. 158–159).</p><p>(DEFRA 2004.)</p><p>To conclude this chapter it is worth summarising points from an Arup</p><p>report of Autumn 2004 on the likely impact of climate change on UK</p><p>buildings.</p><p>Report by Arup Research and Development</p><p>for the DTI’s Partners in Innovation</p><p>Programme 2004</p><p>Points raised in the report relevant to housing</p><p>Housing built to 2002 Building Regulations will be uncomfortably warm</p><p>to live in by 2020. By 2080 internal temperatures could reach 40�C. It</p><p>suggests that air conditioning and mechanical ventilation will be nec-</p><p>essary, adding that the air conditioning should be driven by PVs or other</p><p>renewable energy sources. Natural ventilation will be counterproductive</p><p>when outside temperature exceeds internal temperature.</p><p>It recommends masonry buildings with high thermal mass over</p><p>timber frame lightweight construction. Smaller windows with shutters</p><p>are recommended. On south facing elevations solar blinds will be</p><p>essential. Where buildings are deficient in thermal mass a possible</p><p>solution is to apply a phase change material to internal surfaces. These</p><p>are now becoming available in plaster form (see p. 137).</p><p>There is a conflict here with the principle of optimising passive</p><p>solar energy. The answer could be removable or sliding heat reflective</p><p>panels which reduce the glazed area in summer. Fitting louvres or exter-</p><p>nal shutters to windows or internal blinds is recommended.</p><p>Arup concludes that by 2080 London will have the climate of the</p><p>Mediterranean coast and we should consider adopting similar building</p><p>techniques to that region.</p><p>AIAC-Ch08.qxd 03/25/2005 17:17 Page 107</p><p>108</p><p>Chapter</p><p>Nine</p><p>Harvesting wind and water</p><p>This chapter is concerned with wind generation which can operate as</p><p>embedded generation in buildings down to the scale of the individual</p><p>house and the conservation of water as the pressure on this resource</p><p>increases.</p><p>Small wind turbines</p><p>In this context ‘small’ means wind machines that are scaled from a few</p><p>watts to 20 kW. Machines between 1 and 5 kW may be used to provide</p><p>either direct current (DC) or alternating current (AC). They are mainly</p><p>confined to the domestic level and are often used to charge batteries.</p><p>The larger machines are suitable for commercial/industrial buildings</p><p>and groups of houses.</p><p>Small-scale electricity production on site has economic disadvant-</p><p>ages in the UK given the present buy-in rates for small operators.</p><p>Currently the government is considering how to redress this inequity and</p><p>thereby give a substantial boost to the market for small-scale renew-</p><p>ables. Wind generation will do well if this happens since it is much less</p><p>expensive in terms of installed cost per kilowatt than PV which makes it</p><p>an attractive proposition as a building integrated power source.</p><p>Wind patterns in the built environment are complex as the air</p><p>passes over, around and between buildings. Accordingly a wind gener-</p><p>ator introduced into this environment must be able to cope with high</p><p>turbulence caused by buildings. Such conditions tend to favour vertical</p><p>axis machines as opposed to the horizontal versions which have prolif-</p><p>erated in wind farms. This is because the vertical versions may be able</p><p>to operate at lower wind speeds and they are less stressed mechani-</p><p>cally by turbulence. In addition, horizontal axis machines mounted on</p><p>roofs tend to transmit vibrations through the structure of the buildings.</p><p>Because of the bending moment produced by the tower under wind</p><p>load, measures must be taken to provide adequate strength in the</p><p>building structure. This may not easily be achieved in retrofit situations.</p><p>By their very nature the vertical axis machines are not affected by</p><p>changes in wind direction or turbulence. They can be sited on roofs or</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 108</p><p>HARVESTING WIND AND WATER</p><p>109</p><p>walls. They have been particularly successful mounted on the sides of</p><p>oil platforms in the North Sea (Figure 9.1).</p><p>The machines are well balanced, transmitting minimum vibration</p><p>and bending stress to walls or roofs. They also have a high output</p><p>power to weight ratio. A further advantage is that the electricity gener-</p><p>ator can be located beneath the rotors and therefore can be located</p><p>within the envelope of the building.</p><p>Wind generation can be complemented by PVs as illustrated</p><p>below (p. 114) by the system patented by Altechnica. The wind gen-</p><p>erators continue operating at night when PVs are in retirement (see</p><p>Figure 9.9).</p><p>A prediction in ‘WIND Directions’, March 2001, estimates that the</p><p>global market for small turbines by 2005 will be around Euros 173 million</p><p>and several hundreds of million by 2010. For example, in the Netherlands</p><p>alone there is the potential for 20 000 urban turbines to be installed on</p><p>industrial and commercial buildings by 2011.</p><p>The increasing deregulation of the energy market creates an</p><p>increasingly attractive proposition for independent off-grid small-scale</p><p>generation insulating the operator from price fluctuations and reliabil-</p><p>ity uncertainties, with the proviso that there is a level playing field.</p><p>Currently there are several versions of vertical axis machines on the</p><p>market. However, they are still undergoing development. When it is</p><p>fully appreciated that these machines are reliable, silent, low mainte-</p><p>nance, easy to install and competitive on price, it is likely the market will</p><p>expand rapidly. At present the regulatory regime for small turbines is</p><p>much less onerous than for �20 kW machines. It is to be hoped that the</p><p>bureaucrats fail to spot this red tape opportunity.</p><p>Research conducted by Delft University of Technology and Ecofys</p><p>identified five building conditions to determine their effectiveness for</p><p>wind turbines. They are described as ‘wind catchers’, ‘wind collectors’,</p><p>‘wind sharers’ and ‘wind gatherers’, terms which define their effect on</p><p>wind speed. The wind catcher is well suited to small turbines being usu-</p><p>ally high and benefiting from a relatively free wind flow. Small horizon-</p><p>tal axis machines could be satisfactory in this situation.</p><p>The wind collector type of building has a lower profile and can be</p><p>subject to turbulence. This is where the vertical axis machine comes</p><p>into its own. The third type, wind sharers, are found in industrial areas</p><p>and business parks. Their relatively even roof height and spaced out sit-</p><p>ing makes such buildings subject to high winds and turbulence. Ecofys</p><p>has produced a diagram which depicts how four urban situations cope</p><p>with varying wind conditions. There is a fifth category, the ‘winddreamer’</p><p>which relates to low rise developments (Figure 9.2).</p><p>Development work is continuing on designs for turbines which are</p><p>suitable for the difficult wind conditions found in urban situations. This</p><p>is appropriate since climate change predictions indicate that wind</p><p>speeds will increase as the atmosphere heats up and so becomes more</p><p>dynamic. There is growing confidence that there will be a large market</p><p>Figure 9.1</p><p>Helical side mounted turbine on oil</p><p>platform</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 109</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>110</p><p>for mini-turbines in various configurations on offices, housing blocks</p><p>and individual dwelling.</p><p>Types of small-scale wind turbine</p><p>Most small systems have a direct drive permanent magnet generator</p><p>which limits mechanical transmission losses. Systems under 2 kW usu-</p><p>ally have a 24–48 volt capacity aimed at battery charging or a DC circuit</p><p>rather than having grid compatibility.</p><p>Up to the present, horizontal axis machines are much more in evi-</p><p>dence that the vertical axis type even at this scale. These machines have</p><p>efficient braking systems for when wind speed is excessive. Some even</p><p>tip backwards in high winds adopting the so-called ‘helicopter posi-</p><p>tion’. There are advantages to horizontal axis machines such as:</p><p>● the cost benefit due to economy of scale of production;</p><p>● it is a robust and tested technology;</p><p>● automatic start-up;</p><p>● high output.</p><p>The disadvantages are:</p><p>● the necessity of a high mast;</p><p>● mounted on buildings they require substantial foundation support;</p><p>Figure 9.2</p><p>Categories of building cluster and their</p><p>effectiveness for wind generation</p><p>(courtesy of Ecofys and REW)</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 110</p><p>HARVESTING WIND AND WATER</p><p>111</p><p>● in urban situations where there can be large variations in wind</p><p>direction and speed, this necessitates frequent changes of orientation</p><p>and blade speed. This not only undermines power output, it also</p><p>increases the dynamic loading on the machine with consequent</p><p>wear and tear;</p><p>● there are noise problems with this kind of machine especially asso-</p><p>ciated with braking in high winds;</p><p>● they can be visually intrusive.</p><p>As stated earlier, vertical axis turbines are particularly suited to urban sit-</p><p>uations and to being integrated into buildings. They are discrete and vir-</p><p>tually silent and much less likely to trigger the wrath of planning officials.</p><p>The most common vertical axis machine is the helical turbine as</p><p>seen at Earth Centre, Doncaster (Figure 9.3). In that instance it is mounted</p><p>on a tower but it can also be side-hung on a building.</p><p>Another variety is the S-Rotor which has an S-shaped blade</p><p>(Figure 9.4).</p><p>The Darrieus-Rotor employs three slender elliptical blades which</p><p>can be assisted by a wind deflector. This is an elegant machine which</p><p>nevertheless needs start-up assistance (Figure 9.4).</p><p>A variation of the genre is the H-Darrieus-Rotor with triple vertical</p><p>blades extending from the central axis (Figure 9.4).</p><p>Yet another configuration is the Lange turbine which has three sail-</p><p>like wind scoops (Figure 9.4).</p><p>Last in this group is the ‘Spiral Flugel’ turbine in which twin blades</p><p>create, as the name indicates, a spiral profile (Figure 9.5).</p><p>Produced by Renewable Devices Ltd, the Swift wind turbine claims</p><p>to be the world’s first silent rooftop mounted wind turbine (35 dB) by</p><p>incorporating silent aerodynamic rotor technology coupled with a rev-</p><p>olutionary electronic control system. Care has been taken to provide a</p><p>secure mounting system which will not transfer vibrations. Its peak out-</p><p>put is 1.5 kW and it is estimated that avoided fossil fuel generation pro-</p><p>duces a saving of 1.8 tonnes per year of carbon dioxide (CO2). The first</p><p>unit was installed in Collydean Primary School, Glenrothes, Scotland,</p><p>and there are plans for installations in four other primary schools. It is</p><p>regarded as an ideal system for residential developments (Figure 9.6).</p><p>A development from the 1970s has placed the turbine blades</p><p>inside an aerofoil cowling. A prototype developed at the University of</p><p>Rijeka, Croatia, claims that this combination can produce electricity</p><p>60 per cent more of the time compared with conventional machines.</p><p>This is because the aerofoil concentrator enables the machines to</p><p>produce electricity at slower wind speeds than is possible with conven-</p><p>tional turbines.</p><p>The cross-section of the cowling has a profile similar to the wing of</p><p>an aircraft which creates an area of low pressure inside the cowling. This</p><p>has the effect of accelerating the air over the turbine blades. As a result,</p><p>more electricity is produced for a given wind speed as well as generating</p><p>Figure 9.3</p><p>Helican turbine on a column at Earth</p><p>Centre, Doncaster</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 111</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>112</p><p>at low air speeds compared to a conventional rotor. This amplification</p><p>of wind speed has its hazards, for example blades can be damaged.</p><p>The answer has been to introduce hydraulically driven air release vents</p><p>into the cowling which are activated when the pressure within the cowl-</p><p>ing is too great. They also serve to stabilise electricity output in turbu-</p><p>lent wind conditions, which makes them appropriate for urban sites.</p><p>This technology can generate power from 1 kW to megawatt</p><p>capacity. It is being considered for offshore application. The device</p><p>is about 75 per cent more expensive than conventional rotors but the</p><p>efficiency of performance is improved by a factor of five as against a</p><p>conventional horizontal axis turbine (Figures 9.7 and 9.8).</p><p>A mini horizontal axis turbine was introduced in late 2003 called</p><p>the Windsave. It can generate up to 750 watts at an installed cost of</p><p>£1 per watt. Its manufacturers claim it could meet about 15 per cent of</p><p>Figure 9.4</p><p>Left: S-Rotor; top centre: Darrieus-</p><p>Rotor; bottom centre: Lange turbine;</p><p>right: H-Darrieus-Rotor</p><p>Figure 9.5</p><p>Spiral Flugel rotor</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 112</p><p>HARVESTING WIND AND WATER</p><p>113</p><p>Figure 9.8</p><p>Simulation of wind turbines on the Vivo shopping complex, Hamburg</p><p>Figure 9.7</p><p>Wind turbine with cowling wind</p><p>concentrator</p><p>Figure 9.6</p><p>Swift rooftop wind energy system</p><p>the average household electricity demand. It starts generating at a</p><p>wind speed as low as 3 mph but is most efficient at 20 mph. Producing</p><p>AC power it can be linked directly to the grid and the householder</p><p>credited under the Renewables Obligation charges which currently pay</p><p>a green electricity provider 6 p per kilowatt hour. By using remote</p><p>metering, each unit can be telephoned automatically each quarter to</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 113</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>114</p><p>assess the amount of electricity generated. The power company then</p><p>collects the subsidy and distributes it back to the home owner on the</p><p>basis of the total generated. It is this subsidy which justifies a claim that</p><p>the payback time can be as short as 30 months (Figure 9.9).</p><p>Building integrated systems</p><p>The Vivo building illustrates one version of a building integrated wind</p><p>generating system. There is increasing interest in the way that the</p><p>design of buildings can incorporate renewable technologies including</p><p>wind turbines. Up to now such machines have been regarded as</p><p>adjunct to buildings but a concept patented by Altechnica of Milton</p><p>Keynes demonstrates how multiple turbines can become a feature of</p><p>the design.</p><p>The system is designed to be mounted on the ridge of a roof or at</p><p>the apex of a curved roof section. Rotors are incorporated in a cage-like</p><p>structure which is capped with an aerofoil wind concentrator called in</p><p>this case a ‘Solairfoil’. The flat top of the Solairfoil can accommodate</p><p>PVs. Where the rotors are mounted at the apex of a curved roof the</p><p>effect is to concentrate the wind in a manner similar to the Croatian</p><p>cowling (Figure 9.10).</p><p>The advantage of this system is that it does not become an over-</p><p>assertive visual feature</p><p>and is perceived as an integral design element.</p><p>It is also a system which can easily be fitted to existing buildings where</p><p>the wind regime is appropriate. Furthermore it indicates a building</p><p>which is discretely capturing the elements and working for a living.</p><p>The European Union Extern-E study has sought to put a price on</p><p>the damage inflicted by fossil fuels compared with wind energy. The</p><p>research has concluded that, for 40 GW of wind power installed by</p><p>Figure 9.9</p><p>Windsave rooftop wind energy system</p><p>Altechnica SolAirfoil™</p><p>Patented Altechnica Aeolian Roof™ Wind Energy System</p><p>PV clad roof</p><p>wind turbine shown is</p><p>Altechnica Wheel Darrieus™</p><p>cross flow wind turbine</p><p>Altechnicac</p><p>Figure 9.10</p><p>‘Aeolian’ roof devised by Altechnica</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 114</p><p>HARVESTING WIND AND WATER</p><p>115</p><p>2010, and with a total investment of Euros 24.8 billion up to 2010, CO2</p><p>emissions could be reduced by 54 million tonnes per year in the final</p><p>year. The cumulative saving would amount to 320 million tonnes CO2</p><p>giving avoided external costs of up to Euros 15 billion.</p><p>This is the first sign of a revolution in the way of accounting</p><p>for energy. When the avoided costs of external damage are realistically</p><p>factored in to the cost of fossil fuels, the market should have no diffi-</p><p>culty in switching to renewable energy en masse.</p><p>Conservation of water in housing</p><p>Not only is water a precious resource in its own right, there is also an</p><p>energy component in storing and transporting it and making it drink-</p><p>able. On average a person in the UK uses 135 litres (30 gallons) of water</p><p>per day. Of this total about half is used for flushing toilets and personal</p><p>hygiene. A really thorough home ecological improvement strategy</p><p>should have three components:</p><p>● reduce consumption;</p><p>● harvest rainwater;</p><p>● recycle grey water.</p><p>Reducing consumption</p><p>Flushing toilets use about 30 per cent of total household consumption.</p><p>This can be reduced by changing to a low flush toilet (2–4 litres) or a</p><p>dual flush cistern. Aerating (spray) taps on basins, sinks and on shower</p><p>heads make a big impact on consumption. All appliances should have</p><p>isolating stopcocks so that the whole system does not have to be</p><p>drained off if one item has a problem. Washing machines and dish-</p><p>washers vary in the amount of water they consume. This is one of the</p><p>factors which should influence the choice of white goods.</p><p>On average about 200 litres of rainwater fall on the roof of a 100 m2</p><p>house each day in the UK. In many homes this is collected in water butts</p><p>and used to irrigate the garden. However, it has wider uses. There are</p><p>several proprietary systems for collecting and treating rainwater so that</p><p>it can be used to flush WCs and for clothes washing machines. An</p><p>example is the Vortex water harvesting system which serves roof areas</p><p>up to 200 m2 and 500 m2 respectively. Recycled rainwater must only be</p><p>sourced from roofs. Storage tanks are either concrete or glass</p><p>reinforced plastic (GRP). There are controls to ensure that mains water</p><p>can make good any deficiencies in rainfall. If filtered rainwater is to be</p><p>used for other domestic purposes, other than drinking, it must be sub-</p><p>ject to further purification, usually by ultraviolet light. Best use of the</p><p>filtered rainwater will be made if associated with dual flush WCs.</p><p>Figure 9.11 shows a typical configuration for rainwater storage.</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 115</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>116</p><p>It is possible to go a stage further and use rainwater for drinking,</p><p>but this requires even more rigorous filtration, as employed, for exam-</p><p>ple, in the the Vales’ Southwell autonomous house (p. 77). The water</p><p>from the roof passes through a sand filter in a conservatory. From here</p><p>it is pumped to storage tanks in the loft and from there through a</p><p>ceramic/carbon filter to the taps. As an act of faith in the English</p><p>weather there is no mains backup facility.</p><p>A variation on the water recycling strategy is to reuse grey water</p><p>from wash basins, showers and baths. If waste water from a washing</p><p>machine is included, then virtually all the waste water can be used to</p><p>meet the needs of flushing toilets. Again there are systems on the</p><p>market which serve this function, including water storage.</p><p>The Hockerton Housing Project has all these facilities and more</p><p>because it uses rainwater collected from its conservatory roofs for</p><p>drinking purposes. The water is stored in 25 000 litre underground tanks</p><p>where particles have time to settle to the bottom. The water is treated</p><p>first by passing it through a 5 micron filter to remove remaining particles.</p><p>Then it is sent through a carbon filter to remove dissolved chemicals.</p><p>Lastly it is subjected to ultraviolet light to kill bacteria and viruses. The</p><p>author can vouch for its purity! For the average home this may well be</p><p>a step too far, but those who feel inspired by this possibility should</p><p>contact the Hockerton Housing Project at www.hockerton.demon.co.uk.</p><p>For the really dedicated there is the composting toilet which elimi-</p><p>nates the need for water and drainage. In Europe a popular version is</p><p>7</p><p>9</p><p>4</p><p>2</p><p>1</p><p>8</p><p>1011</p><p>12</p><p>5</p><p>6</p><p>3</p><p>1313</p><p>1 Vortex fine filter</p><p>2 inflow smoothing filter</p><p>3 Tank</p><p>4 Floating fine suction filter</p><p>5 Suction hose</p><p>6 Multigo pressure pump</p><p>7 Pressure hose</p><p>8 Automatic switch and</p><p>ballvalve</p><p>9 Overflow trap</p><p>10 Installation controls</p><p>11 Magnetic valve</p><p>12 Open inflow for drinking</p><p>water feed</p><p>13 Backpressure flaps</p><p>Typical domestic rainwater installation with storage tank</p><p>in the ground and a pressure pump in the tank</p><p>Figure 9.11</p><p>Rainwater storage system layout</p><p>(courtesy of Construction Resources)</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 116</p><p>the Clivus Multrum from Sweden. It is a two-storey appliance in that</p><p>there has to be a composting chamber usually on the floor below the</p><p>toilet basin. Fan-assisted ducted air ensures an odourless aerobic</p><p>decomposition process. The by-product from the composting chamber</p><p>is a rich fertiliser.</p><p>Domestic appliances</p><p>As the building fabric of a home becomes more energy efficient, the</p><p>impact of appliances like white goods and TVs becomes a much more</p><p>significant element of the energy bill. Refrigerators and freezers are</p><p>particular culprits. In 1999 the European Commission decreed that all</p><p>white goods, refrigerators, freezers, washing machines, dishwashers etc.</p><p>should be given an energy efficiency rating from A to G. This has cer-</p><p>tainly been effective in sending E, F and Gs to the bottom of the best</p><p>buys. However, whilst A is the top of the scale there is variation within</p><p>this category which has prompted the introduction of an AA category.</p><p>A surprising amount of electricity demand is due to standby elec-</p><p>trical consumption. Some appliances like televisions and personal com-</p><p>puters have optional standby modes which, nevertheless, are left on</p><p>power because the consumption involved is regarded as insignificant.</p><p>Others, like fax machines and cordless telephones need to be perma-</p><p>nently on standby. Even appliances with electronic clocks consume</p><p>power. It has been estimated that a typical household could consume</p><p>600 kWh per year on standby alone. For the EU it has been calculated</p><p>that standby power accounts for 100 billion kWh/year, about one fifth</p><p>the consumption of a state the size of Germany.</p><p>HARVESTING WIND AND WATER</p><p>117</p><p>AIAC-Ch09.qxd 03/25/2005 17:19 Page 117</p><p>118</p><p>Chapter</p><p>Ten</p><p>Existing housing: a</p><p>challenge and opportunity</p><p>So far the emphasis has been on new buildings, mainly houses, yet</p><p>these comprise only about 2 per cent of the total building stock at any</p><p>one time. If buildings are to contribute to carbon abatement in the</p><p>short to medium term then existing buildings must be targeted.</p><p>Currently there is considerable interest in converting redundant</p><p>industrial buildings to other uses, especially residential. However, the real</p><p>challenge lies in existing housing. In England and Wales housing is</p><p>responsible for about 28 per cent of total carbon dioxide (CO2) emissions.</p><p>The UK government is introducing a requirement</p><p>for houses that</p><p>come on the market to be accompanied by a ‘House Condition Survey’,</p><p>which will include an Energy Efficiency Report. This will not only enable</p><p>purchasers to compare older houses with new build but will also moti-</p><p>vate vendors to upgrade their property in advance of a sale. It is sched-</p><p>uled to come into force in 2006.</p><p>The International Energy Agency, which considers energy efficiency</p><p>worldwide, described UK housing as ‘poorly insulated’ with ‘consider-</p><p>able scope for improvement’. At the same time, government improve-</p><p>ment programmes were ‘unconvincing’ with ‘funding low in proportion</p><p>to the magnitude of the task’. What is the magnitude of the task?</p><p>To gauge the scale of the problem we first need to consider the</p><p>four accredited ways of measuring the energy efficiency of both exist-</p><p>ing and new homes:</p><p>● the SAP method;</p><p>● the NHER profile;</p><p>● the BEPI profile;</p><p>● the carbon dioxide measure.</p><p>The official government system of measurement of energy efficiency is</p><p>the Standard Assessment Procedure (SAP) which comprises a calcula-</p><p>tion of the heat loss resulting from the form of the building, the thermal</p><p>properties of its fabric and the level of ventilation. This information is</p><p>equated with the cost of making good the heat loss by means of the</p><p>heating system and the cost of fuel. It also takes into account benefits</p><p>from solar gain. Its scale is from 1 to 120. New homes complying with</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 118</p><p>EXISTING HOUSING: A CHALLENGE AND OPPORTUNITY</p><p>119</p><p>the Building Regulations according to the SAP method will probably</p><p>have to be a minimum of SAP 100. The unofficial recommended mini-</p><p>mum for reasonable energy efficiency for existing homes is SAP 60.</p><p>The National Home Energy Rating (NHER) uses a scale of 1 to 10,</p><p>and includes such items as the method of space heating, domestic hot</p><p>water, appliances and lighting and is designed to give an indication of</p><p>energy costs. The national average NHER is around 4.0.</p><p>The Building Energy Performance Index (BEPI) assesses the ther-</p><p>mal performance of the fabric of the building taking into account its ori-</p><p>entation. It does not include heating systems and does not factor in the</p><p>cost of energy. The Building Regulations standard equates to a BEPI of</p><p>100. Because this measure is confined to the efficiency of the building</p><p>fabric, this is a more accurate long-term measure of energy efficiency,</p><p>since appliances and heating systems have a relatively short life and</p><p>there is no guarantee that replacements will measure up to the previous</p><p>standard. It is a performance indicator that gives an accurate reading of</p><p>the energy efficiency of the total fabric and cannot be manipulated to</p><p>gain a notional but unreal advantage. Thus it gives an accurate picture</p><p>of the underlying condition of the housing stock.</p><p>The Carbon Dioxide Profile indicates the carbon dioxide emissions</p><p>deriving from the total energy used by a property taking into account</p><p>the type of fuel. For example, for a given unit of heat, electricity has</p><p>roughly four times the carbon intensity of gas. It is measured in</p><p>kg/square metre/year. In the revised Building Regulations 2005, a carbon</p><p>emission standard will be the only route to compliance.</p><p>The English House Condition Survey 1996 found that 84.6 per cent</p><p>of dwellings were at or below SAP 60 with 8 per cent at or below SAP 20.</p><p>The current average for England overall is SAP 43.8. This is gradually</p><p>improving as the ratio of new homes to existing increases. However, in</p><p>the private rented sector in England 21 per cent are at or below SAP 20,</p><p>with 12.8 per cent of this sector being at or below SAP 10. Within</p><p>the �10 category the bottom end is as low as SAP minus 25. To put</p><p>some numbers against these standards, 3.3 million homes in England</p><p>are at or below SAP 30, 1.6 million are at or below SAP 20 and 900 000</p><p>are at or below SAP 10 (English House Condition Survey, DETR 1996,</p><p>December 2000). These numbers are substantially increased when</p><p>Britain as a whole is considered.</p><p>This constitutes a monumental problem which calls for constant</p><p>pressure on governments to rise to the challenge of upgrading the</p><p>housing stock. At present the amount of investment in this area of need</p><p>is totally inadequate and it is being left to enlightened bodies like hous-</p><p>ing associations to take the initiative.</p><p>So, how does this translate into actual home heating habits?</p><p>The official standard for adequate heating in a living room is 21�C</p><p>and in other rooms, 18�C. Only 25 per cent of homes have internal tem-</p><p>peratures which meet these standards. The minimum heating regime is</p><p>18�C for the living room and 16�C for other rooms.</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 119</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>120</p><p>When the external temperature drops to 4�C, then</p><p>● 50 per cent of owner occupied dwellings fail to reach the minimum</p><p>standard;</p><p>● 62 per cent of council homes; and</p><p>● 95 per cent of the private rented sector also fail to meet the mini-</p><p>mum standard.</p><p>These figures are from the DETR House Condition Survey for England.</p><p>Many of the owner occupied homes are of 1930s vintage. How do</p><p>they compare with today’s best practice? One crucial measure is carbon</p><p>dioxide emissions. To achieve adequate space heating a 1930s house is</p><p>responsible for 4.7 tonnes of carbon dioxide. This compares with</p><p>0.6 tonnes in current best practice homes. A 1976 house which was the</p><p>first to encounter thermal regulations will account for 2.6 tonnes of CO2</p><p>for space heating. Taking into account all fittings and appliances as well</p><p>as the building fabric, a superinsulated house with best available tech-</p><p>nology will produce a total of 2 tonnes of CO2 as against 8 tonnes in</p><p>total for a 1930s dwelling.</p><p>There is a strong social dimension to this state of affairs.</p><p>The UK government acknowledges that up to 3 million households in</p><p>England are officially designated ‘fuel poor’. The definition is that they are</p><p>unable to obtain adequate energy services for 10 per cent of their income.</p><p>Most of those energy services are of course taken up with space heating.</p><p>We have the worst record in the EU for extra winter deaths. In the winter</p><p>of 1999–2000 almost 55 000 died from cold related illnesses between</p><p>December and March as against the other two four monthly periods. This</p><p>was the highest winter total since 1976 yet it was a relatively mild winter. In</p><p>addition there was steep rise in the rate of respiratory and cardiovascular</p><p>illnesses. About half of this total can be attributed to poor housing.</p><p>The main culprit is cold, poorly insulated and damp homes as</p><p>acknowledged by the government in its document Fuel Poverty: The</p><p>New HEES (DETR 1999):</p><p>The principal effects of fuel poverty are health related, with</p><p>children, the old, the sick and the disabled most at risk. Cold</p><p>homes are thought to exacerbate existing illnesses such as</p><p>asthma and reduced resistance to infections.</p><p>Dr Brenda Boardman of Oxford University’s Environmental Change</p><p>Institute has estimated that well over £1 billion per year is spent by the</p><p>National Health Service on illnesses directly attributable to cold and</p><p>damp homes. This figure may be significantly higher in that it is impos-</p><p>sible to quantify the contribution of poor housing to depressive ill-</p><p>nesses. The DTER acknowledges that fuel poor households</p><p>also suffer from opportunity loss, caused by having to use a</p><p>larger portion of income to keep warm than other households.</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 120</p><p>EXISTING HOUSING: A CHALLENGE AND OPPORTUNITY</p><p>121</p><p>This has adverse effects on the social well-being and overall</p><p>quality of life for both individuals and communities.</p><p>(Fuel Poverty: The New HEES, op. cit.)</p><p>This cost will taper off as the upgrading programme gathers</p><p>momentum.</p><p>A book appeared in 2000 called Cutting the Cost of Cold (ed.</p><p>Rudge and Nicol, Spon) which should remove any doubts there may</p><p>be about the linkage between poor housing and ill health. Increasingly</p><p>damp as well as cold is emerging as a major health hazard. Damp gen-</p><p>erates mould and mould spores</p><p>can trigger allergies and asthma</p><p>attacks. Some moulds are toxic, as in the genus Penicillium which can</p><p>damage lung cells. It was confidence in the connection between damp</p><p>homes and asthma that justified the Cornwall and Isles of Scilly Health</p><p>Authority in directing £300 000 via district councils to thermally</p><p>improve homes of young asthma patients. This was undertaken as</p><p>much as an investment opportunity as a remediation intervention. The</p><p>outcome was that the savings to the NHS exceeded the annual equiv-</p><p>alent cost of the house improvements. The report on this enterprise,</p><p>sponsored by the EAGA Trust, states: ‘This study provides the first</p><p>evaluation of health outcomes following housing improvements’. It will</p><p>surely be the first of many since it provides hard evidence of cost effec-</p><p>tiveness. At the opposite end of the country, almost a quarter of all</p><p>homes suffer from damp in Scotland (National Housing Agency for</p><p>Scotland).</p><p>The connection between housing and health has been recognised</p><p>by the medical profession in a report Housing and Health: Building for</p><p>the Future (eds Sir David Carter and Samantha Sharp, British Medical</p><p>Association 2003). This is a thorough analysis of the situation from the</p><p>medical standpoint.</p><p>The remedy</p><p>There is no easy way to solve this problem and considerable investment</p><p>will be required by central government if fuel poverty linked to sub-</p><p>standard housing is to be eliminated. An example of a retrofit package</p><p>for housing would consist of:</p><p>● improving the level of insulation in walls and roof and, where possi-</p><p>ble, floor;</p><p>● draught-proofing;</p><p>● installing Low E double glazing preferably in timber frames;</p><p>● installing/converting central heating to include a gas condensing</p><p>boiler;</p><p>● installing heat recovery ventilation system.</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 121</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>122</p><p>From the architectural point of view the insulation is the main challenge.</p><p>It can take three forms:</p><p>● external overcladding (enveloping);</p><p>● filling the cavity;</p><p>● internal dry lining.</p><p>Case study</p><p>Penwith Housing Association in Penzance, Cornwall, was formed in</p><p>1994 to take over the local authority housing from Penwith District</p><p>Council to make it possible to gain access for funds to upgrade the</p><p>entire stock. This consisted of a mix of 1940s houses with solid concrete</p><p>block walls and post-war cavity built homes. The 1940s examples had a</p><p>SAP rating of 1 and an NHER of 1.1. The application of external insula-</p><p>tion, additional roof insulation and double glazing raised this to SAP 26.</p><p>However, the crucial BEPI rating was raised to 97, i.e. close to Building</p><p>Regulations standard current at the time. The addition of gas central</p><p>heating raised the SAP to 76 which dramatically illustrates the effect of</p><p>fixed appliances to the SAP value.</p><p>Being of concrete construction and rendered there was no problem</p><p>as regards changing the appearance by overcladding. The technique</p><p>involves applying a render to provide an even and smooth fixing surface</p><p>to the rigid insulation panels. The panels then receive a waterproofing</p><p>finish. A mesh is applied to the insulation to provide a key for the exter-</p><p>nal waterproof render which is finished with pebble dash (Figure 10.1).</p><p>External cladding has a number of consequences. For example,</p><p>carrying it round window reveals means that the window frame size is</p><p>reduced. Roof eaves and verges have to be extended and rainwater/soil</p><p>vent pipes have to be modified to take account of the deeper eaves.</p><p>It is necessary for the insulation boards to receive a finishing coat.</p><p>In the case of most insulants the finish should offer total waterproofing.</p><p>A polymer-based render is the most reliable in this respect. This is an</p><p>adhesive render with an alkali resistant glass fibre mesh as reinforcement.</p><p>Applied in one or two coats it offers a choice of finishes, for example:</p><p>● pebble dash or spar dash;</p><p>● textured renders in a range of colours;</p><p>● roughcast, also called harling or wet cast.</p><p>It is also possible to use cladding which includes</p><p>● lightweight natural stone aggregate;</p><p>● brick;</p><p>● tile, e.g. terracotta;</p><p>● weatherboarding.</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 122</p><p>EXISTING HOUSING: A CHALLENGE AND OPPORTUNITY</p><p>123</p><p>Figure 10.1</p><p>Social housing with cladding over solid</p><p>wall construction, Penzance</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 123</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>124</p><p>Benefits</p><p>● There is a significant improvement in comfort levels throughout the</p><p>whole house.</p><p>● The walls of the building are protected from weathering, ensuring a</p><p>longer life.</p><p>● There should be absolute protection from penetration by damp.</p><p>● The incidence of condensation is reduced to near zero.</p><p>● It allows the fabric of the home to act as a heat store – a warmth</p><p>accumulator.</p><p>● It stabilises the structure, preventing cracking due to differential</p><p>thermal expansion.</p><p>● Space heating bills can be reduced by up to 50 per cent.</p><p>● The increase in property value as a result of the upgrading usually</p><p>more than offsets the cost.</p><p>● There is normally a significant improvement in appearance.</p><p>● The operation can be undertaken without the need to vacate the</p><p>property.</p><p>● There is a significant reduction in carbon dioxide emissions.</p><p>Government estimates suggest that, over the lifetime of the build-</p><p>ing, one tonne of CO2 is saved for every square metre of 50 mm</p><p>thick insulation.</p><p>An example of an individual house application of external cladding is</p><p>Baggy House in the UK which illustrates the ‘Dryvit’ system called</p><p>‘Outsulation’ (Figure 10.2).</p><p>Where there are overriding reasons for not wishing to overclad</p><p>with insulation, as, for example, in the case of eighteenth to nineteenth</p><p>century terraced housing, the alternative is to fix insulation to the inside</p><p>face of external walls – ‘dry lining’. The dilemma is that this reduces</p><p>internal space. To bring a 140 mm solid external wall near to the current</p><p>Figure 10.2</p><p>Baggy House, Devon</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 124</p><p>Buildings Regulations standard would require at least 90 mm of insulation</p><p>with a plasterboard finish. A suitable insulant is cellular glass fixed to</p><p>the wall mechanically. The finish is either plasterboard with a skim coat</p><p>of plaster or plaster applied to metal lathing. There are consequences</p><p>to using this system, such as the relocation of skirtings and electrical</p><p>sockets and the reduced size of door and window openings. There is</p><p>also the risk of cold bridging if the insulation is not continued around</p><p>the reveals to openings. This could involve the replacement of external</p><p>doors and windows. However, this is one instance where the best can</p><p>be the enemy of the good and compromise is reasonable.</p><p>Cavity filling</p><p>Where there are cavity walls injecting insulation through holes drilled at</p><p>regular intervals is a common practice. However, caution should be</p><p>exercised regarding the kind of insulation selected and the bona fides</p><p>of the installation contractor. Post-completion inspections have discov-</p><p>ered a number of cases of fraud where only a notional amount of insu-</p><p>lation has been injected. Properly installed cavity filled insulation can</p><p>have a significant impact on the thermal performance. In the Penwith</p><p>1960s properties, following cavity filling and extra roof insulation the</p><p>BEPI was 107 with a SAP of 49. Where central heating was installed the</p><p>SAP rose to 78 again illustrating why the BEPI is a more useful guide to</p><p>the long-term energy efficiency of a house since it focuses on the fabric.</p><p>Some of the least energy efficient dwellings exist in multi-storey</p><p>buildings, the most notorious being tower blocks. The team responsi-</p><p>ble for the innovative Integer House has been commissioned by</p><p>Westminster Council to raise the energy efficiency of one of its</p><p>20 storey tower blocks as a demonstration of best practice in renova-</p><p>tion. This will be one to watch. (For further information refer to Smith,</p><p>P.F. (2004) Eco-Refurbishment: A Guide to Saving and Producing Energy</p><p>in the Home, Architectural Press.)</p><p>The Roundwood Estate in Brent is typical</p><p>of many former council</p><p>developments with its numerous four storey flats and maisonettes</p><p>linked by balcony access. The 564 dwellings have been transferred to</p><p>the Fortunegate Housing Association. They have solid one and a half</p><p>brick solid external walls and minimal insulation in the roofs. After con-</p><p>sultation with the tenants PRP Architects agreed a specification includ-</p><p>ing overcladding external walls with an insulated render system,</p><p>increased roof insulation, full central heating with combination boilers,</p><p>and new kitchens and bathrooms with extractor fans. Existing double</p><p>glazing was considered adequate. The result is that on average each</p><p>flat will save 1.5 tonnes of CO2 emissions per year with a reduced fuel</p><p>bill of £150 per year. At the same time comfort levels have substantially</p><p>improved.</p><p>This is the kind of unromantic but challenging work which will have</p><p>to be undertaken nationwide if the consequences of fuel poverty are to</p><p>EXISTING HOUSING: A CHALLENGE AND OPPORTUNITY</p><p>125</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 125</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>126</p><p>be overcome. An example of a considerable quantity of former council</p><p>stock is the balcony access flats in the Roundwood estate. Refurbishment</p><p>and overcladding is under way on this estate (Figure 10.3).</p><p>As a postscript to this chapter it should be noted that existing</p><p>homes that are substantially refurbished are likely to need to comply</p><p>with Part L of the Buildings Regulations. As mentioned earlier, Part L is</p><p>being revised and this will have the aim of achieving a 25 per cent</p><p>improvement in energy efficiency. At the same time, the sole criterion</p><p>for compliance will be based on carbon emissions which will close the</p><p>loophole of the trade-offs, so much abused in the past. Another change</p><p>is that houses will be subject to air tightness standards and will have to</p><p>submit to pressure testing.</p><p>From January 2007 it is likely that houses for sale will require a</p><p>Home Condition Report. This will include an Energy Survey. For new</p><p>homes there are currently discussions about enhancing the energy effi-</p><p>ciency scale to take account of zero carbon homes.</p><p>Figure 10.3</p><p>Roundwood Estate Housing</p><p>Association flats, existing and</p><p>refurbished</p><p>AIAC-Ch10.qxd 03/25/2005 17:20 Page 126</p><p>127</p><p>Chapter</p><p>Eleven</p><p>127</p><p>Low energy techniques for</p><p>non-domestic buildings</p><p>Design principles</p><p>Offices in particular have traditionally been extravagant users of energy</p><p>because, in relation to all other costs, energy is a relatively minor frac-</p><p>tion of the total annual budget. In many cases the major electricity cost</p><p>is incurred by lighting. The 1980s sealed glass box may use energy at</p><p>a rate of over 500 kWh/m2/year. Currently, best practice is in the region</p><p>of 90 kWh/m2/year. The aim of the architect under the sustainability</p><p>banner is to maximise comfort for the inhabitants whilst minimising,</p><p>ultimately eliminating, reliance on fossil-based energy.</p><p>The Movement for Innovation (M4I) has produced six performance</p><p>indicators as conditions for sustainable design. They are designed to</p><p>validate or otherwise claims that buildings are ‘green’.</p><p>1. Operational energy</p><p>The energy consumed by a commercial building during its lifetime</p><p>should be kept to a minimum. The benchmark is currently 100 kWh/m2</p><p>but this will become more stringent as pressure mounts to limit carbon</p><p>emissions. Techniques such as high insulation, thermal mass, passive</p><p>and active solar optimisation, natural light, natural ventilation, on-site</p><p>electricity generation and seasonal energy storage are components of</p><p>the green agenda.</p><p>2. Embodied energy</p><p>Minimising the carbon content of materials in the extraction, manufac-</p><p>ture, delivery and construction stages. Promoting the use of recycled</p><p>materials and designing for reuse after demolition.</p><p>3. Transport energy</p><p>Avoiding unnecessary transport journeys during construction in terms</p><p>of the delivery of materials and the removal of site waste. In some</p><p>cases, like the Wessex Water offices near Bath (see first edition) staff are</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 127</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>128</p><p>obliged to use communal transport wherever possible. There is also the</p><p>matter of location even though this will usually be outside the province</p><p>of the architect. Access to good public transport should be a prime</p><p>requisite in deciding location. There have been instances where corpo-</p><p>rations have relocated from city centres accessible only by public trans-</p><p>port to highly energy efficient offices on out of town sites. This has</p><p>encouraged a much greater use of cars resulting in a net increase in</p><p>carbon dioxide (CO2) emissions.</p><p>4. Waste</p><p>Minimising waste through greater off-site fabrication and modular</p><p>planning. Sorting and recycling of off-cuts, etc. to avoid landfill costs.</p><p>5. Water</p><p>Harvesting grey water and rainwater for use in toilets and irrigation.</p><p>Minimising hard areas to reduce run-off including permeable car park</p><p>surfaces and porous paviors.</p><p>6. Biodiversity</p><p>Design landscape to support local flora and fauna. Preserve existing</p><p>mature trees and generally ensure the well-being of wildlife.</p><p>Environmental considerations in the</p><p>design of offices</p><p>The first task is to persuade the clients of the benefits of environmental</p><p>and energy efficient design. There is now convincing evidence that</p><p>‘green buildings pay’ (see Edwards, B. (ed.) (1998) Green Buildings Pay,</p><p>E & F Spon, the outcome of an RIBA conference).</p><p>● It is important that all members of the design team share a common</p><p>goal and if possible have a proven track record in achieving that</p><p>goal. From the earliest outline proposals through to construction</p><p>and installation, the design process should be a collaborative effort.</p><p>Integrated design principles should be the rule from the first</p><p>encounter with a client.</p><p>● The first aim should be to maximise passive systems to reduce the</p><p>reliance on active systems which use energy.</p><p>● It is important that, at the outset, costs are calculated in a compos-</p><p>ite manner so that capital and revenue costs are considered as a sin-</p><p>gle accountancy feature. This will help to convince clients that any</p><p>extra capital expenditure is cost effective, even for buildings to be</p><p>let or sold on.</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 128</p><p>LOW ENERGY TECHNIQUES FOR NON-DOMESTIC BUILDINGS</p><p>129</p><p>● Clients should be required to explain in detail the nature of office</p><p>routines so that these can be properly matched to operational</p><p>programmes.</p><p>● The claims made for advanced technology do not always match</p><p>performance. It is important to select appropriate technology which</p><p>achieves the best balance between energy efficiency, occupant</p><p>comfort and ease of operation and maintenance. At the same time,</p><p>the best compromise should be reached between optimum per-</p><p>formance and the requirements for the majority of the year. To provide</p><p>significantly greater capacity for just a few days of the year is not</p><p>best practice.</p><p>● Lighting requirements should be clearly assessed to discriminate</p><p>between general lighting and that required at desktop level.</p><p>● On completion building managers should be selected for their abil-</p><p>ity to cope with the complexities of the chosen building manage-</p><p>ment system (BMS).</p><p>● Appropriate monitoring is necessary to be able to assess from day</p><p>to day how systems are performing. The cost of submeters, hours-</p><p>run recorders, etc. give valuable returns for a small cost. Energy</p><p>costs should be identified with specific cost centres.</p><p>Passive solar design</p><p>Planning and site considerations</p><p>Whether it is important to encourage or exclude solar radiation, it is</p><p>necessary to appreciate the degree to which solar access is available,</p><p>so that the likelihood of solar heat gain can be determined. At the ear-</p><p>liest stage of design one must consider the following parameters in</p><p>relation to the site:</p><p>● the sun’s position relative to the principal facades of the building</p><p>(solar altitude and azimuth);</p><p>● site orientation and slope;</p><p>● existing obstructions on the site;</p><p>● potential for overshadowing from obstructions</p><p>outside the site</p><p>boundary.</p><p>For the development itself, the following factors need consideration:</p><p>● grouping and orientation of buildings;</p><p>● road layout and services distribution;</p><p>● proposed glazing types and areas, and facade design;</p><p>● nature of internal spaces into which solar radiation penetrates.</p><p>Chapter 5 referred to the stereographic sun chart and computer pro-</p><p>grams as a means of assessing the level of insolation enjoyed by a</p><p>building. Physical models can also be tested by means of the heliodon.</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 129</p><p>The thermal efficiency of a building can also be affected by its plan</p><p>form and orientation in respect of the prevailing wind direction. There</p><p>are a number of guidelines:</p><p>● The larger building elevation should not face into the predominating</p><p>wind direction, i.e. the long axis should be parallel to the wind flow.</p><p>● Tall buildings should, where possible, have a facade which is stag-</p><p>gered and stepped back away from the wind; protection for pedes-</p><p>trians can be provided by use of canopies and podiums which reduce</p><p>downdraught at ground level; curved facades moderate the impact</p><p>of wind, for example the Swiss Re Offices, London, pp. 157–58.</p><p>● Sheer vertical faces to tall buildings can generate substantial down-</p><p>draughts, which can obstruct pedestrian access, and even be dan-</p><p>gerous. An example is the 19 storey Arts Tower in the University of</p><p>Sheffield where the downdraught has knocked people over close to</p><p>the entrance.</p><p>● Buildings can be grouped in irregular arrays, but within each group</p><p>the heights should be similar and spacing between them kept to a</p><p>minimum (no more than about a ratio of 2 : 1 in building heights).</p><p>● Building layout should avoid creating a tunnelling effect between</p><p>two adjacent buildings.</p><p>Construction technologies</p><p>The building envelope</p><p>Walls and rainscreens The glazed curtain wall has advanced consider-</p><p>ably since it came into vogue in the 1960s. The repository for knowledge</p><p>in this context is the Centre for Window and Cladding Technology</p><p>(www.cwct.co.uk). Metal panel systems are now available with integral</p><p>insulation, for example EDM Spanwall which uses flat metal sheets pres-</p><p>sure bonded to the insulation core. Precast concrete panels also come</p><p>with integral insulation. Trent Concrete has introduced an insulated con-</p><p>crete sandwich under the name of Hardwall Cladding. The Ocean</p><p>Terminal at Leith completed in 2001 is a good example of this technol-</p><p>ogy. Often these panels have an exterior finish of stone or reconstructed</p><p>stone.</p><p>Climate facades The glass curtain wall is a familiar feature of office</p><p>and institutional buildings dating from the 1950s, though the feature</p><p>first appeared in the US at the end of the nineteenth century. Liverpool</p><p>can boast a number of office buildings that point the way to the glass</p><p>curtain wall such as Oriel Chambers in Water Street, designed by Peter</p><p>Ellis and completed in 1864.</p><p>The technique was conceived at a time when energy was cheap</p><p>and plentiful and there was no glimmer of global warming. Buildings</p><p>challenged the environment. Now there is mounting pressure to design</p><p>buildings which operate in harmony with nature, making the most of</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>130</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 130</p><p>solar resources. The demand for increasing energy efficiency led first to</p><p>the introduction of double glazing. Now things have moved on with the</p><p>incorporation of a second inside skin of glazing creating what is termed</p><p>a ‘climate facade’ or alternatively an ‘active facade’.</p><p>These are terms for facades that play an active role in controlling</p><p>the internal climate of offices in which there is an optimum requirement</p><p>for daylight.</p><p>The active facade fulfils a variety of functions. It:</p><p>● offers room daylight control;</p><p>● acts as an active and passive solar collector;</p><p>● offers excess solar heat protection;</p><p>● minimises room heat loss;</p><p>● serves as a plenum for ventilation supply and extract air;</p><p>● facilitates heat recovery.</p><p>An example of a climate facade building is the office development at</p><p>88 Wood Street in the City of London by the Richard Rogers Partnership</p><p>(RRP). The requirement was for floor to ceiling glazing which can create</p><p>a problem of solar gain which is exacerbated by the heat from comput-</p><p>ers and, in this case, a high services loading. The facade developed by</p><p>RRP and Ove Arup and Partners consists of a double glazed external</p><p>skin made up of some of the world’s largest double glazed units meas-</p><p>uring 3 m � 3.25 m and weighing 800 kg. Then there is a 140 mm gap</p><p>and a third inner leaf of glass with openable units which completes the</p><p>facade. Within the cavity are venetian blinds with perforated slats to</p><p>control sunlight. The aesthetic appeal of the structure is enhanced by</p><p>the use of extra white glass or ‘Diamond White’ glass by the manufac-</p><p>turers Saint Gobain.</p><p>Air from the offices is drawn into the main perimeter extract ducts</p><p>within the cavity via plenum ducts within a suspended ceiling and then</p><p>expelled at roof level. Photocells on the roof monitor light conditions</p><p>and control the venetian blinds to one of three positions according to</p><p>the level of glare. When the blinds are closed they act as a heat sink</p><p>whilst the perforations admit a measure of natural light. The result is</p><p>that there are substantial savings in the energy normally needed to cool</p><p>such spaces. There is also a high rate of air change in the building at</p><p>double the average for a typical office block (Figures 11.1 and 11.2).</p><p>Another building with an active facade is Portcullis House, the</p><p>adjunct to the Houses of Parliament by Michael Hopkins and Partners.</p><p>Windows are triple glazed with mid-pane retractable blinds designed</p><p>to absorb solar gain. The outer double glazed element is Low E glass</p><p>with argon gas. The cavity is ventilated by room extract air, and, at the</p><p>same time, it acts as a solar collector. The result is a summer solar heat</p><p>gain of less than 25 W/m2 across a 4.5 m deep room.</p><p>The glazing incorporates a light shelf to maintain daylight levels</p><p>when solar shading is active. The shelf has a corrugated reflective</p><p>LOW ENERGY TECHNIQUES FOR NON-DOMESTIC BUILDINGS</p><p>131</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 131</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>132</p><p>Figure 11.1</p><p>Offices, 88 Wood Street, City of</p><p>London</p><p>Figure 11.2</p><p>Sections through the facade of</p><p>88 Wood Street</p><p>surface to maximise high altitude sky light but reject short wave low</p><p>level radiation. This almost doubles daylight levels in north facing</p><p>rooms where adjacent buildings obstruct a view of the sky (Figure 11.3).</p><p>A sealed facade does not mean the individual user has no con-</p><p>trol over ventilation. There are manual trim controls over air supply,</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 132</p><p>LOW ENERGY TECHNIQUES FOR NON-DOMESTIC BUILDINGS</p><p>133</p><p>volume, radiator output, blinds, artificial lights and a daylight dimming</p><p>override.</p><p>This is an outstanding example of a building that minimises</p><p>reliance on services engineering. It is claimed that the integrated</p><p>approach to the design has resulted in simplified engineering solutions</p><p>and a considerable saving in energy as against a standard naturally</p><p>ventilated building.</p><p>Another kind of active facade is one which incorporates solar</p><p>cells. Commercial buildings have perhaps the greatest potential with</p><p>PV cells integrated into their glazing as well as being roof mounted.</p><p>Even at the present state of the technology, Ove Arup and Partners</p><p>estimate that one third of the electricity needed to run an office com-</p><p>plex could come from PVs with only a 2 per cent addition to the build-</p><p>ing cost. The main advantage of commercial application is that offices</p><p>use most of their energy during daylight hours. The case study of the</p><p>ZICER building in the University of East Anglia will serve as an example</p><p>(Chapter 18).</p><p>One of the challenges of the next decades will be to retrofit build-</p><p>ings with PVs. In the UK a pioneer scheme is the Northumberland</p><p>Building for the University of Northumbria in Newcastle where cells</p><p>have been</p><p>applied to the spandrels beneath the continuous windows.</p><p>To date it has achieved an average daily output of 150 kWh. Based</p><p>on this figure it is expected that the cost of the PVs will be paid back in</p><p>three years thanks to a substantial subsidy. After this it will continue to</p><p>produce electricity free of cost for about 20 years. It is estimated that</p><p>the annual saving in CO2 emissions from this building alone will be of</p><p>the order of 6 tonnes.</p><p>Currently the Co-Operative Headquarters building in Manchester</p><p>is retro-fitting PVs to the south elevation of its circulation tower as part</p><p>of a refurbishment programme.</p><p>Given the abundance of information and advice available, design-</p><p>ers should now be able to grasp the opportunities offered by such tech-</p><p>nologies which also allow exploration of a range of new aesthetic</p><p>options for the building envelope.</p><p>This will increasingly be a preferred option as the cost of fossil fuel</p><p>rises under the twin pressures of diminishing reserves and the need to</p><p>curb CO2 emissions. The Solar Offices of Doxford International by</p><p>Studio E Architects located near Sunderland is a pioneer example of this</p><p>tactic in the UK. This is a speculative office development which offers the</p><p>advantage of much reduced power consumption of 85 kWh/m2/year as</p><p>against the normal air conditioned office of up to 500 kWh/m2/year. The</p><p>73 kW (peak) array of over 400 000 photovoltaic cells on the facade pro-</p><p>duces 55 100 kWh per annum which represents one third to one quarter</p><p>of the total anticipated electrical consumption (Figures 11.4 and 11.5).</p><p>The Doxford Office is modest compared with the German govern-</p><p>ment In-service Training Centre called Mont Cenis at Herne Sodingen</p><p>in the Ruhr.</p><p>Figure 11.3</p><p>Portcullis House; cutaway section of</p><p>facade</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 133</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>134</p><p>The Mount Cenis Government Training Centre is one of the world’s</p><p>most powerful solar electric plants and is a spectacular demonstra-</p><p>tion of the country’s commitment to rehabilitate this former industrial</p><p>region whilst also signalling the country’s commitment to ecological</p><p>development (Figure 11.6).</p><p>After the demise of heavy industry the Ruhr became a heavily</p><p>polluted wasteland which prompted the government of North-Rhine</p><p>Westphalia to embark on an extensive regeneration programme covering</p><p>800 square kilometres.</p><p>The building is, in effect, a giant canopy encompassing a variety of</p><p>buildings and providing them with a Mediterranean climate. At 168 m</p><p>long and 16 m high the form and scale of the building has echoes of the</p><p>huge manufacturing sheds of former times. A timber structural frame of</p><p>rough hewn pine columns is a kind of reincarnation of the forests from</p><p>which they originated.</p><p>The structure encloses two three-storey buildings either side of an</p><p>internal street running the length of the building (Figure 11.7). Their</p><p>concrete structure provides substantial thermal mass, balancing out</p><p>Figure 11.4</p><p>Doxford Solar Offices</p><p>Figure 11.5</p><p>Interior, Doxford Solar Office</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 134</p><p>LOW ENERGY TECHNIQUES FOR NON-DOMESTIC BUILDINGS</p><p>135</p><p>both diurnal and seasonal temperature fluctuations. Landscaped</p><p>spaces provide social areas which can be used all year in a climate akin</p><p>to the Côte d’Azur. Sections of the facade can be opened in summer to</p><p>provide cross-ventilation.</p><p>The building is designed to be self-sufficient in energy. The roof</p><p>and facade incorporate 10 000 m2 of PV cells integrated with glazed</p><p>panels. Two types of solar module were employed: monocrystalline cells</p><p>with a peak efficiency of 16 per cent and lower density polycrystalline</p><p>cells at 12.5 per cent. These provide a peak output of 1 megawatt. Six</p><p>hundred converters change the current from DC to AC to make it com-</p><p>patible with the grid. A 1.2 MW battery plant stores power from the PVs,</p><p>balancing output fluctuations. The power generated greatly exceeds the</p><p>Figure 11.6</p><p>Mount Cenis In-service Training</p><p>Centre, Herne – Sodingen, Germany</p><p>Figure 11.7</p><p>Mount Cenis ground floor plan</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 135</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>136</p><p>needs of the building at 750 000 kWh per year. German policy on</p><p>renewables makes exporting to the grid a profitable proposition.</p><p>This is not the only source of energy generation. The former mines</p><p>in the area release more than one million cubic metres of methane</p><p>which is used to provide both heat and power. Capturing the gas in this</p><p>way results in a reduction of carbon dioxide emissions of 12 000 tonnes.</p><p>This complex is an outstanding example of an alliance between</p><p>green technology and aesthetics. The architects, Jourda and Perraudin,</p><p>Paris, designed the distribution of PV panels to reflect the arbitrary dis-</p><p>tribution of clouds by means of six different types of module with dif-</p><p>ferent densities creating subtle variations to the play of light within the</p><p>interior. It all adds up to an enchanting environment of spaciousness,</p><p>light and shade. At the same time it affords a graphic reminder that</p><p>regenerated industrial landscapes do not have to be populated by</p><p>featureless utilitarian sheds.</p><p>Floors and ceilings The undersides of floors have a crucial role to play</p><p>in determining the effective thermal mass of a structure. Traditionally</p><p>concrete plank or slab floors had ceilings suspended below them to</p><p>house services. Now there are increasing examples of the system being</p><p>reversed with the floor above the slab raised to provide space for ducts</p><p>and other services. The soffit of the concrete floor is free of finishes, the</p><p>purpose being to improve the effectiveness of the thermal mass and</p><p>radiate stored heat in colder temperatures and ‘cooling’ in hot condi-</p><p>tions. In summer, night air is passed through ducts to cool the slab,</p><p>which then, during the day, radiates cooling into the workplace. Such</p><p>thermal mass features are sometimes called ‘thermal flywheels’ or</p><p>dampeners since they flatten the peaks and troughs of temperature.</p><p>One of the most aesthetically and environmentally suitable meth-</p><p>ods of achieving radiative thermal mass is by barrel vaults, as employed</p><p>in Portcullis House (Figure 11.8) and Wessex Water Operational Centre</p><p>near Bath by Bennetts Associates. It is important that the slabs are not</p><p>carried through to the facade in order to avoid a major thermal bridge.</p><p>To recapitulate, a thermal bridge is a route whereby cold is able to</p><p>bypass wall insulation.</p><p>A proprietory deck system which incorporates ducts to transport</p><p>both warm and cool air is Termodeck from Sweden. This was used in the</p><p>Elizabeth Fry Building in the University of East Anglia to good effect.</p><p>Air is passed through the ducts at low velocity with stale air drawn into</p><p>grilles over light fittings and then its heat extracted in a heat recovery</p><p>unit before being expelled to the open air. There is no recirculation of</p><p>air, yet this is one of the most energy efficient buildings of the 1990s due</p><p>to very high levels of insulation and air tightness. For further information</p><p>see Smith and Pitts, Concepts in Practice – Energy, Batsford, 1999.</p><p>Whilst the popular way to moderate the peaks and troughs of exter-</p><p>nal temperature as it affects building interiors is to exploit thermal mass,</p><p>there is an alternative which is to use a phase change material on internal</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 136</p><p>LOW ENERGY TECHNIQUES FOR NON-DOMESTIC BUILDINGS</p><p>137</p><p>surfaces. A system is now on the market which enables lightweight</p><p>structures to enjoy the benefits of thermal mass. It is based on paraffin</p><p>wax which is a phase change material. The wax is micro-encapsulated</p><p>within gypsum plaster. The wax stores heat up to its melting point.</p><p>This can be adjusted to a range of temperatures according to the</p><p>requirements of the material that supports it. As the wax stores heat its</p><p>temperature does not rise until it reaches melting point which is its</p><p>maximum storage capacity.</p><p>Night-time cooling causes the wax to solidify and release the</p><p>stored heat to warm the interior space. This makes the system</p><p>particu-</p><p>larly suitable for offices which are vacant at night and which can be</p><p>vented to the outside.</p><p>The wax is encapsulated within minute plastic balls to form micro-</p><p>capsules in powder form which is mixed with plaster in a ratio of</p><p>between 1 : 5 and 2 : 5 by weight. The mix is sprayed to walls. It is</p><p>claimed that a plaster coating of 6 mm has the same absorbent capacity</p><p>as a 225 mm masonry wall.</p><p>In an office context this material is ideal for facing internal parti-</p><p>tions, reducing or even eliminating the need for mechanical ventilation.</p><p>Up to spring 2004 ten buildings have been equipped with the system</p><p>which was developed by the Fraunhofer Institute for Solar Energy</p><p>Systems in Freiburg (e-mail: schossig@ise.fraunhofer.de).</p><p>Figure 11.8</p><p>Vaulted floors with exposed soffits,</p><p>Portcullis House</p><p>AIAC-Ch11.qxd 03/25/2005 17:22 Page 137</p><p>138</p><p>Chapter</p><p>Twelve</p><p>Ventilation</p><p>Natural ventilation</p><p>Part of the reaction against the sealed glass box concept of offices has</p><p>been to explore the possibilities of creating an acceptable internal climate</p><p>by natural means. This has caused a reappraisal of traditional methods</p><p>including those employed in hot climates for two millennia or more.</p><p>Internal air flow and ventilation</p><p>Air flow in the interior of buildings may be created by allowing natural</p><p>ventilation or by the use of artificial mechanical ventilation or air condi-</p><p>tioning. The production of buildings using more than one of these</p><p>options is becoming more frequent. Such buildings are said to be</p><p>‘mixed-mode’. The overriding principle should be to minimise the need</p><p>for artificial climate systems and one way to achieve this is to make</p><p>maximum use of natural ventilation in conjunction with climate sensitive</p><p>design techniques for the building fabric.</p><p>Natural ventilation is possible due to the fact that warm air is</p><p>lighter than cold air and therefore will tend to rise in relation to cold air.</p><p>As it rises, colder air is drawn in to compensate: the buoyancy principle.</p><p>If air flow is to be encouraged to help provide natural ventilation and</p><p>cooling the following are desirable design features:</p><p>● Plan form should be shallow to allow for the possibility of cross-</p><p>ventilation.</p><p>● The most straightforward system of cross flow ventilation is where</p><p>fresh air is provided with routes through a building from the windward</p><p>to leeward side. In most office situations this can be considered as</p><p>a supplement to the main ventilation strategy. Openings on oppo-</p><p>site walls to allow cross-ventilation are better than on one or more</p><p>adjacent walls.</p><p>● Building depth should not be more than about five times the floor</p><p>to ceiling height if cross-ventilation is to be successful.</p><p>● For single sided ventilation, depth should be limited to about two</p><p>and a half times the floor to ceiling height.</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 138</p><p>VENTILATION</p><p>139</p><p>● Minimum opening areas should be about 5 per cent of floor area to</p><p>provide sufficient flow.</p><p>● Continuous, secure background ventilation should be available</p><p>using trickle vents and other devices.</p><p>● Windows should be openable, but able to provide controlled air</p><p>flow. This is particularly difficult in high rise buildings but its prob-</p><p>lems have been addressed in the 40 storey Swiss Re building in the</p><p>City of London (see pp. 157–159).</p><p>● Atria and vertical towers can be incorporated into the design to</p><p>allow the stack effect to draw air through the building, though care</p><p>in meeting fire and smoke movement restrictions may determine</p><p>the limits of what is possible.</p><p>● The effectiveness of natural ventilation and cooling can be improved</p><p>by the use of low energy controlled lighting and low energy office</p><p>equipment, thus reducing internal heat gain.</p><p>The ventilation system most obviously borrowed from the past is the</p><p>use of the thermal chimney exploiting the buoyancy principle. A thermal</p><p>chimney which is warmed by the sun accelerates the process, causing</p><p>cooler air to be drawn into the building at ground level. If the chimney</p><p>has a matt black finish it will absorb heat and increase the rate of</p><p>buoyancy. Portcullis House, admirably demonstrates this technology</p><p>(Figures 12.1 and 12.11). In fact this building is one of the most overt</p><p>demonstrations of the dynamics of natural ventilation, with external ris-</p><p>ing ducts carrying the warmed air from the offices to a thermal wheel on</p><p>the roof before being expelled. Fresh air, in this case, is drawn in at high</p><p>level assisted by the thermal wheel (Figures 12.11, 12.12 and 12.13).</p><p>Figure 12.1</p><p>Portcullis House, Westminster, London</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 139</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>140</p><p>Unassisted natural ventilation</p><p>Pioneers of natural ventilation are Alan Short and Brian Ford in associa-</p><p>tion with Max Fordham. Their first groundbreaking building in the UK</p><p>was the Queen’s Engineering Building at Leicester de Montfort</p><p>University (Short Ford and Partners). This building has been well docu-</p><p>mented and a particularly useful reference is Thomas, R. (ed.) (1996)</p><p>Environmental Design, E & FN Spon.</p><p>Maintaining the principle of pure natural ventilation without</p><p>mechanical assistance is the Coventry University Library, the Lanchester</p><p>Building, by architects Short and Associates. The environmental strat-</p><p>egy was developed in association with Brian Ford. This is a deep plan</p><p>building making it impossible to employ cross flow ventilation from</p><p>perimeter windows. There is also the problem of a raised ring road</p><p>close to the site generating noise and pollution. Accordingly perimeter</p><p>windows are sealed (Figure 12.2).</p><p>The solution was to provide each quadrant of the floor plan with</p><p>large lightwells doubling up as air delivery shafts. The buoyancy of rising</p><p>warm air draws fresh air into plenums below floor level to the base of</p><p>each light tower. From here the air is drawn upwards through preheating</p><p>coils to be released to rooms at floor level. By now the air has reached</p><p>18�C. Additional warmth is provided by perimeter radiators. The air is</p><p>then drawn into the exit stacks spaced around the external walls.</p><p>‘Termination’ devices at the top of the stacks ensure that prevailing</p><p>winds will not push air back down the stacks (Figures 12.3 and 12.4).</p><p>In a building relying solely on the buoyancy of natural ventilation,</p><p>control is critical. The building energy management system (BEMS)</p><p>Figure 12.2</p><p>Coventry University library (courtesy</p><p>of Marshalls plc)</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 140</p><p>VENTILATION</p><p>141</p><p>FIRST FLOOR PLAN</p><p>SW</p><p>SE</p><p>VENTILATION STACK ROOF PLAN</p><p>NW</p><p>Figure 12.3</p><p>Plans, Coventry University library</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 141</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>142</p><p>Section through central atrium (air outlet)</p><p>Warm Exhaust air out</p><p>Section through perimeter lightwell (air inlet)</p><p>Fresh Air intake</p><p>Figure 12.4</p><p>Air circulation paths</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 142</p><p>VENTILATION</p><p>143</p><p>adjusts the outlet opening sizes according to outside temperature and</p><p>the CO2 and temperature readings in each zone of the building. It is</p><p>tuned to meet the optimum fresh air requirement compatible with the</p><p>minimum ventilation rate (Figure 12.4).</p><p>The BEMS controls dampers which allow night air to flow through</p><p>the building, cooling the exposed thermal mass during the summer. This</p><p>is a BEMS which is driven by a self-learning algorithm, meaning that it</p><p>should progressively optimise the system, learning by its mistakes.</p><p>Heat losses through the fabric of the building are minimised by</p><p>good insulations standards: U � 0.26 W/m2K for walls and less than</p><p>2.0 W/m2K for windows. The latter comprise Low E double glazing with</p><p>an argon filled cavity.</p><p>The result of avoiding mechanical ventilation and maximising</p><p>natural light is that the estimated energy demand is 64 kWh/m2 per year</p><p>which represents CO2 emissions of 20 kg/m2. This is around 85 per cent</p><p>less than the standard air conditioned building.</p><p>The building type which presents the most formidable challenge</p><p>to anyone committed to natural ventilation is a theatre. Short Ford</p><p>Associates have risen to the challenge in a spectacular fashion. There is</p><p>a considerable heat load from stage lighting as well as the audience yet</p><p>the Contact Theatre at Manchester University achieves comfort condi-</p><p>tions without help from air conditioning. This is another building by</p><p>which Alan Short, Brian Ford and Max Fordham have navigated</p><p>uncharted waters (Figure 12.5).</p><p>Figure 12.5</p><p>Contact Theatre, Manchester</p><p>University</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 143</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>144</p><p>Figure 12.6</p><p>Longitudinal and transverse sections,</p><p>Contact Theatre</p><p>The outstanding feature is the cluster of H-pot stacks over the audi-</p><p>torium reaching a height of 40 metres. The H-pot design lifts them above</p><p>neighbouring buildings to exclude downdraughts from the prevailing</p><p>south-west winds. Their volume is calculated to accelerate the buoyancy</p><p>effect and draw out sufficient hot air whilst excluding rain. Things were</p><p>made more complicated by the fact that this is a refurbishment of a 1963</p><p>auditorium, which has been largely preserved. In a theatre ventilation</p><p>and cooling are the major energy sinks. Consequently the energy load of</p><p>this building should be a fraction of the norm (Figure 12.6).</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 144</p><p>VENTILATION</p><p>145</p><p>In circumstances like this theatre it may be necessary to incorporate</p><p>attenuators in the system to minimise external noise.</p><p>The stack effect or gravity displacement is dependent on the</p><p>difference in temperature between the outside and inside air and the</p><p>height of the air column. There is considerable variation in the relative</p><p>temperatures over the diurnal and seasonal cycle. During the summer,</p><p>night-time cooling can be achieved by passing large quantities of fresh</p><p>air over the structure. Night-time cooling works when the external</p><p>temperature is lower than the internal one and gravity drives the cooler</p><p>air down into the building. In the daytime in summer when the internal</p><p>temperature has become lower than the outside temperature, it is nec-</p><p>essary to cool the incoming air, perhaps by evaporative cooling or a</p><p>heat pump. If heat is transferred from the input duct to the exhaust</p><p>duct, this further assists buoyancy.</p><p>In the UK this system can work economically up to six storeys.</p><p>Above this duct sizes may become excessively large to cope with the</p><p>volume of air.</p><p>One objection to naturally ventilated buildings is that they draw</p><p>polluted air into a building. To reduce the chance of this happening in</p><p>highly polluted areas, fresh air should be drawn into the building at</p><p>high level, above the diesel particulate matter zone. At the same time,</p><p>exhaust air which has risen through the stack effect also needs to</p><p>be expelled at high level, so a means has to be found of ensuring the</p><p>exhaust air does not contaminate the fresh air.</p><p>One way is to employ a terminal design which rotates according to</p><p>the direction of the wind. In Figure 12.7 a design of terminal is shown</p><p>which ensures that fresh air is always drawn in from the windward side</p><p>and exhaust air to the leeward side. A wind vane ensures that the ter-</p><p>minal always faces the correct direction. The aerofoil shape of the wind</p><p>direction terminal produces negative pressure on the leeward side,</p><p>assisting the expulsion of exhaust air.</p><p>In the section, Figure 12.8, the fresh air is delivered through</p><p>perimeter ducts to provide displacement ventilation. The exhaust air</p><p>can either exit through perimeter ducts or a climate facade.</p><p>Mechanically assisted ventilation</p><p>Rotating cowls was the system adopted by Michael Hopkins and</p><p>Partners with Ove Arup and Partners in the Nottingham University</p><p>Jubilee Campus (Figure 12.9). This ventilation system is the successor</p><p>to Hopkins’ and Arup’s innovations at the Inland Revenue HQ also in</p><p>Nottingham, and Portcullis House, Westminster. These led to a low</p><p>pressure mechanical system linked to heat recovery via a thermal wheel</p><p>which recovers 84 per cent of the exhaust heat.</p><p>The mechanical system requires 51 000 kWh per year and this is</p><p>supplied by 450 m2 monocrystalline photovoltaic cells. The ventilation</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 145</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>146</p><p>Figure 12.7</p><p>Combined function rotary terminal</p><p>system uses 100 per cent fresh air throughout the year. Air is introduced</p><p>directly into the roof mounted air handling units where it passed</p><p>through electrostatic filters. From here it is blown down vertical shafts</p><p>into traditional floor voids and thence to teaching rooms via low pres-</p><p>sure floor diffusers. Exhaust air uses the corridor as the extract path</p><p>from where it rises under low pressure via a staircase to the roof air</p><p>handling unit (AHU) for heat recovery then expelled through the cowl.</p><p>The vane on the cowl ensures that the extract vent faces the leeward</p><p>side according to the direction of the wind, as in the traditional oast</p><p>houses of Kent (Figure 12.10).</p><p>In most commercial and institutional buildings it is unlikely that</p><p>natural ventilation on its own will be adequate. A degree of mechanical</p><p>assistance is necessary to achieve an adequate rate of movement</p><p>around the building. Mechanical assistance should not be confused</p><p>with air conditioning which is a much more complex operation.</p><p>Mechanical ventilation involves air flow and movement provision</p><p>using fans and air and possibly supply/extract ducts. Such a system</p><p>may be able to act as the heating system in winter. However, in its basic</p><p>form, no cooling system is incorporated and therefore the lowest air</p><p>temperature which can be supplied is usually restricted to ambient</p><p>conditions. Air conditioning involves the cooling of the air using a</p><p>refrigeration system. More precise control over air temperature and</p><p>humidity can be achieved this way but usually only within a sealed</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 146</p><p>VENTILATION</p><p>147</p><p>Figure 12.8</p><p>Typical system for a naturally</p><p>ventilated office</p><p>Figure 12.10</p><p>Air handling units (AHUs) Jubilee</p><p>Campus</p><p>Figure 12.9</p><p>Jubilee Campus, University of</p><p>Nottingham</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 147</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>148</p><p>building. In many temperate climates, the thermal inertia of a building</p><p>structure, combined with controlled air flow, should be sufficient to</p><p>avoid excessive overheating except for a few hours each year.</p><p>Immediately air conditioning is specified, energy use is likely to increase</p><p>substantially.</p><p>As mentioned the inclusion of mechanical reinforcement of natu-</p><p>ral ventilation is the first step in the mixed mode direction. There are at</p><p>least four types of mixed-mode ventilation:</p><p>● Contingency – mechanical ventilation is added or subtracted from</p><p>the system as necessary.</p><p>● Zoned – different ventilation systems are provided for different</p><p>portions of the building depending upon needs.</p><p>● Concurrent – natural and mechanical systems operate together.</p><p>● Changeover – natural and mechanical systems operate as alterna-</p><p>tives (but often turn out to be concurrent because of difficulties in</p><p>zoning or changeover point control).</p><p>If mechanical ventilation is to be used to aid summer comfort levels,</p><p>the following tactics are recommended:</p><p>● draw external air from the cool side of the building;</p><p>● consider drawing air through cooler pipes or ducts (for instance</p><p>located underground) to reduce and stabilise its temperature;</p><p>ground water cooling is becoming increasingly popular;</p><p>● ensure supply air is delivered to the required point of use efficiently</p><p>to provide the most beneficial cooling effect but without uncom-</p><p>fortable draughts;</p><p>● ensure extracted air optimises heat removal by taking the most</p><p>warm and humid air;</p><p>● integrate use and positioning of mechanical systems with natural</p><p>air flow;</p><p>● in highly polluted city centre locations, air filtration down to PM5</p><p>(particulate matter down to 5 microns) is essential;</p><p>● employ night-time purging of the building to precool using lowest</p><p>temperature ambient air.</p><p>The last of these options offers many potential benefits since the air</p><p>delivered to the space can achieve a lower</p><p>planet would have</p><p>permanent summer and the other endless winter.</p><p>It has been calculated that the current orbital configuration is sim-</p><p>ilar to that of the warm interglacial period 400 000 years ago. We may</p><p>indeed be in the early stages of an interglacial episode and the accom-</p><p>panying natural warming which is being augmented by human induced</p><p>warming. (For more information on climate fluctuations over the past</p><p>million years see Houghton J. (2004) Global Warming, 3rd edn,</p><p>Cambridge University Press.)</p><p>A second factor forcing climate change is the movement of tec-</p><p>tonic plates and the resultant formation of volcanic mountains. In them-</p><p>selves mountains add to the stirring effect on the atmosphere</p><p>in concert with the rotation of the Earth. They also generate fluctuations</p><p>in atmospheric pressure, all of which affect climate.</p><p>But it is volcanic activity which can cause dramatic changes. The</p><p>surface of the Earth is constantly shifting. The collision of plates</p><p>accounts for the formation of mountains. A feature of plate tectonics is</p><p>that, when plates collide, one plate slides under the other; this is called</p><p>subduction. In the process rocks are heated and forced through the</p><p>surface as volcanoes, releasing vast quantities of debris and CO2 in the</p><p>process. In the short term this can lead to a cooling as the dust cuts out</p><p>solar radiation. In the longer term, large injections of CO2 lead to warm-</p><p>ing, since CO2 has a relatively long life in the atmosphere.</p><p>A third factor may be a consequence of the second. Paleoclimate</p><p>data show that there have been periodic surges of ice flows into</p><p>the north Atlantic which, in turn, affect the deep ocean currents, notably</p><p>the Gulf Stream. To understand why the ice flows affect the Gulf Stream</p><p>we need to look at what drives this rather special current.</p><p>Particularly salty and warm surface water migrates from the tropics</p><p>towards the north Atlantic. As it moves north it gradually becomes cold</p><p>and dense, and, as a consequence, near Greenland it plunges to the</p><p>ocean floor. This, in turn, draws warmer water from the tropics which is</p><p>why it is also called the conveyor belt or deep ocean pump. It accounts</p><p>for 25 per cent of the heat budget of northwest Europe. So, what is the</p><p>relevance of the icebergs?</p><p>As these armadas of icebergs melted as they came south they</p><p>produced huge amounts of fresh water which lowered the density of</p><p>surface water undermining its ability to descend to the ocean floor.</p><p>The effect was to shut down the conveyor belt. As a result northern</p><p>Europe was periodically plunged into arctic conditions and scientists</p><p>are concerned that there is now evidence that this process is beginning</p><p>to happen due to melting ice in the southern tip of Greenland. After the</p><p>melted iceberg water had dispersed, the conveyor started up again</p><p>CLIMATE CHANGE – NATURE OR HUMAN NATURE?</p><p>5</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 5</p><p>leading to rapid warming. This cycle occurred 20 times in 60 000 years,</p><p>and the evidence indicates that cooling was relatively slow whilst warm-</p><p>ing was rapid – 10–12�C in a lifetime. For some reason these forays of</p><p>icebergs stopped about 8000 years ago, creating relatively stable</p><p>conditions which facilitated the development of agriculture and ultimately</p><p>the emergence of urban civilisations.</p><p>A fourth factor may seem ironic, because ice ages can be triggered</p><p>by warm spells leading to the rapid expansion of forests. This, in turn,</p><p>leads to huge demands for CO2 which is drawn from the atmosphere.</p><p>The result of this stripping of atmospheric CO2 is a weakening of the</p><p>greenhouse shield, resulting in sharply dropping temperatures.</p><p>Changes in energy levels emitted by the sun are also implicated in</p><p>global fluctuations. In June 1999 the journal Nature (vol. 399, p. 437)</p><p>published research evidence from the Rutherford Appleton Laboratory</p><p>in Didcot, Oxfordshire which suggests that half the global warming</p><p>over the last 160 years has been due to the increasing brightness of the</p><p>sun. However, since 1970 the sun has become less responsible for the</p><p>warming, yet the rate of warming has been increasing, indicating that</p><p>increased greenhouse gases are the culprit. Some of the best evidence</p><p>for the climatic effects of varying levels of radiative output from the sun</p><p>comes from Africa. Sediment in Lake Naivasha in the Kenya Rift Valley</p><p>reveals the levels of lake water over the past 1000 years. Periods of high</p><p>water have higher concentrations of algae on the lake floor which trans-</p><p>lates to a higher carbon content in the annual layers of sediment. There</p><p>were long periods of intense drought leading to famine and mass</p><p>migrations, the worst being from 1000 to 1270 (Nature, vol. 403, p. 410).</p><p>Finally, we cannot ignore wider cosmic effects. The dinosaurs will</p><p>testify to the effect on climate of meteor strikes creating perpetual</p><p>night. New sites of catastrophic impacts are still being discovered on</p><p>the Earth, but if we want a true picture of the historic record of meteor</p><p>impact we can see it on Venus. The stability of that planet – no plate</p><p>movement or vegetation to hide the evidence – ensures that we have a</p><p>picture of meteor bombardment over hundreds of millennia. The Earth</p><p>will have been no different.</p><p>There is strong historic evidence that life on Earth has a precarious</p><p>foothold.</p><p>The palaeontological record shows that there have been five mass</p><p>extinctions in the recorded history of the planet. The most widely</p><p>known on the popular level is the final one which occurred at the end of</p><p>the Cretacious period 65 million years ago. It is widely attributed to one</p><p>or more massive meteorites that struck the Earth propelling huge quan-</p><p>tities of debris into the atmosphere masking the sun probably for years.</p><p>Photosynthesising plants were deprived of their energy source and</p><p>food chains collapsed resulting in the extinction of 75–80 per cent of</p><p>species, notably the dinosaurs.</p><p>However, of all the other mass extinctions, it is the third in the</p><p>sequence that warrants most attention because it has contemporary</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>6</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 6</p><p>relevance. At the end of the Permian period, 251 million years ago, a</p><p>catastrophic chain of events caused the extinction of 95 per cent of all</p><p>species on Earth. The prime cause was a massive and prolonged period</p><p>of volcanic eruptions, not from mountains but from extensive fissures in</p><p>the ground in the region which ultimately became Siberia. A chain of</p><p>events caused massive expulsions of CO2 into the atmosphere which</p><p>led to rapid warming and plant growth. This had the effect of stripping</p><p>much of the oxygen from the atmosphere leading to a collapse of much</p><p>of the biosphere. Plants and animals literally suffocated. For the next</p><p>5 million years the remaining 5 per cent of species clung to a precarious</p><p>existence. It took 50 million years for the planet to return to anything</p><p>like the previous rate of biodiversity (New Scientist, 26 April 2003,</p><p>‘Wipeout’).</p><p>The importance of this evidence lies in the fact that this mass</p><p>extinction occurred because the planet warmed by a mere 6�C over a</p><p>relatively short period in the paleoclimate timescale. Why this should</p><p>concern us now is because the world’s top climate scientists on the</p><p>United Nations Inter-Governmental Panel on Climate Change (IPCC</p><p>2002) estimated that the Earth could warm to around 6�C by the latter</p><p>part of the century unless global CO2 emissions are reduced by 60 per</p><p>cent by 2050 against the emissions of 1990.</p><p>It is the widescale evidence of anomalous climatic events cou-</p><p>pled with the rate at which they are occurring that has persuaded</p><p>the IPCC scientists that much of the blame lies with human activity.</p><p>The evidence</p><p>● There has been a marked increase in the incidence and severity of</p><p>storms over recent decades. Over the past 50 years high pressure</p><p>systems have increased by an average of three millibars whilst low</p><p>pressure troughs have deepened by the same amount, thereby</p><p>intensifying the dynamics of weather systems. Greater extremes of</p><p>the hydrological cycle</p><p>temperature than ambient</p><p>external conditions. This is particularly the case where cooler night-time</p><p>air is passed over the building’s thermal mass (often the floor slab) which</p><p>retains the ability to cool incoming daytime air. Further ‘natural cooling’</p><p>alternatives to air conditioning are summarised on pages 151–154.</p><p>An increasingly popular option is ‘displacement ventilation’. In this</p><p>case air at about one degree below room temperature is mechanically</p><p>supplied at floor level at very low velocity, usually about 0.2 metres per</p><p>second. This air is warmed by the occupants, computers or light</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 148</p><p>VENTILATION</p><p>149</p><p>fittings, etc. causing it to rise and be extracted at ceiling level. Air quality</p><p>and comfort levels can be more easily controlled using this system.</p><p>However, not all rooms may be suitable for this strategy and therefore</p><p>it should be specified only where appropriate.</p><p>Portcullis House is one of the most prestigious buildings to use</p><p>displacement ventilation (Figures 12.11 and 12.12). A mechanically</p><p>assisted ventilation system serves a network of linked floor plenums</p><p>drawing air from ducts in the facade to provide 100 per cent external air</p><p>to each room. The system incorporates high efficiency heat recovery</p><p>from solar gain, the occupants, electrical equipment and room radia-</p><p>tors. Exhaust air is carried by ducts expressed externally in the steeply</p><p>pitched roof and expelled through a series of chimneys designed to</p><p>enhance the stack effect. Heat recovery is by means of a roof mounted</p><p>rotary hygroscopic heat exchanger or ‘thermal wheel’ with 85 per cent</p><p>efficiency which is fed by air return ducts which follow the profile of the</p><p>roof. This thermal wheel is also able to recover winter moisture from</p><p>exhaust air, reducing the load on humidifiers (Figure 12.13).</p><p>Adjacent to Westminster Bridge, Portcullis House (Figure 12.1) is</p><p>situated in one of the most heavily polluted locations in London.</p><p>Ventilation air is drawn in at the highest possible level, well above the high</p><p>concentration zone of particulate matter from vehicle exhausts. This out-</p><p>side air is fed into the underfloor plenum and the displacement ventila-</p><p>tion is assisted by buoyancy action. The brief specified a temperature of</p><p>22�C plus or minus 2� so, when necessary, the ventilation air can be cooled</p><p>by ground water in two bore holes at a steady 14�C. Buoyancy ventilation</p><p>is assisted by low power fans. The full fresh air system is able to serve all</p><p>rooms equally, despite the diversity of function. This is essential for a</p><p>long-life building which may undergo numerous internal changes.</p><p>Figure 12.11</p><p>Portcullis House, section</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 149</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>150</p><p>An outstanding example of displacement ventilation being inserted</p><p>into a refurbished building is afforded by the Reichstag. By a slender</p><p>majority the German Parliament decided to move to Berlin and to</p><p>rehabilitate the Reichstag. Norman Foster was invited to submit</p><p>a design in a limited competition which he won.</p><p>The debating chamber uses displacement ventilation drawing air</p><p>again from high level above low level pollution such as PM10s (it is now</p><p>considered that PM5 should be the health threshold). The chamber</p><p>floor comprises a mesh of perforated panels covered by a porous</p><p>carpet. The whole floor, therefore, is a ventilation grille. Large ducts under</p><p>the floor enable air to be moved at low velocity, which reduces noise</p><p>and minimises the power for fans (Figure 12.14).</p><p>Figure 12.12</p><p>Portcullis House, displacement</p><p>ventilation</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 150</p><p>VENTILATION</p><p>151</p><p>Figure 12.13</p><p>Portcullis House, ventilation pathways</p><p>and detail of the thermal wheel</p><p>Finally, the critical design issues concerning mechanical ventilation</p><p>involve:</p><p>● the sizing and routing of ducts to minimise resistance and thus keep</p><p>fan size to a minimum;</p><p>● the positioning of diffusers in relation to plan and section of rooms;</p><p>● the size of diffusers to minimise noise;</p><p>● the inclusion of devices to stop the spread of fire.</p><p>Cooling strategies</p><p>Cooling strategies begin at the level of the site. Vegetation, especially</p><p>trees, provides both shade and evaporative cooling through moisture</p><p>expiration through leaves. Pools, fountains, waterfalls/cascades, sprays</p><p>and other water features all add to the evaporative cooling effect. In</p><p>studies of ‘heat island effect’ generated by buildings it was found that</p><p>clusters of trees within the heat island can produce a localised drop in</p><p>temperature of 2–3�C.</p><p>Chilled ceilings are a method of providing cooling not necessarily</p><p>associated with air flow systems. The advantages of the system are, first,</p><p>that thermal stratification affects in a room are reduced and, second, that</p><p>a chilled ceiling counterbalances the effect of thermal buoyancy, that is,</p><p>rising warm air. The ceiling may be chilled using a refrigerant. The more</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 151</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>152</p><p>environmentally benign method is to employ mechanical night-time</p><p>cooling to precool exposed floor slabs. An alternative system involves</p><p>embedding pipes in concrete floors to carry cooling water, usually from</p><p>a ground source.</p><p>Evaporative cooling</p><p>Another case of ‘nothing new under the sun’ is evaporative cooling. One</p><p>of the earliest cases of this being incorporated in a building is the</p><p>Emperor Nero’s megalomanic ‘Golden House’ which covered most of the</p><p>centre of Rome. At its centre was the domed octagon room and in one of</p><p>its sides a waterfall was inset, supplied by a mountain stream. No doubt it</p><p>performed the dual role of architectural feature and cooling device.</p><p>Evaporative cooling works on the principle that molecules in a</p><p>vapour state contain much more energy than the same molecules in a</p><p>Fresh air</p><p>intake</p><p>Hot air</p><p>Exhaust air</p><p>Natural diffused light</p><p>Air plenum</p><p>Air treatment</p><p>Figure 12.14</p><p>Displacement ventilation and natural</p><p>light in the Reichstag</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 152</p><p>VENTILATION</p><p>153</p><p>liquid state. The amount of heat required to change water into vapour</p><p>is the latent heat of evaporation. This heat is removed from the water,</p><p>hence ‘evaporative cooling’, and transferred to the vapour. So, evapo-</p><p>ration causes surfaces to cool (Thomas, R. (ed.) (1996) Environmental</p><p>Design, E & FN Spon).</p><p>Evaporative techniques include:</p><p>● air that does not already have a high moisture content can be</p><p>cooled by allowing water to evaporate into it;</p><p>● as stated, direct evaporation occurs when air passes through tree</p><p>foliage, fountains and across pools;</p><p>● evaporative cooling is produced if incoming air to a building passes</p><p>over a dampened surface, or through a spray or damp material</p><p>across windows;</p><p>● direct evaporative cooling is best in dry climates where average</p><p>relative humidity at noon in summer does not exceed 40 per cent;</p><p>● in the case of indirect evaporation, the air does not come into direct</p><p>contact with the moisture, but can be allowed to pass through tubes</p><p>or pipes which have their outer surfaces moistened.</p><p>An example of a design which incorporates evaporative cooling is the</p><p>Jubilee Campus at Nottingham University. Sloping glazing directs air</p><p>which has previously passed across an extensive open air pool into an</p><p>atrium between teaching and office units. Orientation ensures that the</p><p>prevailing wind is in the right direction (Figure 12.15).</p><p>Figure 12.15</p><p>Directed evaporative cooling, Jubilee</p><p>Campus</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 153</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>154</p><p>Additional cooling strategies</p><p>● Shading should be compatible with daylight provision and passive</p><p>solar gain, at the same time causing minimum interference with</p><p>external views.</p><p>● Use heat absorbing and heat reflecting glasses.</p><p>● In traditional Mediterranean building, the outer surfaces were</p><p>painted light colours to reflect a portion of the heat gain; we can</p><p>learn from this.</p><p>The ecological tower</p><p>Surely an oxymoron? The orthodox ‘green’ would rule out anything</p><p>above about</p><p>12 storeys since this is the height at which natural ventila-</p><p>tion in the western European climate zone is said to become impracti-</p><p>cable. Tower blocks usually require a heavy engineering services</p><p>system. Also the construction energy costs rise significantly every five</p><p>floors or so.</p><p>However, the ecological tower block has its advocates, most notably</p><p>Ken Yeang from Kuala Lumpur. He pioneered the idea of gardens in the</p><p>sky coupled with natural ventilation. To cope with the wind speeds (up to</p><p>40 metres per second at 18 storeys) he uses wing wind walls and wind</p><p>scoops which deflect the wind into the centre of the building.</p><p>The first manifestation of these principles in the west was the</p><p>Commerzbank in Frankfurt (Figure 12.16). This began life as a limited</p><p>competition for an office headquarters comprising 900 000 square feet</p><p>of office space and 500 000 square feet of other uses. The brief was</p><p>clear that it should be an ecological building in which energy efficiency</p><p>and natural ventilation played a crucial role. At that time the Green</p><p>Party was in control of the city. In the winning design by Norman Foster</p><p>Associates, a 60-storey three-sided building wraps round an open cen-</p><p>tral core ascending the full height of the building (Figure 12.17). The</p><p>most remarkable feature of the design is the incorporation of open</p><p>gardens. The nine gardens each occupy four storeys and rotate round</p><p>the building at 120 degrees enabling all the offices to have contact with</p><p>a garden.</p><p>The gardens are social spaces where people can have a coffee or</p><p>lunch and each one ‘belongs’ to a segment of office space accommo-</p><p>dating 240 people. As the architects put it: ‘we’re breaking the building</p><p>down into a number of village units’. This is extremely important in</p><p>reducing the scale of the place for its occupants. The gardens feature</p><p>vegetation from North America, Japan and the Mediterranean according</p><p>to their height above ground.</p><p>The natural ventilation enters through the top of the gardens</p><p>passing into the central atrium. The atrium is subdivided into 12-storey</p><p>units and within 12 floors there is cross-ventilation from the gardens in</p><p>AIAC-Ch12.qxd 03/25/2005 17:23 Page 154</p><p>VENTILATION</p><p>155</p><p>Figure 12.16</p><p>Commerzbank, Frankfurt</p><p>the three directions (Figure 12.18). Air quality is good, enhanced as it is</p><p>by the greenery. It is estimated that the natural ventilation system will</p><p>be sufficient for 60 per cent of the year. When conditions are too cold,</p><p>windy or hot, the building management system activates a backup</p><p>Figure 12.17</p><p>Commerzbank typical floor plan</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 155</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>156</p><p>Figure 12.18</p><p>Natural ventilation paths in the</p><p>Commerzbank</p><p>ventilation system which is linked to a chilled ceiling system that oper-</p><p>ates throughout the building.</p><p>The curtain wall design is on Klimafassade (climate facade) princi-</p><p>ples. Air enters at each floor in the facade into a 200 mm cavity where it</p><p>heats up and passes out through the top of the cavity, which is, in</p><p>effect, a thermal chimney. The climate facade consists of a 12 mm glass</p><p>outer skin that has been specially coated to absorb radar signals, pre-</p><p>sumably from the airport. The inner skin of the facade is Low E double</p><p>glazing giving the overall system a high U-value. There are permanent</p><p>vents in the outer skin whilst the inner double glazed element has</p><p>openable vents which can be overriden by the BMS when circumstances</p><p>demand it. Motorised aluminium blinds in the cavity provide solar</p><p>shading. It is calculated that the ventilation system will use only 35 per</p><p>cent of the energy of an air conditioned office.</p><p>This is a remarkable attempt to create an extremely high tower</p><p>block which minimises its environmental impact whilst also providing</p><p>optimum comfort and amenity for its occupants. It also demonstrates</p><p>how bioclimatic architecture is subject to the vagaries of political</p><p>fortune. If the Greens had not had their brief moment of glory it is likely</p><p>that this building would never have happened.</p><p>In 2004 Number 30 St Mary Axe, the London headquarters of the</p><p>international reinsurers Swiss Re, was completed (Figure 12.19). It is</p><p>claimed by its architects Foster and Partners to be the first environ-</p><p>mental skyscraper in the City. At 40 storeys its circular plan and cone-</p><p>like shape differentiate it from all other high buildings in London. The</p><p>question is whether this is a piece of architectural whimsy or a form</p><p>that arises from a logical functional brief. There is no doubt as to its</p><p>genetic origin which is the Commerzbank in Frankfurt with its</p><p>triangular plan and four-storey atria which rotate around the plan</p><p>(Figures 12.19–12.21).</p><p>The idea of an atrium space easily accessible at all levels has now</p><p>evolved into six spiral light wells that have a platform at every sixth</p><p>floor. The spirals are accentuated in darker glass on the elevation.</p><p>Triangular in plan they serve to provide both light and ventilation. The</p><p>curved aerodynamic shape ensures then even high winds slide off the</p><p>surfaces making minimum impact. This, in turn, has made it possible to</p><p>incorporate motorised opening windows in the atria to assist natural</p><p>ventilation. Floors between the break-out spaces have balconies to the</p><p>atria. The 39th floor is a restaurant offering spectacular views for the</p><p>privileged few.</p><p>According to the services engineers Hilson Moran, the ventilation</p><p>system would be boosted by air pressure variation produced by the</p><p>circular form driving the natural ventilation cycle. The atria/lightwells</p><p>provide natural ventilation and act as ‘lungs’ for the building, providing</p><p>natural ventilation for 40 per cent of the year. Overall the ventilation</p><p>system is mixed mode employing air conditioning which is perhaps</p><p>inevitable in a building of this height and location. However, the energy</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 156</p><p>VENTILATION</p><p>157</p><p>Figure 12.19</p><p>Swiss Re Insurance Group</p><p>headquarters, London</p><p>impact of the air conditioning is reduced by a series of heat recovery</p><p>units. Both natural and mechanical ventilation systems are controlled</p><p>by an intelligent building management system.</p><p>The external skin is a climate facade consisting of an external</p><p>double glazed external screen and single internal glazing. The space</p><p>between serves as a ventilated cavity, removing warm air in summer and</p><p>providing insulation in winter. Solar controlled blinds are positioned</p><p>within the cavity.</p><p>A circular plan has the advantage of maximising daylight in the</p><p>office floors which are situated around the perimeter with circulation</p><p>taking up the core of the building.</p><p>Altogether the environmental attributes of the design result in an</p><p>estimated energy consumption of 150 kWh/m2 per year which repre-</p><p>sents a 50 per cent saving compared with a traditional, good practice</p><p>design, fully serviced office development of similar size.</p><p>This building highlights one of the dilemmas of bioclimatic archi-</p><p>tecture, namely that a bespoke building may only be partly used by the</p><p>building owner. In this case Swiss Re will undertake rigorous energy</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 157</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>158</p><p>management. However, much of the tower will be let out with no guar-</p><p>antee of a similar quality of energy management. The worst case</p><p>scenario is that the system will be allowed to default to air conditioning</p><p>which will negate the energy efficiency targets of the designers.</p><p>Nearby, in Aldgate, Nicholas Grimshaw and Partners are construct-</p><p>ing a 49-storey office building, the Minerva Tower (Figure 12.22).</p><p>Like the previous examples in the book this will maximise natural</p><p>ventilation as part of a mixed-mode ventilation strategy within the con-</p><p>straints of a high rise building. The services engineers, Roger Preston</p><p>and Partners, reckon that if the natural ventilation capacity is used to</p><p>the full, it should produce a two thirds energy saving against a conven-</p><p>tional sealed air conditioned equivalent. Again the design makes maxi-</p><p>mum use of the climate facade principle which</p><p>adds about 3 per cent to</p><p>the cost and reduces the floor plate. When the energy savings are capi-</p><p>talised it quickly becomes clear that the extra cost is soon recovered,</p><p>offering considerable revenue benefits thereafter.</p><p>Up to the seventh floor occupants can open windows behind a</p><p>protective glass screen. Above this level the climate facade comes into</p><p>its own. This moderates the problems associated with high rise build-</p><p>ings: high wind velocity, pollution and noise. The natural ventilation</p><p>works by allowing occupants to operate double glazed windows which</p><p>open into a 650 mm space sealed from the outside by a single skin of</p><p>Figure 12.20</p><p>Ground floor plan and piazza</p><p>Figure 12.21</p><p>Upper floors with triangular atria</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 158</p><p>VENTILATION</p><p>159</p><p>Figure 12.22</p><p>Minerva Tower</p><p>glazing. Vents at the top and bottom of this void allow access for fresh</p><p>air. This means that, even at a height of 200 m, air velocity can be</p><p>moderated by vents, allowing it to enter the office space at an agree-</p><p>able velocity. The designers are optimistic that the tower will be able</p><p>to operate in natural mode for about two thirds of the year, with</p><p>mechanical ventilation only necessary in extremely hot, cold or windy</p><p>conditions.</p><p>The seasonal variations in the operation of the climate facade are</p><p>shown in Figure 12.23.</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 159</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>160</p><p>Summary</p><p>Ventilation and air movement – recommendations</p><p>● Help cool occupants by increasing air movement during day time.</p><p>● Cool the structure of building using cooler air normally available at</p><p>night.</p><p>● Plan the siting of building openings to enhance natural ventilation.</p><p>● Investigate the use of wing walls to improve air flow through</p><p>openings.</p><p>● Allow stack effect flow paths to produce ventilation air movement.</p><p>● Consider the use of solar chimneys to enhance stack air movement.</p><p>● Wind towers and wind catchers can be used to derive additional</p><p>air flow.</p><p>● Internal fans – box, oscillating and ceiling types – should be</p><p>available when alternative air flow is insufficient.</p><p>Absorption of heat gain</p><p>● Absorption cooling uses natural sources of heat to drive simple</p><p>absorption refrigeration systems.</p><p>● Lithium bromide and ammonia-based refrigerants are most</p><p>frequently used.</p><p>● Heat is removed from the building by air or liquid cooled by the</p><p>absorption system.</p><p>Radiative loss of heat</p><p>● Radiant heat loss from building surfaces can be improved by con-</p><p>sideration of the geometry of the building in relation to the sky and</p><p>other structures.</p><p>Figure 12.23</p><p>Natural ventilation in a climate facade,</p><p>Minerva 2</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 160</p><p>VENTILATION</p><p>161</p><p>● Exposed roof surfaces may allow night-time cooling in suitable</p><p>climates.</p><p>Earth cooling strategies</p><p>● The temperature of the earth below ground is generally cooler and</p><p>more stable than the air above ground.</p><p>● The earth is used to absorb heat either by building wholly or partly</p><p>underground or by passing air through ducts or passages, usually one</p><p>to three metres below the surface, prior to supply to the building.</p><p>Air conditioning</p><p>Air conditioning systems have high energy demands for heating and</p><p>particularly cooling systems. In addition the rates of air flow are often</p><p>substantially higher than with simple mechanical ventilation systems,</p><p>thus requiring heavy duty energy guzzling fans. The additional proportion</p><p>of energy consumption is not matched by a proportional increase in</p><p>comfort. The system is often operated for large fractions of the day when</p><p>a suitable building design combined with an appropriate environmental</p><p>control strategy would obviate the need for such air conditioning. The</p><p>extravagant use of air conditioning is particularly noteworthy in the</p><p>temperate climate of the United Kingdom.</p><p>There are of course some circumstances in which air conditioning</p><p>is necessary. However, its use should be justified by the particular cir-</p><p>cumstances. In general it can be asserted that climate-sensitive design</p><p>can eliminate the need for air conditioning in most instances.</p><p>Where air conditioning is deemed necessary, it likely to be of prime</p><p>importance in only a fraction of the whole building and therefore</p><p>designers should design for appropriate compartmentalisation with</p><p>the conditioned area sealed from the remainder of the building.</p><p>AIAC-Ch12.qxd 03/25/2005 17:24 Page 161</p><p>162</p><p>Chapter</p><p>Thirteen</p><p>Energy options</p><p>Electricity is the ultimate convenience source of energy which disguises</p><p>the fact that, with present methods of production and the fuel mix, it is</p><p>highly energy inefficient. At its point of use, that is, as delivered energy,</p><p>it is around 30 per cent efficient. Energy is defined as ‘primary’ and</p><p>‘delivered’. Primary energy is that which is contained in the fuel in its natu-</p><p>ral state; delivered energy is that which is in the fuel at the point of use.</p><p>At present fossil-based energy is relatively cheap because, as indi-</p><p>cated earlier, it does not carry its external costs such as the damage to</p><p>health, to forests, to buildings and above all to climate. It may soon</p><p>become politically necessary to incorporate these costs into the price of</p><p>fossil fuels which will have huge economic consequences. Meanwhile</p><p>the biggest carbon dioxide (CO2) abatement gains are to be realised in</p><p>cutting demand especially in buildings. Even at the current price of</p><p>energy green buildings can be cost effective.</p><p>It is worth noting the relative CO2 emissions between different</p><p>forms of fossil-based energy:</p><p>kg/kWh delivered</p><p>Electricity 0.75</p><p>Coal 0.31</p><p>Fuel oil 0.28</p><p>Gas 0.21</p><p>Much has been made of the UK’s switch to gas fired electricity genera-</p><p>tion, yet still electricity accounts for 750 grams of CO2 in the atmos-</p><p>phere for every kilowatt hour.</p><p>An increasingly popular way of servicing commercial and institu-</p><p>tional buildings is by combine heat and power (CHP). It can be one of</p><p>the more efficient ways of using energy. A typical distribution of total</p><p>energy output from a CHP system is</p><p>Electricity 25%</p><p>High grade heat 55%</p><p>Medium grade heat 10%</p><p>Low grade heat 10%</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 162</p><p>ENERGY OPTIONS</p><p>163</p><p>This is called the ‘energy balance’ of CHP and it is attractive for two</p><p>main reasons:</p><p>● Most of the energy of the fuel is useful.</p><p>● It can be adapted to low to zero carbon applications.</p><p>A CHP system is flexible. At present most CHP installations operate</p><p>with gas or diesel reciprocating engines or turbines for larger installa-</p><p>tions. However, even relatively small installations will soon be able to</p><p>switch to gas fired micro-turbines. Later in the decade there will prob-</p><p>ably be a considerable rise in the use of fuel cells. This is the technology</p><p>of the future.</p><p>The fuel cell</p><p>Fuel cells are electrochemical devices that generate DC electricity similar</p><p>to batteries. Unlike batteries they take their energy from a continuous</p><p>supply of fuel, usually hydrogen. The fuel cell is not an energy storage</p><p>device but may be considered as an electrochemical internal combus-</p><p>tion engine. It is a reactor which combines hydrogen and oxygen to pro-</p><p>duce electricity, heat and water. Thus its environmental credentials are</p><p>impeccable. The problem at the moment is that it is an expensive way</p><p>of producing energy. Each installed kilowatt costs $3000 to $4000;</p><p>whereas a combined cycle gas turbine system costs $400 per kilowatt.</p><p>The reason for this cost difference is that the fuel cell uses platinum as a</p><p>catalyst. However, experts think that the quantity of platinum can be cut</p><p>by a factor of 5, which will bring about a significant reduction in cost.</p><p>There will also be considerable reductions as mass production begins to</p><p>bite. The latest prediction is that the cost should fall to between $600</p><p>and $1000 per kilowatt.</p><p>Fuel cells are efficient, clean and quiet with no moving parts and</p><p>are ideal for combined heat and power application. For static cells in</p><p>buildings perhaps the most promising technology is the solid oxide</p><p>fuel cell which operates at around 800�C. Most fuel cells</p><p>work with</p><p>hydrogen. At present the most cost-effective way to obtain the hydro-</p><p>gen is by reforming natural gas. According to Amory Lovins ‘A reformer</p><p>the size of a water heater can produce enough hydrogen to serve the</p><p>fuel cells in dozens of cars’ (New Scientist, 25 November 2000, p. 41).</p><p>In that case it will not be long before it will be possible to buy a fuel cell</p><p>and reformer kit for the home which will make it independent of the</p><p>grid providing heat and power much more cheaply than is possible at</p><p>present. Considerable research effort is being directed into improving</p><p>the efficiency and lowering the cost of fuel cells because this is the tech-</p><p>nology of the twenty-first century and huge rewards await whoever</p><p>makes that breakthrough. According to David Hart of Imperial College</p><p>‘If fuel cells fulfil their potential, there is no reason why they shouldn’t</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 163</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>164</p><p>replace almost every battery and combustion engine in the world’</p><p>(New Scientist, Inside Science ‘Fuelling the Future’, 16 June 2001).</p><p>At present there are five versions of fuel cell technology. The pro-</p><p>ton exchange membrane system is the most straightforward and serves</p><p>to explain the basic principles of the fuel cell.</p><p>Proton exchange membrane fuel cell</p><p>Sometimes called the polymer electrolyte membrane fuel cell (PEMFC</p><p>in either case) it is also referred to as the solid polymer fuel cell. This is</p><p>one of the most common types of cell being appropriate for both vehi-</p><p>cle and static application. Of all the cells in production it has the lowest</p><p>operating temperature of 80�C. The cell consists of an anode and a</p><p>cathode separated by an electrolyte, usually Teflon. Both the anode</p><p>and cathode are coated with platinum which acts as a catalyst.</p><p>Hydrogen is fed to the anode and an oxidant (oxygen from the air) to</p><p>the cathode. The catalyst on the anode causes the hydrogen to split</p><p>into its constituent protons and electrons. The electrolyte membrane</p><p>allows only protons to pass through to the cathode setting up a charge</p><p>separation in the process. The electrons pass through an external cir-</p><p>cuit creating useful energy at around 0.7 volts then recombining with</p><p>protons at the cathode to produce water and heat (Figure 13.1).</p><p>To build up a useful voltage cells are stacked between conductive</p><p>bi-polar plates, usually graphite, which have integral channels to allow</p><p>the free flow of hydrogen and oxygen (Figure 13.2).</p><p>The electrical efficiency of the PEMFC is 35 per cent with a target</p><p>of 45 per cent. Its energy density is 0.3 kW/kg compared with 1.0 kW/kg</p><p>for internal combustion engines.</p><p>Figure 13.1</p><p>Basic structure and function of the</p><p>proton exchange membrane fuel cell</p><p>Figure 13.2</p><p>Fuel cell stack</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 164</p><p>One problem with the PEMFC is that it requires hydrogen of a high</p><p>degree of purity. Research activity is focusing on finding cheaper and</p><p>more robust catalysts as well as more efficient ion exchange polymer</p><p>electrolytes.</p><p>Phosphoric acid fuel cell (PAFC)</p><p>Similar to PEMFCs this cell operates in the middle temperature range</p><p>at around 200�C. This means it can tolerate some impurities. It</p><p>employs a phosphoric acid proton conducting electrolyte and platinum</p><p>or platinum–rhodium electrodes. The main difference from a PEMFC is</p><p>that it uses a liquid electrolyte.</p><p>The system efficiency is currently in the 37–43 per cent range, but</p><p>this is expected to improve. This technology seems particularly popular</p><p>in Japan where electricity costs are high and dispersed generation is</p><p>preferred. A 200 kW unit which uses sewage gas provides heat and power</p><p>for Yokohama sewage works. The largest installation to date for the Tokyo</p><p>Electric Power Company had an output of 11 megawatts – until it expired.</p><p>PAFC units have been used experimentally in buses. However, it is</p><p>likely that its future lies in stationary systems.</p><p>The New Scientist editorial referred to above predicts that ‘Larger,</p><p>static fuel cells will become attractive for hotels and sports centres,</p><p>while power companies will use them as alternatives to extending the</p><p>electricity grid.’ An example of this is the police station in Central Park,</p><p>New York, which found that installing a PAFC of 200 kW capacity</p><p>was cheaper than a grid connection requiring new cables in the park</p><p>(David Hart, op. cit.). One year after this prediction the Borough of</p><p>Woking, Surrey, UK, installed the first commercial PAFC fuel cell to</p><p>operate in the UK. It also has a capacity of 200 kW and provides heat,</p><p>cooling, light and dehumidification for the Pool in the Park recreation</p><p>centre. The fuel cell forms part of Woking Park’s larger combined heat</p><p>and power system (see p. 242).</p><p>Solid oxide fuel cell (SOFC)</p><p>This is a cell suitable only for static application, taking several hours to</p><p>reach its operating temperature. It is a high temperature cell, running at</p><p>between 800 and 1000�C. Its great virtue is that it can run on a range of</p><p>fuels including natural gas and methanol which can be reformed within</p><p>the cell. Its high operating temperature also enables it to break down</p><p>impurities. Its high temperature also removes the need for noble metal</p><p>catalysts such as platinum.</p><p>It potentially has a wide range of power outputs, from 2 to 1000 kW.</p><p>In contrast to PEMFCs the electrolyte conducts oxygen ions rather</p><p>than hydrogen ions which move from the cathode to the anode. The</p><p>ENERGY OPTIONS</p><p>165</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 165</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>166</p><p>electrolyte is a ceramic which becomes conductive to oxygen ions at</p><p>800�C. SOFCs are often structured in a tubular rather than a planar form</p><p>(as in the PEMFC) to reduce the chance of failure of the seals due to</p><p>high temperature expansion. Air (oxygen) flows through a central tube</p><p>whilst fuel flows round the outside of the structure (Figure 13.3).</p><p>According to David Hart of Imperial College ‘Solid oxide fuel cells</p><p>are expected to have the widest range of applications. Large units</p><p>should be useful in industry for generating electricity and heat. Smaller</p><p>units could be used in houses.</p><p>Alkaline fuel cells (AFC)</p><p>This fuel cell dates back to the 1940s and was the first to be fully devel-</p><p>oped in the 1960s. It was used in the Apollo spacecraft programme. It</p><p>employs an alkaline electrolyte such as potassium hydroxide set between</p><p>nickel or precious metal electrodes. Its operating temperature is 60–80�C</p><p>which enables it to have a short warm-up time. However, its energy</p><p>density is merely one tenth that of a PEMFC which makes it much bulkier</p><p>for a given output.</p><p>Molten carbonate fuel cell (MCFC)</p><p>This is a high temperature fuel cell operating at about 650�C. The</p><p>electrolyte in this case is an alkaline mixture of lithium and potassium</p><p>Figure 13.3</p><p>Solid oxide fuel cell in its tubular</p><p>configuration</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 166</p><p>carbonates which becomes liquid at 650�C and is supported by a</p><p>ceramic matrix. The electrodes are both nickel based. The operation of</p><p>the MCFC differs from that of other fuel cells in that it involves carbon-</p><p>ate ion transfer across the electrolyte. This makes it tolerate both car-</p><p>bon monoxide and carbon dioxide. The cell can consume hydrocarbon</p><p>fuels that are reformed into hydrogen within the cell.</p><p>The MCFC can achieve an efficiency of 55 per cent. The steam and</p><p>carbon dioxide it produces can be used to drive a turbine generator</p><p>(cogeneration) which can raise the total efficiency to 80 per cent – up to</p><p>twice that of a typical oil or gas fired plant. Consequently this technol-</p><p>ogy could be ideal for urban power stations producing combined</p><p>heat and power. The Energy Research Corporation (ERC) of Danbury,</p><p>Connecticut, USA, has built a 2 megawatt unit for the municipality of</p><p>Santa Clara, California, and that company is currently developing a</p><p>2.85 megawatt plant.</p><p>Development programmes in Japan and the US have produced</p><p>small prototype units in the 5–20 kW range, which, if successful, will</p><p>make them attractive for domestic combined heat and power.</p><p>The main disadvantage of the MCFC is that it uses as electrolytes</p><p>highly corrosive molten salts that create both design and maintenance</p><p>problems. Research is concentrating on solutions to this problem.</p><p>In March 2000 it was announced that researchers in the University</p><p>of Pennsylvania in Philadelphia had developed a cell that could run</p><p>directly off natural gas or methane. It did not have to be reformed to</p><p>produce hydrogen. Other fuel cells cannot run directly on hydrocar-</p><p>bons which clog the catalyst within minutes. This innovative cell uses a</p><p>copper and cerium oxide catalyst instead of nickel. The researchers</p><p>consider that cars will be the main beneficiaries of the technology.</p><p>However, Kevin Kendall, a chemist from the University of Keele, thinks</p><p>differently. According to him ‘Millions of homeowners replace their gas-</p><p>fired central heating systems in Europe every year. Within five years</p><p>they could be installing a fuel cell that would run on natural gas . . . Every</p><p>home could have a combined heat and power plant running off mains</p><p>gas’ (New Scientist, 18 March 2000). That prediction should perhaps be</p><p>raised to 2010.</p><p>International Fuel Cells (US) is testing a cell producing 5 kW to</p><p>10 kW of electricity and hot water at 120–160�C for heating. This is a res-</p><p>idential system which the US company Plug Power, which is linked</p><p>to General Electric, is marketing as the ‘GE HomeGen 7000’ domestic</p><p>fuel cell.</p><p>Professor Tony Marmont, the initiator of the fuel cell in his West</p><p>Beacon farm, considers a scenario whereby the fuel cell in a car would</p><p>operate in conjunction with a home or office. He estimates that a car</p><p>spends 96 per cent of its time stationary so it would make sense to</p><p>couple the car to a building to provide space and domestic hot water</p><p>heat. The electricity generated would be sold to the grid. The car would</p><p>be fuelled by a hydrogen grid. Until that is available a catalyser within</p><p>ENERGY OPTIONS</p><p>167</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 167</p><p>the car would reform methanol or even natural gas from the mains to</p><p>provide the hydrogen.</p><p>The reason for the intensification of research activity is the belief</p><p>that the fuel cell is the energy technology of the future in that it meets</p><p>a cluster of needs, not least the fact that it can be a genuine zero</p><p>carbon dioxide energy source. It could also relieve us of reliance on a</p><p>national grid which, in many countries, is unreliable. Perhaps the great-</p><p>est beneficiaries will initially be rural communities in developing coun-</p><p>tries who could never hope to get access to a grid supply. Access to</p><p>energy is the main factor which divides the rich from the poor through-</p><p>out the world. A cheap fuel cell powered by hydrogen electrolysed</p><p>from PV, solar-electric or small-scale hydroelectricity could be the ulti-</p><p>mate answer to this unacceptable inequality.</p><p>There is little doubt that we are approaching the threshold of the</p><p>hydrogen-based economy. Ultimately hydrogen should be available</p><p>‘on tap’ through a piped network. In the meantime reforming natural</p><p>gas, petrol, propane and other hydrocarbons to produce hydrogen</p><p>would still result in massive reductions in carbon dioxide emissions and</p><p>pollutants like oxides of sulphur and nitrogen. The domestic-scale fuel</p><p>cells will have built-in processing units to reform hydrocarbon fuels and</p><p>the whole system will occupy about the same space as a central heating</p><p>boiler.</p><p>The fuel cell will really come into its own when it is fuelled by hydrogen</p><p>produced from renewable sources like solar cells, wind- and marine-</p><p>based renewables. If tidal energy is exploited to its full potential there</p><p>will be peak surpluses of electricity which could serve to create hydro-</p><p>gen via electrolysis.</p><p>The first domestic scale fuel call was installed in the experimental</p><p>Self-Sufficient Solar House created by Fraunhofer Institute for Solar</p><p>Energy Systems in Freiburg in 1994. Its hydrogen was electrolysed from</p><p>PVs on its roof and stored in an outside tank (Figure 5.6).</p><p>In the US there are growing problems in some areas over the reli-</p><p>ability of the power supply and this is increasing the attractiveness of</p><p>fuel cells. In Portland, Oregon hydrogen extracted from methane from</p><p>a sewage works generates power sufficient to light 100 homes. The</p><p>same happens in California where sewage from the Virgenes Municipal</p><p>Water District in Calabasas reforms methane into hydrogen to supply a</p><p>fuel cell that provides 90 per cent of the power needed to run the plant.</p><p>If it were available to the grid it would power 300 homes.</p><p>The US Department of Energy plans to power two to four million</p><p>households with hydrogen and fuel cells by 2010 and ten million by 2030.</p><p>If the hydrogen is obtained from sewage, livestock waste, underground</p><p>methane or water split by PV/wind electrolysis then this programme will</p><p>certainly be one to be emulated by all industrialised countries.</p><p>Fuel cells reliant on renewable energy will be heavily dependent</p><p>on an efficient electricity storage system. At present this is one of the</p><p>main stumbling blocks to a pollution-free future.</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>168</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 168</p><p>The main barrier to the widespread adoption of fuel cells is the</p><p>cost. The US Department of Energy estimates that the current cost of a</p><p>fuel cell is ~$3000 per kilowatt. A UK firm ITM Power of Cambridge is</p><p>claiming that it should be able to reduce this to ~$100/kW by develop-</p><p>ing a simplified fuel cell architecture based on a patented unique</p><p>family of ionically conducting polymers which are cheap to produce.</p><p>Production costs will be considerably reduced due to its patented one-</p><p>stop manufacturing process. A complete fuel cell stack would be made</p><p>in a single process. It plans to have domestic-scale fuel cells on the</p><p>market in 2005.</p><p>Storage techniques – electricity</p><p>Flywheel technology</p><p>The use of flywheel technology to store energy has been pioneered in</p><p>vehicles. Braking energy is used to power a flywheel which then sup-</p><p>plements acceleration energy. The development thrust, however,</p><p>has come from space technology. Its true potential lies in the storage of</p><p>energy over a much longer term and in larger quantities as friction</p><p>problems are overcome. An experimental project is underway on the</p><p>Isle of Islay which is also the site of the pioneer wave energy projects</p><p>(Chapter 3).</p><p>The Japanese are taking the technology further by developing a</p><p>levitating flywheel using high temperature superconducting ceramics</p><p>to repel magnetic fields. The flywheel is made to rotate by electromag-</p><p>netic induction to a speed of 3600 revolutions per minute which repre-</p><p>sents an energy storage capacity of 10 000 watt hours. Energy can be</p><p>drawn off by the permanent magnets in the disc inducing an electric</p><p>current in a coil. If situated in a vacuum, the energy loss over a 24 hour</p><p>period would be negligible (New Scientist, 13 July 1991, p. 28).</p><p>Hydrogen storage</p><p>Hydrogen has an image problem thanks to regular replays of the</p><p>Hindenberg disaster. The traditional storage method is to contain it</p><p>in pressurised tanks (see Freiburg House, Figure 16). Up to 50 litres can</p><p>be stored at 200 to 250 bar. Larger-scale operations need pressures of</p><p>500–600 bar.</p><p>It can be liquefied, but this requires cooling to �253�C which is</p><p>highly energy intensive. In this form it has a high energy to mass ratio –</p><p>three times better than petrol but it requires heavily insulated tanks.</p><p>Bonded hydrogen is one of the more favoured options. Metal</p><p>hydrides such as FeTi compounds store hydrogen by bonding it chem-</p><p>ically to the surface of the material. The metal is charged by injecting</p><p>hydrogen at high pressure into a container filled with small particles.</p><p>ENERGY OPTIONS</p><p>169</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 169</p><p>The hydrogen bonds with the material producing heat in the process.</p><p>The hydrogen is released as the heat and pressure dissipate.</p><p>Regenerative fuel cell</p><p>A technology which is about to receive its first large-scale demonstra-</p><p>tion is based on a technology called ‘Regenesys’. It converts electrical</p><p>energy to chemical energy which is reversible and is capable of storing</p><p>massive amounts of electricity.</p><p>National Power in the UK is constructing a 360 GJ installation with</p><p>a rated power output of 15 MW which will feed directly into the grid.</p><p>In the opinion of the Royal Commission on Environmental Pollution,</p><p>hydrogen and regenerative fuel cells will be in widespread operation by</p><p>the middle of the century. If global warming and security of energy sup-</p><p>ply issues simultaneously become critical then viable large-scale storage</p><p>technologies will arrive much sooner.</p><p>Photovoltaic applications</p><p>Commercial buildings have perhaps the greatest potential for PV cells</p><p>to be integrated into their glazing as well as being roof mounted. Even</p><p>at the present state of the technology, Ove Arup and Partners estimate</p><p>that one third of the electricity needed to run an office complex could</p><p>come from PVs with only a 2 per cent addition to the building cost. The</p><p>main advantage of commercial application is that offices use most of</p><p>their energy during daylight hours. The case study of the Zicer building</p><p>in the University of East Anglia will serve as an example (Chapter 18).</p><p>One of the challenges of the next decades will be to retrofit build-</p><p>ings with PVs. A pioneer example is the Northumberland Building for</p><p>the University of Northumbria in Newcastle where cells have been</p><p>applied to the spandrels beneath the continuous windows (see Smith, P.,</p><p>and Pitts, A.C. (1997), Concepts in Practice Energy, Batsford).</p><p>Given the abundance of information and advice available, design-</p><p>ers should now be able to grasp the opportunities offered by such</p><p>technologies which also allow exploration of a range of new aesthetic</p><p>options for the building envelope.</p><p>The most extensive use of PV technology has been in the commercial</p><p>and institutional sector. Reference was made earlier to the solar offices at</p><p>Doxford with its complete southerly facade supporting 400 000 PV cells.</p><p>More recently the technology has been incorporated into an</p><p>atrium roof at Nottingham University’s Jubilee Campus (Figure 13.4).</p><p>However, much more ambitious PV programmes have been carried</p><p>out on the continent. In Chapter 11 the example of the Mont Cenis</p><p>training centre in Germany was cited as an ambitious use of PVs. It is a</p><p>multi-use complex, principally an Academy for Further Education, a</p><p>hotel, offices and a library. These are contained within a glazed envelope</p><p>180 m by 72 m and 16 m high. Of the 12 000 m2 of roof, 10 000 m2 are</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>170</p><p>AIAC-Ch13.qxd 03/25/2005 17:25 Page 170</p><p>ENERGY OPTIONS</p><p>171</p><p>devoted to PV cells producing more than twice the energy demand of</p><p>the building (Figure 13.5).</p><p>The PV market is growing dramatically – 43.8 per cent in 2002</p><p>with most going to grid connected supply in Japan, Germany and</p><p>California. This is a technology which is seen to have enormous potential</p><p>and therefore is attracting considerable research effort. The Sunpower</p><p>Corporation is manufacturing a solar cell which achieves an efficiency of</p><p>over 20 per cent as verified by the US National Renewable Energy</p><p>Laboratory. This laboratory has also verified the bench efficiency of</p><p>36.9 per cent achieved by Spectrolab’s Improved Triple Junction solar</p><p>cell. Efficiencies of over 40 per cent are confidently predicted. As</p><p>economies of scale also bring down costs, the impact on the electricity</p><p>market could be dramatic with the potential for every home to become a</p><p>micro-power station. Before these developments had occurred, Hermann</p><p>Scheer calculated that Germany’s aggregate demand of 500 TWh/year</p><p>could be met by installing PVs on 10 per cent of roofs, facades and motor-</p><p>way sound barriers (The Solar Economy, p. 64, Earthscan 1999).</p><p>Heat pumps</p><p>Heat pumps are an offshoot of refrigeration technology and are capable</p><p>of providing both heat and cooling. They exploit the principle that</p><p>Figure 13.4</p><p>Photovoltaic cells, Jubilee Campus,</p><p>Nottingham University</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 171</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>172</p><p>certain chemicals absorb heat when they are condensed into a liquid</p><p>and release heat when they evaporate into a gas.</p><p>There are several different refrigerants that can be used for space</p><p>heating and cooling with widely varying global warming potential (GWP).</p><p>Refrigerants which have an ozone depleting potential are now banned.</p><p>Currently refrigerants which have virtually zero GWP on release include</p><p>ammonia which is one of the most prevalent.</p><p>The heating and cooling capacity of the refrigerant is enhanced by</p><p>the extraction of warmth or cooling from an external medium – earth,</p><p>air or water.</p><p>The most efficient is the ground source heat pump (GSHP) which</p><p>originated in the 1940s. This is another technology which goes back a</p><p>long way but which is only now realising its potential as a technology for</p><p>the future.</p><p>It exploits the stable temperature of the earth for both heating and</p><p>cooling. The principle of the GHP is that it does not create heat; it trans-</p><p>ports it from one area to another. The main benefit of this technology is</p><p>that it uses up to 50 per cent less electricity than conventional electrical</p><p>heating or cooling.</p><p>At present ground coupled heat pumps have a coefficient of per-</p><p>formance (COP) between 3 and 4 which means that for every kilowatt of</p><p>electricity they produce 3 to 4 kilowatts of useful heat. The theoretical</p><p>ultimate COP for heat pumps is 14. In the near future a COP of 6 is likely.</p><p>Figure 13.5</p><p>PV roof over the Mont Cenis complex,</p><p>Herne Sodingen, Germany</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 172</p><p>Most ground coupled heat pumps adopt the closed loop system</p><p>whereby a high density polyethylene pipe filled with a mix of water and</p><p>antifreeze, which acts as a heat transporter, is buried in the ground. It is</p><p>laid in a U configuration vertically and a loop horizontally. The vertical</p><p>pipes descend up to a 100 m depth; the horizontal loop is laid at a min-</p><p>imum of 2 m depth.</p><p>The horizontal type is most common in residential situations where</p><p>there is usually adequate open space and because it incurs a much</p><p>lower excavation cost than the alternative. The only problem is that,</p><p>even at a 2 m depth, the circuit can be affected by solar gain or</p><p>rainfall evaporation. In each case the presence of moving ground water</p><p>improves performance.</p><p>Usually the lowest cost option is to use water in a pond, lake or</p><p>river as the heat transfer medium. The supply pipe is run underground</p><p>from the building and coiled into circles at least 2 m below the surface.</p><p>Heat pumps have been compared to rechargeable batteries that</p><p>are permanently connected to a trickle charger. The battery is the</p><p>ground loop array which has to be large enough, together with a</p><p>matched compressor, to meet the heating/cooling load of a building.</p><p>The energy trickle comes from the surrounding land which recharges</p><p>the volume of ground immediately surrounding the loop. If the energy</p><p>removed from the ground exceeds the ground’s regeneration capacity,</p><p>the system ceases to function, so it is essential that demand is matched</p><p>to the ground capacity (from Dr Robin Curtis, GeoScience Ltd).</p><p>Pencoys Primary School in Cornwall is an example of a PFI project</p><p>by W.S. Atkins which supplements its energy with GS heat pumps. The</p><p>system has 15 shafts sunk to a depth of 45 m. The heat pumps produce</p><p>water at 45–50�C which is stored in two 700 litre insulated buffer tanks.</p><p>A secondary circuit serves to provide underfloor heating at about 50�C.</p><p>The system has a coefficient of performance of 4. The heat pumps oper-</p><p>ate mainly at night using off-peak electricity to minimise costs. The</p><p>stored heat together with internal heat gains and the thermal mass of</p><p>the building provide space heating for most of the time. In really cold</p><p>weather immersion heaters in the storage vessels boost heat output.</p><p>At current energy prices the system is more expensive to run</p><p>than a conventional boiler installation. However, gas prices will proba-</p><p>bly continue to rise due to security of supply problems. This, plus the</p><p>climate change levy, will enable the system to overtake a standard</p><p>boiler option in economy of running costs in the near future. The sys-</p><p>tem was designed by GeoScience.</p><p>GeoScience was also involved in the design of one of the first busi-</p><p>ness parks in the UK to exploit this technology, namely the Tolvaddon</p><p>Energy Park in Cornwall which exploits geothermal energy with 19 heat</p><p>pumps that pump water around boreholes to a depth of 70 metres. This</p><p>project was only made viable because of support from the Regional</p><p>Development Agency (RDA) for the South West which required that this</p><p>business park should be a demonstration of heat pump technology.</p><p>ENERGY OPTIONS</p><p>173</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 173</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>174</p><p>Where buildings require piled foundations, an economical option</p><p>is to integrate ground source heat pumps into the foundations as</p><p>demonstrated by the ‘Building of the Future’, Primrose Hill, London, by</p><p>Richard Paxton Architects (Figure 13.6). This is a mixed office and resi-</p><p>dential development totalling 1000 m2. The GS heat pumps utilise four</p><p>plastic pipe loops connected to the reinforcement steel of the piles.</p><p>These supply both heating and cooling to the floors depending on the</p><p>season. A secondary coil is positioned in the roof and linked to the cen-</p><p>tral manifold. This supplements the heating when necessary but also</p><p>serves as a night cooling system by dumping heat in summer. A gas</p><p>boiler and evaporative (adiabatic) mechanical cooling act as backup to</p><p>the heat pumps.</p><p>In addition, PVs on the roof meet most of the electricity needs of</p><p>the building. In all it is expected that energy costs compared with con-</p><p>ventional heating and cooling will be reduced by about 30 per cent</p><p>(Figure 13.6).</p><p>Energy storage – heating and cooling</p><p>Sources of natural energy are intermittent. To obtain continuous flows</p><p>of energy using such sources therefore requires systems of storage. As</p><p>stated earlier, this is not a new concept since, in the Middle Ages, tide</p><p>Figure 13.6</p><p>Building of the Future, London</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 174</p><p>mills stored water at high tide in order to release it at an appropriate</p><p>rate to turn the water wheel during the ebb tide.</p><p>Energy storage offers an efficiency and cost gain in two respects.</p><p>First, in buildings that optimise solar gain, surplus solar energy can be</p><p>used to charge a storage facility to be used later for space heating.</p><p>Second, storage can help to flatten the peaks of electricity costs by</p><p>charging the store with off-peak electricity and using the stored power</p><p>to reduce demand at peak periods.</p><p>The storage potential of energy is available for three purposes:</p><p>heating, cooling and the storage of electricity.</p><p>Heat storage</p><p>The most straightforward method of storage is by means of a network</p><p>of pipes carrying solar heated air though a reasonably dense medium</p><p>such as bricks, concrete blocks or water. The storage container is heavily</p><p>insulated. If sufficient space is available below a building, enough heat</p><p>can be stored to supplement space heating through the whole of</p><p>the heating season, hence the term ‘seasonal storage’. Alternatively,</p><p>off-peak or PV derived electricity may be used as the heating element.</p><p>More sophisticated is the use of a phase change material such as</p><p>sodium sulphate which works on the principle of the latent heat of</p><p>fusion. Called eutectic or ‘Glaubars’ salts this medium turns from solid</p><p>to liquid at around 30�C and then gives off heat as it solidifies.</p><p>Cool storage</p><p>As the automatic inclusion of full air conditioning is increasingly being</p><p>questioned, the problem of space cooling enters a new dimension.</p><p>Again the principle is to use spare energy, off-peak or PV electricity, to</p><p>refrigerate a medium. At its crudest, the medium may be the earth</p><p>beneath a building. A more practicable method is to use phase change</p><p>and the latent heat of fusion as above to provide high density storage.</p><p>One option called the STL storage system comprises a storage ves-</p><p>sel containing spherical polyethylene nodules filled with a solution of</p><p>eutectic salts and hydrates. This system is ideal in situations where</p><p>there is cyclic demand since it facilitates cooling (or heating) when</p><p>energy costs are at their lowest or a plant is shut down. In conjunction</p><p>with air conditioning, this system can result in a dramatic lowering of</p><p>the required capacity of the chiller unit. The system may be given a lift</p><p>in efficiency by the use of heat pumps which provide either cooling or</p><p>warmth on the principle of a refrigerator.</p><p>As indicated earlier, the building fabric can be a significant energy</p><p>storage system on the basis of thermal mass. Heat absorbed by the</p><p>structure flattens the peaks and troughs of temperature. Exposed con-</p><p>crete floors have been cited as an efficient storage medium for convec-</p><p>tive and radiative heat transfer. It is worth noting again that it is the</p><p>ENERGY OPTIONS</p><p>175</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 175</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>176</p><p>outer 100 mm of the fabric which comprise the effective thermal mass.</p><p>The effectiveness of the underside of the floor is negated by sus-</p><p>pended ceilings. However, a compromise solution is perforated tiles</p><p>which have an open area of 42 per cent which is sufficient to allow</p><p>91.6 per cent overall heat transfer whilst concealing services.</p><p>Seasonal energy storage</p><p>A marriage between solar energy and the thermal constancy of the</p><p>ground offers an opportunity to make significant reductions in both the</p><p>heating and cooling loads generated by buildings. Known as ‘aquifer</p><p>storage’ the principle is that, in summer, buildings absorb considerable</p><p>amounts of surplus heat which can either be vented to the atmosphere</p><p>or used to provide a reservoir of warmth for the winter. The energy stor-</p><p>age system comprises two wells drilled into the water table below the</p><p>building, one warm the other cold. The system relies on the fact that</p><p>ground water is a constant (10–12�C in the UK).</p><p>This system should be distinguished from the tanked seasonal stor-</p><p>age at Frierichshafen described earlier which is fed by solar thermal panels.</p><p>In summer water from the cold well is pumped into the building and,</p><p>via a heat exchanger, cools the ventilation system. As it passes through</p><p>the building it absorbs heat ending up at around 15–20�C. It is then</p><p>returned to the warm well. In winter the system is reversed and warm</p><p>water heats the ventilation air. It loses heat to the building and returns to</p><p>the cold well at about 8�C to be stored for summer cooling (Figure 13.7).</p><p>Figure 13.7</p><p>Principles of seasonal storage</p><p>(courtesy of CADDET)</p><p>Summer</p><p>Basic functioning of energy storage in aquifers.</p><p>Cold circuit</p><p>Aquifer Aquifer</p><p>Warm</p><p>well</p><p>15–20°</p><p>Warm</p><p>well10°C</p><p>Cold</p><p>well</p><p>Winter</p><p>Heat Exchanger Heat Exchanger</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 176</p><p>ENERGY OPTIONS</p><p>177</p><p>The Netherlands are leading the way in this technology with</p><p>19 projects completed or under way with a projected annual primary</p><p>energy saving of 1.5 million cubic metres of natural gas equivalent.</p><p>Recent buildings to benefit from this technology include the Reichstag</p><p>in Berlin and the city hall and Schiphol Airport offices in The Hague.</p><p>In the case of the Reichstag surplus heat is stored interseasonally in</p><p>a natural aquifer 400 m below ground. Aquifers at 40 m depth are used</p><p>for cooling.</p><p>The Sainsbury supermarket at Greenwhich Peninsular, completed</p><p>in September 1999, employs earth sheltered walls to regulate tempera-</p><p>ture on the sales floor. Ventilation air is passed through underground</p><p>ducts to maintain cooling. Also there are two 75 m deep boreholes,</p><p>one absorbing heat from refrigeration equipment, the other providing</p><p>ground cooling.</p><p>Electricity storage</p><p>Batteries</p><p>Battery technology is still the most common method of storage, but the</p><p>promised breakthrough in this technology has yet to materialise. Still in</p><p>general use is the traditional lead acid battery which is heavy, expensive</p><p>and of limited life. Even the ground-breaking Freiburg zero electric</p><p>house</p><p>to be</p><p>combined with passive cooling systems to provide a greener and more</p><p>cost-effective solution’ (Jake Hacker, project leader for the research).</p><p>Such mixed mode solutions are the way for the future.</p><p>The report makes the sobering remark that even the BRE low</p><p>energy office in Watford fails to meet BRE’s own benchmark for comfort</p><p>from 2020 onwards.</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>180</p><p>AIAC-Ch13.qxd 03/25/2005 17:26 Page 180</p><p>181</p><p>Chapter</p><p>Fourteen</p><p>Lighting – designing for</p><p>daylight</p><p>As one of the largest energy sinks for commercial and industrial buildings,</p><p>lighting justifies special treatment. Furthermore, with buildings becom-</p><p>ing increasingly energy efficient in terms of space heating so the light-</p><p>ing load becomes of greater significant. It will be some time before we</p><p>realise the revolution in lighting promised by developments in light</p><p>emitting diodes.</p><p>Current wisdom has it that office design should optimise natural</p><p>lighting. One reason for this is that lighting is often the largest single</p><p>item of energy cost, particularly in open plan offices. Another factor is</p><p>that occupants tend to prefer natural light, especially since certain</p><p>forms of artificial lighting have been implicated as the source of health</p><p>problems.</p><p>Energy efficient buildings should make as much beneficial use of</p><p>naturally available light as possible. Lighting is important because of</p><p>the influence it has over occupant experience. Until about 50 years ago,</p><p>the use of windows and plan form of buildings was very much influ-</p><p>enced by the limits of natural light admission. The development of the</p><p>fluorescent tube lamp made the deep plan office a feasible proposition</p><p>but at the expense of noise pollution and frequency band discomfort.</p><p>There was the added psychological penalty of reducing access to day-</p><p>light and external views. It is only relatively recently that the importance</p><p>of these benefits have been acknowledged.</p><p>Principal factors influencing levels of daylight are:</p><p>● orientation of windows;</p><p>● angle of tilt of windows;</p><p>● obstructions to light admission (e.g. nearby buildings);</p><p>● reflectivity of surrounding surfaces.</p><p>Factors which relate to the exploitation of daylight include:</p><p>● Windows provide external views and time orientation for occupants.</p><p>● Occupants are more accepting of variable illumination when day-</p><p>light is the light source.</p><p>● Natural light produces a true colour rendering.</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 181</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>182</p><p>However, it would be unusual to expect to supply all lighting requirements</p><p>using daylight in non-domestic buildings.</p><p>Design considerations</p><p>In order to achieve successful daylighting design, the following aspects</p><p>should be considered:</p><p>● The amount of glazing has a clear influence on the amount of</p><p>daylight available, but more window area is not always better, it may</p><p>simply increase contrast.</p><p>● Large windows admit light but also provide heat gain and heat loss</p><p>routes and thus potential thermal discomfort, especially from cold</p><p>draughts near the windows.</p><p>● Allocation of rooms to facades should be appropriate to the activity –</p><p>to do this successfully will require consideration of the issues at the</p><p>building planning stage.</p><p>● The amount of sky which can be seen from the interior is a critical</p><p>factor in determining satisfactory daylighting.</p><p>● High window heads permit higher lighting input as more sky is</p><p>visible.</p><p>● External obstructions/buildings which subtend an angle of less than</p><p>25� to the horizontal will not usually exclude use of natural daylight.</p><p>● If there are many external obstructions the room depth should be</p><p>reduced.</p><p>● Daylight normally penetrates about 4–6 m from the window into</p><p>the room.</p><p>● Adequate daylight levels can be achieved up to a depth of about</p><p>2.5 times the window head height.</p><p>● Rooflights give a wider and more even distribution of light but also</p><p>permit heat gains which may cause overheating.</p><p>● Generally rooflights provide about three times the benefit of an</p><p>equivalently sized vertical window.</p><p>● Rooflight spacing should be one to one-and-a-half times the ceiling</p><p>height.</p><p>● Where single sided daylighting is proposed, the following formula</p><p>gives a limiting depth (L) to the room:</p><p>(L/W ) � (L/H) �� 2/(1 - Rb)</p><p>where L � room depth, m</p><p>W � room width, m</p><p>H � height of top of window, m</p><p>Rb � average reflectance of internal surfaces</p><p>(Adrian Pitts in Smith, P. and Pitts, A.C. (1997) Concepts in Practice –</p><p>Energy, Batsford).</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 182</p><p>LIGHTING – DESIGNING FOR DAYLIGHT</p><p>183</p><p>● In non-domestic buildings, the window area should be about</p><p>20 per cent of the floor area to provide sufficient light to a depth of</p><p>about 1.5 times the height of the room.</p><p>● Internal reflectances should be kept as high as possible.</p><p>Examples</p><p>One of the most dramatic techniques for channelling daylight into the</p><p>deep interior of a building has been devised by Foster Associates for</p><p>the Reichstag building.</p><p>The original design was for an all encompassing canopy but this</p><p>proved much too expensive. Initially Norman Foster opposed the idea of</p><p>reinstating a dome since this was emblematic of an era best forgotten.</p><p>However, he yielded to pressure and used the dome as an opportunity to</p><p>create something dramatic.</p><p>It is effectively a double dome, with the lower portion sealed from</p><p>the upper space (echoes of Wren at St Paul’s Cathedral). The upper</p><p>cupola is a public space which permits views into the chamber. The</p><p>spectacular feature is the cone designed by Claude Engel which is</p><p>sheathed in 360 mirrors that reflect daylight into the lower chamber.</p><p>Sun-tracking shading prevents direct sunlight from reaching the cham-</p><p>ber. The cone houses air extract and heat exchange equipment. The</p><p>motorised shading and the heat exchange equipment is powered by</p><p>photovoltaics (Figure 14.1).</p><p>Figure 14.1</p><p>Reflective cone in the Reichstag</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 183</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>184</p><p>The atrium</p><p>The atrium has become an almost universal feature of commercial</p><p>buildings. Occasionally the incorporation of an atrium can transform</p><p>existing buildings, as in the case of the city campus of Sheffield Hallam</p><p>University (Figure 14.2). There is no doubt that much of the appeal of</p><p>atria lies in their aesthetic attributes. However, they have a practical</p><p>justification by creating opportunities for introducing natural light and</p><p>ventilation often deep into a building.</p><p>The shape and form of the atrium also has an important effect on</p><p>the availability of natural lighting in the spaces adjacent to the atrium.</p><p>There are several factors to consider.</p><p>● The structure of the atrium roof can reduce its transparency by</p><p>between 20 and 50 per cent. This is an important factor if the ground</p><p>level is meant to be predominantly naturally lit.</p><p>● The offices enclosing the atrium will benefit from a measure of natural</p><p>light as well as external views. Access to natural light will be improved</p><p>significantly if the sides of the atrium are stepped outwards.</p><p>Figure 14.2</p><p>Atrium between existing buildings,</p><p>Sheffield Hallam University</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 184</p><p>LIGHTING – DESIGNING FOR DAYLIGHT</p><p>185</p><p>● The surface finish in respect of colour and reflectance of the atrium</p><p>walls will influence the level of daylight reaching the lower floors.</p><p>Light shelves</p><p>Light shelves have been in use for some time and serve the dual</p><p>purpose of providing shade and reflected light. Sunlight is reflected from</p><p>the upper surface of the light shelf into the room interior and particu-</p><p>larly onto the ceiling where it provides additional diffuse light thus help-</p><p>ing to provide uniform illumination. Under conditions of an overcast</p><p>sky, light shelves cannot increase the lighting level. They operate most</p><p>effectively in sunlight. In this context ceilings are usually designed to be</p><p>higher than normal for best operation (Figure 14.3).</p><p>Some degree of control is possible by modifying the angle of the</p><p>light shelf; either internally or externally or in combination. Problems</p><p>with</p><p>low angle winter sunlight penetration can give rise to glare. Difficulties can</p><p>be experience in cleaning the light shelves, especially the external type.</p><p>Earlier, Portcullis House illustrated this feature with a level of</p><p>sophistication involving a corrugated reflective surface to maximise</p><p>high altitude reflection whilst rejecting low altitude short wave solar</p><p>radiation. This almost doubles the daylight levels in north facing rooms.</p><p>Prismatic glazing</p><p>Whilst the systems so far discussed rely on the reflection of light, prismatic</p><p>glazing operates by refracting incoming light. The system consists of a</p><p>panel of linear prisms (triangular wedges) which refract and spread the</p><p>incoming light to produce a more diffuse distribution. The view out is sub-</p><p>stantially restricted, but the system can be used as an alternative to the</p><p>reflective louvre system without some of its drawbacks. Glare can be</p><p>somewhat reduced too. Maintenance is virtually eliminated if the system</p><p>is installed between the panes of double glazed units.</p><p>Light pipes</p><p>Light pipes gather incoming sunlight sometimes using a solar tracking</p><p>system. The light is concentrated using lenses or mirrors and is then</p><p>transmitted to building interiors by ‘pipes’. The pipes can be hollow</p><p>shafts or ducts with reflective internal finishes, or may use fibre optic</p><p>cable technology. A special luminaire is required to provide distribution</p><p>of the light within the building.</p><p>The system is heavily reliant on the availability of sunlight and for</p><p>critical tasks or areas a backup artificial light source is required.</p><p>Examples of the technology are to be found in the roof of the</p><p>concourse at Manchester Airport, UK, and the experimental low energy</p><p>house at Nottingham University (Figure 14.4).</p><p>Figure 14.3</p><p>Basic principle of the light shelf</p><p>Figure 14.4</p><p>Section through a sunpipe</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 185</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>186</p><p>Figure 14.5</p><p>Solar shading, Wessex Water Divisional</p><p>Headquarters</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 186</p><p>LIGHTING – DESIGNING FOR DAYLIGHT</p><p>187</p><p>Holographic glazing</p><p>Holographic glazing is still under development but potentially offers</p><p>advantages over prismatic glazing. A diffraction process is also used,</p><p>but in this case the light output can be more finely tuned to produce</p><p>particular internal light patterns. There are some limitations set by the</p><p>angle of incoming light to which the holographic pattern is tuned.</p><p>Solar shading</p><p>In considering climate facades solar shading featured as an integral ele-</p><p>ment in the triple glazing. More common are external shading devices</p><p>which are confined to the southerly elevation. These are featured in</p><p>Portcullis House. More recently the Wessex Water building features</p><p>some of the most complex solar shading devices yet encountered</p><p>(Figure 14.5).</p><p>The Millennium Galleries opened in Sheffield in 2001 have some of</p><p>the most elaborate solar shading which can be rotated through 90� to</p><p>achieve levels of solar exclusion up to total internal blackout (Figure 14.6).</p><p>Figure 14.6</p><p>Variable solar shading, Millennium</p><p>Galleries, Sheffield</p><p>AIAC-Ch14.qxd 03/25/2005 17:27 Page 187</p><p>188</p><p>Chapter</p><p>Fifteen</p><p>Lighting – and human</p><p>failings</p><p>Artificial lighting is a major factor in deciding the quality of the internal</p><p>environment of offices. It is also a serious contributor to carbon dioxide,</p><p>(CO2) emissions accounting in the US, for example, for up to 30 per cent</p><p>of total electricity use (Scientific American, March 2001). For these reasons</p><p>it is a subject that warrants special attention.</p><p>Design studies suggest that considerable energy savings can be</p><p>made by maximising natural light, particularly if it is linked to automatic</p><p>controls. Passive solar studies claim that efficient and well-controlled</p><p>lighting would reduce energy/carbon dioxide costs by more than any</p><p>other single item.</p><p>There is still reluctance to accept any additional capital cost to</p><p>achieve sustainable design despite the prospect of significant revenue</p><p>savings. Even in terms of capital cost alone energy efficiency can make</p><p>savings. For example, high frequency lighting, good reflecting lumi-</p><p>naires and infra-red controls can save money because fewer fittings are</p><p>required with lower heat production, in turn leading to a reduced cool-</p><p>ing load. At the same time there is the chance to install fewer switch</p><p>drops reducing cabling and simplifying fitting-out. This lighting strat-</p><p>egy could also reduce the contract period with obvious benefits in</p><p>terms of an earlier occupancy date.</p><p>Post-occupancy analysis has thrown some doubt on these assump-</p><p>tions (Bordass, W., PROBE studies). Changes in office design and work</p><p>routines has caused a reappraisal of the maximisation philosophy. In</p><p>addition, a build-up of user appraisal has shown that, in many cases,</p><p>the claimed benefits of maximising natural lighting have turned into</p><p>clear dis-benefits. As a result, recent occupancy studies have shown</p><p>that artificial lights are left on much more than predicted. There are</p><p>many reasons for this, and this chapter will review some of the most</p><p>prominent.</p><p>When the original research into alternatives to the permanently</p><p>artificially lit office space was carried out, work in offices was largely</p><p>paper based. At the same time, research and guidance in the past has</p><p>been simplistic and inadequately focused on the real contexts in</p><p>which people make decisions. For example, it is possible for a single</p><p>AIAC-Ch15.qxd 03/25/2005 17:28 Page 188</p><p>LIGHTING – AND HUMAN FAILINGS</p><p>189</p><p>decision by an individual to put a whole system into an energy wasting</p><p>state. Insufficient consideration is given to the fact that anomalous</p><p>situations are often difficult to correct and it is easier to adopt the ‘inertia</p><p>solution’.</p><p>Now computers are the universal office tool and excessive daylight</p><p>can be a severe nuisance due to reflection from VDU screens. If lighting</p><p>controls are not tuned to each individual workstation, this can result in</p><p>greater energy use than in a conventional office. For example, it has</p><p>been found that all lights can be on because one person has drawn the</p><p>blinds to avoid glare. Even where lights are zoned according to daylight</p><p>penetration, these often do not relate to workstations with the result</p><p>that lights are on all day to compensate.</p><p>A lesson which is being gradually learnt is that individuals will</p><p>always select the least cost option in terms of effort. It is not that peo-</p><p>ple are inherently lazy, but that they will tend to resent expending effort</p><p>on activities which they regard as the responsibility of management.</p><p>For example, it is often easier to switch on lights than adjust blinds, and</p><p>that is what happens when natural light levels fluctuate. The common</p><p>‘inertia response’ is to close the blinds and switch on the lights. Where</p><p>daylight results in glare, individuals will adjust the blinds and artificial</p><p>lighting to avoid discomfort and achieve an even distribution of lighting</p><p>regardless of energy consumption.</p><p>In cellular offices individuals take more responsibility for adjusting</p><p>their light levels and optimising the relationship between artificial and</p><p>natural lighting. In open plan situations where no individual is responsible,</p><p>blinds tend to be left closed if that was their position on the previous day,</p><p>regardless of external conditions.</p><p>Photoelectric control</p><p>Where lights are operated electronically according to natural light lev-</p><p>els, the systems can be either closed or open loop. A closed loop sys-</p><p>tem controls the lighting to top up the daylight to achieve a given</p><p>minimum acceptable illuminance level. Open systems measure exter-</p><p>nal incident daylight to dim lights but with no feedback of the actual</p><p>levels of realised illuminance.</p><p>Blinds can override the controls of both open and closed systems.</p><p>Complaints at the lack of finesse of such systems can result in manage-</p><p>ment abandoning photoelectric control altogether. Where sensors in</p><p>closed systems are near windows, it is not uncommon to find occupants</p><p>closing the blinds to activate the lights.</p><p>are leading, on the one hand, to increased</p><p>area of desert, and, on the other, greater intensity of rain storms</p><p>which increase run-off and erosion of fertile land. In both cases</p><p>there is a loss of carbon fixing greenery and food producing land.</p><p>● In the first months of 2000 Mozambique experienced catastrophic</p><p>floods which were repeated in 2001. In 2002 devastating floods</p><p>occurred across Europe inundating historic cities like Prague and</p><p>Dresden creating ‘one of the worst flood catastrophes since the</p><p>Middle Ages’ (Philippe Busquin, European Union Research</p><p>Commissioner). The following year saw a similar occurrence with</p><p>the rivers Elbe and Rhone bursting their banks.</p><p>● In July 2004 Southeast Asia experienced catastrophic floods due to</p><p>exceptional rainfall, rendering 30 million homeless in Bangladesh</p><p>and the Indian state of Bihar. At the same time central China also</p><p>CLIMATE CHANGE – NATURE OR HUMAN NATURE?</p><p>7</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 7</p><p>suffered devastating floods whilst Delhi experienced a major</p><p>draught. The people of Ethiopia are facing starvation in their</p><p>millions because of the year-by-year failure of the rains.</p><p>● Insurance companies are good barometers of change. One of the</p><p>largest, Munich Re, states that claims due to storms have doubled</p><p>in every decade since 1960. In that decade there were 16 disasters</p><p>costing £30 billion. In the last decade of the century there were 70</p><p>disasters costing £250 billion. In the first years of this century the</p><p>pace has quickened. Munich Re has reported that the 700 natural</p><p>disasters in 2003 claimed 50 000 lives and cost the insurers £33 billion.</p><p>The Loss Prevention Council has stated that, by the middle of this</p><p>century, losses will be ‘unimaginable’. Yet, these extreme climatic</p><p>events are only part of the scenario of global warming.</p><p>● Besides the effect of increasingly steep pressure gradients another</p><p>factor contributing to the intensification of storms is the contraction</p><p>of snow fields. These have in the past created high pressure zones</p><p>of cold stable air which have kept at bay the Atlantic lows with their</p><p>attendant storms. This barrier has weakened and shifted further</p><p>east allowing the storms to reach western Europe. The increased</p><p>frequency of storms and floods in this area during the last decade of</p><p>the twentieth century adds weight to this conclusion.</p><p>● El Niño has produced unprecedentedly severe effects due to the</p><p>warming of the Pacific. There is even talk that the El Niño reversal</p><p>may become a fixture which would have dire consequences for</p><p>Australia and Southeast Asia.</p><p>● Receding polar ice is resulting in the rapid expansion of flora;</p><p>Antarctic summers have lengthened by up to 50 per cent since the</p><p>1970s and new species of plants have appeared as glaciers have</p><p>retreated. In Iceland Europe’s largest glacier is breaking up and is</p><p>likely to slide into the north Atlantic within the next few years, high-</p><p>lighting the threat to sea levels from land-based ice (The Observer,</p><p>22 October 2000). The Arctic ice sheet has thinned by 40 per cent</p><p>due to global warming (report by an international panel of climate</p><p>scientists, January 2001).</p><p>● Sea level has risen 250 mm (10 inches) since 1860. Up to now much</p><p>of the sea level rise has been due to thermal expansion.</p><p>● Sea temperatures in Antarctica are rising at five times the global</p><p>average, at present a 2.5�C increase since the 1940s. The major</p><p>threat lies with the potential break-up of land-based ice. The recent</p><p>breakaway of the 12 000 sq. km of the Larson B ice shelf has serious</p><p>implications. In itself it will not contribute to rising sea levels. The</p><p>danger lies in the fact that the ice shelves act as a bulwark support-</p><p>ing the land-based ice. In the May 2003 edition of Scientific</p><p>American it was reported that, following the collapse of the Larson</p><p>ice shelf ‘inland [land based] glaciers have surged dramatically</p><p>towards the coast in recent years’. Satellite measurements have</p><p>shown that the two main glaciers have advanced 1.25 and 1.65 km</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>8</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 8</p><p>respectively. That represents a rate of 1.8 and 2.4 metres per day.</p><p>When the West Antarctic ice sheet totally collapses, as it will, this</p><p>will raise sea level by 5 m (Scientific American, op. cit., p. 22). In</p><p>April 1999 The Guardian reported that this ice shelf was breaking</p><p>up 15 times faster than predicted. Even more disconcerting is the</p><p>fact that the largest glacier in Antarctica, the Pine Island glacier, is</p><p>rapidly thinning – 10 metres in eight years – and accelerating</p><p>towards the sea at a rate of 8 metres a day. This is another indica-</p><p>tion of the instability of the West Antarctic ice sheet.</p><p>● At the same time there has been massive melting of glacier ice on</p><p>mountains. The Alps have lost 50 per cent of their ice in the past</p><p>century. The International Commission on Snow and Ice has</p><p>reported that glaciers in the Himalayas are receding faster than</p><p>anywhere else on Earth.</p><p>● In Alaska there is general thinning and retreating of sea ice, drying</p><p>tundra, increasing storm intensity, reducing summer rainfall, warmer</p><p>winters and changes in the distribution, migration patterns and</p><p>numbers of some wildlife species. Together these pose serious</p><p>threats to the survival of the subsistence-indigenous Eskimos</p><p>(New Scientist, 14 November 1998).</p><p>● From Alaska to Siberia, serious infrastructure problems are occur-</p><p>ring due to the melting of the permafrost. Roads are splitting apart,</p><p>trees keeling over, houses subsiding and world famous ski resorts</p><p>becoming non-viable. In Alaska and much of the Arctic tempera-</p><p>tures are rising ten times faster than the global average – 4.4�C in</p><p>30 years. This may, in part, be due to the melting of the snow fields</p><p>exposing tundra. Whilst snow reflects much of the solar radiation</p><p>back into space, the bare tundra absorbs heat, at the same time</p><p>releasing huge amounts of carbon dioxide into the atmosphere – a</p><p>classic positive feedback situation. The village of Shishmaref on an</p><p>island on the edge of the Arctic Circle is said to be ‘the most</p><p>extreme example of global warming on the planet’ and ‘is literally</p><p>being swallowed by the sea’. Some houses have already fallen into</p><p>the sea; others are crumbling due to the melting of the permafrost</p><p>supporting their foundations. The sea is moving inland at the rate of</p><p>3 m a year (BBC News, 23 July 2004).</p><p>● Global mean surface air temperature has increased between 0.3</p><p>and 0.6�C since the later nineteenth century. The average global</p><p>surface temperature in 1998 set a new record surpassing the previ-</p><p>ous record in 1995 by 0.2�C – the largest jump ever recorded</p><p>(Worldwatch Institute in Scientific American, March 1999). The</p><p>warmest year on record was 1999. Global warming is increasing at</p><p>a faster rate than predicted by the UN IPCC scientists in 1995. They</p><p>anticipated that temperatures would rise between 1 and 3.5�C in</p><p>the twenty-first century. According to the Director of the US National</p><p>Climate Data Center, in only a short time the rate of warming is</p><p>already equivalent to a 3�C rise per century. This makes it probable</p><p>CLIMATE CHANGE – NATURE OR HUMAN NATURE?</p><p>9</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 9</p><p>that the end of century temperature level will be significantly</p><p>higher than the IPCC top estimate (Geophysical Research Letters,</p><p>vol. 27, p. 719).</p><p>● NASA scientists report satellite evidence of the Greenland land-</p><p>based ice sheet thinning by 1 m per year. Altogether it has lost 5 m</p><p>in southwest and east coasts. On the one hand, this threatens the</p><p>Gulf Stream or deep ocean pump and on the other, it leads directly</p><p>to a rise in sea level, threatening coastal regions (Nature, 5 March</p><p>1999). Over the past 20 years the polar ice cap has thinned by</p><p>40 per cent.</p><p>● Concentrations of CO2 in the atmosphere are increasing at a steep</p><p>rate. The pre-industrial level was 590 billion tonnes or 270 parts per</p><p>million by volume (ppmv); now it is 760 billion tonnes or around 380</p><p>ppmv and rising 1.5–2 ppmv per year. Most of the increase has</p><p>occurred over the</p><p>Furthermore, in many cases</p><p>there are not enough sensors and lighting zones to take account of</p><p>localised variations in daylight due to orientation or shading. As a rule of</p><p>thumb, to avoid the need to make small-scale adjustments, lights should</p><p>not go off until the illuminance level is about twice the design level.</p><p>AIAC-Ch15.qxd 03/25/2005 17:28 Page 189</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>190</p><p>Glare</p><p>Another rule of thumb which is observed by designers is that ‘if you</p><p>can’t see the sky the daylight level is inadequate’. The result is tall win-</p><p>dows to give maximum daylight penetration. This carries the attendant</p><p>risk of glare unless workstations are properly positioned in relation to</p><p>the window. In most cases this will mean desks at right angles to the</p><p>external wall and the VDU viewing axis parallel to the window plane.</p><p>One option is to resort to automatic blinds. Occupiers sometimes</p><p>complain that the spontaneous action of the blind is an irritant and</p><p>represents a denial of individual choice. Local manual override is the</p><p>preferred answer.</p><p>Recent developments in glass technology referred to earlier in</p><p>terms of electrochromic glass offer solutions to these problems, espe-</p><p>cially if it can be controlled on an individual pane basis.</p><p>Another problem that occurs is that lighting and blinds controls are</p><p>not co-ordinated. Lights tend to stay on regardless of the position of</p><p>the blinds. The operation of externally positioned blinds can be frus-</p><p>trated by adverse weather conditions, especially high winds.</p><p>Dimming control and occupancy sensing</p><p>Closed loop systems are designed to provide a constant level of desk-</p><p>top illuminance. However, as the level of outside light fluctuates, so</p><p>individuals may wish to vary desktop light levels to minimise contrast.</p><p>On a bright day a constantly lit desk would appear gloomy.</p><p>There are obvious advantages to light switching which is respon-</p><p>sive to a human presence, but even this technology is not devoid of</p><p>problems. The adjustment of the sensors is a matter of fine tuning. For</p><p>example, they may not be sufficiently sensitive to the movements of</p><p>people engaged in high concentration tasks. Alternatively they may be</p><p>so sensitive that passers-by trigger the switch causing a distraction. In</p><p>practice it is often difficult to locate sensors to suit occupancy patterns</p><p>and work requirements especially in open plan offices where worksta-</p><p>tions may frequently be relocated. The ideal solution is to rely on manual</p><p>switching for the ‘on’ and automatic switching for the ‘off’.</p><p>Occupancy sensors achieve their optimum value in service areas</p><p>and circulation spaces. These are areas which are frequently over-</p><p>looked yet they can use more energy pro rata than office spaces. One</p><p>common fault is that the positioning of switches and sensors does not</p><p>take account of the contribution of natural light. This is a particular</p><p>fault in offices with atria. In some of the worst cases activating lights in</p><p>an office area can switch on all lights along the exit route and in</p><p>extreme instances, throughout the whole circulation area. A balance</p><p>should be struck between optimum safety and the profligate use of</p><p>energy.</p><p>AIAC-Ch15.qxd 03/25/2005 17:28 Page 190</p><p>Switches</p><p>A common failing is that switches are not positioned logically in terms</p><p>of their relation to the fittings and behaviour patterns of occupants.</p><p>Switches remote from fittings lead to uncertainty as to the status of the</p><p>lights. The answer would be to include a red ‘live’ light in the switch.</p><p>Remote infra-red switching is an efficient and effortless system,</p><p>provided the operation zone focuses down to the size of an individual</p><p>workstation. Where switching is not ergonomically appropriate the</p><p>tendency once again is for lights to be left on permanently.</p><p>System management</p><p>One major reason why certain high profile energy efficient buildings fail</p><p>to meet expectations is because of deficiencies at the level of system</p><p>management. It may be that system interfaces are not well understood</p><p>by staff. Even service managers and suppliers are occasionally not as</p><p>well informed as they should be. The problem is exacerbated if the</p><p>original software source is no longer available.</p><p>System complexity is another problem. If services managers are</p><p>not conversant with the intricacies of a system, they will tend to operate</p><p>it at or near its optimum on the principle that overkill masks lower order</p><p>problems and safeguards one’s back. Also, overcomplex systems dis-</p><p>courage interference and adjustment in case the outcome is worse and</p><p>defies a remedy. Calling out specialists to make adjustments can be</p><p>expensive thus tempting managers to prefer to operate the system</p><p>below its design efficiency.</p><p>Complex systems can also be inflexible. In some cases the system’s</p><p>programme no longer serves the functions of the building. In extreme</p><p>cases this has led to the complete abandonment of the system.</p><p>In some cases the fault for poor system performance lies with office</p><p>managers who fail to inform the staff of the operational characteristics,</p><p>cost and energy implications of the system. For example, in one</p><p>instance, staff were not told of the fact that pressing a switch twice</p><p>would turn on extra lights. The human factor is of prime importance.</p><p>Good communication between management and staff can achieve a</p><p>satisfactory performance from a less than perfect system. Inadequate</p><p>communication can undermine the virtues of the best possible system</p><p>design.</p><p>There is also the situation that office managers sometimes fail to</p><p>address the more subtle needs of staff, gearing the system to crude</p><p>averages with the result that nobody is satisfied.</p><p>The increasing popularity of flexible working hours is causing diffi-</p><p>culties. Light controls may have been designed for fixed working hours</p><p>and set lunch times. This is another instance where the complications</p><p>and cost of modifying the system to respond to new work practices may</p><p>LIGHTING – AND HUMAN FAILINGS</p><p>191</p><p>AIAC-Ch15.qxd 03/25/2005 17:28 Page 191</p><p>be unacceptable and therefore the system is abandoned. There has</p><p>been a case where all lights in an office were operated from a central</p><p>control desk. The desk only operated from 09.00 to 17.30 hours. Since</p><p>staff became able to work flexible hours, it meant that those working</p><p>after 17.30 were obliged to leave the lights burning all night.</p><p>Another potential source of conflict between design and operation</p><p>is when a single occupancy office reverts to multiple occupancy. It is</p><p>usual for the principal tenant to have overall control of the services.</p><p>Variable working patterns and conflicting needs often means that lights</p><p>are left on unnecessarily.</p><p>A relatively recent trend in the production of buildings is for the</p><p>design to be separated from the fitting-out. The architect and services</p><p>designer may produce an elegant energy-efficient concept which can</p><p>be totally vitiated by the fitting-out contractor who has not been</p><p>informed of the energy saving features and consequent operational</p><p>constraints of the design. Even worse is the situation where the sub-</p><p>contractor deliberately ignores the design objectives of the architect</p><p>and engineer in order to keep down costs. The problem of discontinu-</p><p>ity between design intention and fitting-out can be particularly acute in</p><p>the case of refurbishments.</p><p>Air conditioned offices</p><p>These present a different set of problems for designers. The psycho-</p><p>logical effect of a space hermetically sealed from the outside world is to</p><p>suggest an environment designed to overcome nature and be wholly</p><p>distinct from it. As a result, the inhabitants tend to regard it as natural</p><p>that all the services should be fully used all the time. If, in addition, the</p><p>facades feature solar tinted glass, even more lighting is used to com-</p><p>pensate for the constantly gloomy outlook.</p><p>Lighting – conditions for success</p><p>Open plan installations which offer occupant satisfaction and energy</p><p>efficiency usually satisfy four conditions:</p><p>● The design is straightforward and comprehensible, avoiding over-</p><p>complexity.</p><p>last 50 years. According to Sir David King, UK</p><p>Chief Government Scientist, this is the highest concentration in 55</p><p>million years. Then there was no ice on the planet. The previous</p><p>highest concentration was 300 ppmv 300 000 years ago (New</p><p>Scientist, 29 January 2000, pp. 42–43). At the present rate of emis-</p><p>sion, concentrations could reach 800–1000 ppmv by 2100. Even if</p><p>emissions were to be reduced by 60 per cent against 1990 levels by</p><p>2050 this will still raise levels to over 500 ppmv with unpredictable</p><p>consequences due to the fact that CO2 concentrations survive in the</p><p>atmosphere for at least 100 years.</p><p>● Altogether it would seem that a temperature rise of at least 6�C is</p><p>very possible with the worst case scenario now rising to 11.5�C.</p><p>Bearing in mind the observed rate of temperature increase as</p><p>mentioned above, the aim now should be to prevent the planet</p><p>crossing the threshold into runaway global warming whereby mutu-</p><p>ally reinforcing feedback loops become unstoppable.</p><p>● Spring in the northern hemisphere is arriving at least one week</p><p>earlier than 20 years ago; some estimates put it at 11 days. A</p><p>40-year survey by Nigel Hepper at the Royal Botanical Gardens at</p><p>Kew involving 5000 species indicates that spring is arriving ‘several</p><p>weeks earlier’. A study of European gardens found that the growing</p><p>season has expanded by at least ten days since 1960. Munich</p><p>scientists studied 70 botanical gardens from Finland to the Balkans</p><p>(616 spring records and 178 autumn). The conclusion was that</p><p>spring arrived on average six days earlier and autumn five days later</p><p>over a 30-year period (Nature, February 1999).</p><p>● Extreme heat episodes are becoming a feature of hitherto temperate</p><p>climate zones. The majority of heat-related deaths are due to a</p><p>lethal assault on the blood’s chemistry. Water is lost through sweat-</p><p>ing and this leads to higher levels of red blood cells, clotting factors</p><p>and cholesterol. The process starts within 30 minutes of exposure to</p><p>sun. The summer of 2003 saw heatwaves across Europe that were</p><p>exceptional, not only in terms of peak temperatures but also their</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>10</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 10</p><p>duration. According to the Earth Policy Institute in Washington DC,</p><p>35 000 died in August across Europe and 14 800 in France alone</p><p>from heat-related causes. Other estimates put the figures at 20 000</p><p>and 11 000 respectively. According to scientists in Zurich reporting</p><p>in ‘Nature on-line’, this kind of sustained summer temperature</p><p>could normally be expected every 450 years. Towards the latter part</p><p>of the century they predict such an event every second year. On</p><p>4 February 2004 the temperature in central England reached 12.5�C</p><p>which was the highest early February temperature since records</p><p>began in 1772 according to the UK Meteorological Office. That</p><p>month was also the occasion of a severe heatwave in Brisbane,</p><p>North Australia, where there were 29 sudden deaths in one night.</p><p>● One of the predicted results of global warming is that there will be</p><p>greater extremes of weather, which not only means higher temper-</p><p>atures but also more extensive swings of atmospheric pressure.</p><p>Research at the University of Lille has indicated that when the pres-</p><p>sure falls below 1006 millibars or rises above 1026 millibars the risk</p><p>of heart attacks increases by 13 per cent. The study also showed</p><p>that a drop in temperature of 10�C increases the risk of a heart</p><p>attack by the same percentage (reported at a meeting of the</p><p>American Heart Association, Dallas, November 1998). According to</p><p>the UN Environment Protection Agency director, the cost of prema-</p><p>ture death due to rising numbers of heatwaves is reckoned to be</p><p>£14 billion a year in the EU and £11 billion in the US. Worldwide the</p><p>assessment is £50 billion.</p><p>● Oceans are the largest carbon sink. As they warm they are becom-</p><p>ing less efficient at absorbing CO2. The latest prediction is that the</p><p>carbon absorption capacity of oceans will decline by 50 per cent as</p><p>sea temperatures rise.</p><p>● Methane emissions from natural wetlands and rice paddy fields are</p><p>increasing as temperatures rise. To repeat, methane is a much</p><p>more potent greenhouse gas than CO2 and levels are rising rapidly.</p><p>● The year 2000 saw an unprecedented catalogue of warnings. The</p><p>warming that is eroding Europe’s largest glacier in Iceland also cre-</p><p>ated clear water across the North West Passage at the top of</p><p>Canada making navigation possible. This has not happened since</p><p>prehistoric interglacial warming.</p><p>Finally, the assumption generally held by policy makers is that a steady</p><p>rise in CO2 concentrations will produce an equally steady rise in tempera-</p><p>ture. The evidence from ice cores reveals that the planet has sometimes</p><p>swung dramatically between extremes of climate in a relatively short time</p><p>due to powerful feedback that tips the system into a dramatically different</p><p>steady state. Scientists meeting for a workshop in Berlin in 2003 con-</p><p>cluded, on the evidence of climate changes to date, that the planet could</p><p>be on the verge of ‘abrupt, nasty and irreversible’ change (Bill Clark,</p><p>Harvard University, quoted in New Scientist, 22 November 2003).</p><p>CLIMATE CHANGE – NATURE OR HUMAN NATURE?</p><p>11</p><p>AIAC-Ch01.qxd 03/25/2005 17:08 Page 11</p><p>12</p><p>Chapter</p><p>Two</p><p>Predictions</p><p>There is considerable scientific research effort being targeted on the</p><p>likely consequences of climate change particularly within the scenario</p><p>that the industrialised nations will continue indefinitely with ‘busi-</p><p>ness as usual’ (BaU). This BaU scenario assumes some changes and</p><p>improvements in efficiency in technology. Here are some of the</p><p>predictions.</p><p>● Historic sea levels are well recorded in the Bahamas and Bermuda</p><p>because these islands have not been subject to tectonic rise and</p><p>fall. Ancient shorelines show that, at its extreme, sea level was 20 m</p><p>(70 ft) above the present level during an interglacial period 400 000</p><p>years ago. This would occur if all the world’s vast ice sheets disinte-</p><p>grated. There is a serious risk of this happening to the West</p><p>Antarctic and Greenland ice sheets and their loss would mean a</p><p>12 m rise in sea level (Geology, vol. 27, p. 375).</p><p>● In 2001 Antarctic scientists indicated that sea levels could rise by</p><p>6 m (20 ft) within 25 years (Reuters). Ultimately, ‘when Antarctica</p><p>melts it [sea level] will be another 110 metres’ (Sir David King, The</p><p>Guardian, 14 July 2004).</p><p>● Many millions of people live below one metre above sea level. For</p><p>example, Singapore and its reclaimed territories will be at risk if the</p><p>sea level rises above 20 cm. The Thames barrage is already</p><p>deemed to be inadequate. Hamburg is 120 kilometres from the sea</p><p>but could be inundated. The mean high tidal water level has</p><p>increased between 40 and 50 cm since the 1970s.</p><p>● The condition of the Greenland ice cap is another cause for con-</p><p>cern. According to one scenario ‘warming of less than 3�C – likely in</p><p>that part of the Arctic within a couple of decades – could start a run-</p><p>away melting that will eventually raise sea levels worldwide by</p><p>seven metres’ (New Scientist, ‘Doomsday Scenario’, words attrib-</p><p>uted to Jonathan Gregory of the Hadley Centre, 22 November</p><p>2003). According to a BBC report (28 July 2004) the Greenland ice</p><p>sheet is melting ten times faster than previously thought. Since May</p><p>2004 the ice thickness has reduced by 2–3 m. The same report</p><p>stated that Alaska is 8�C warmer than 30 years ago.</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 12</p><p>PREDICTIONS</p><p>13</p><p>Figure 2.1</p><p>Land below 5 metre and 10 metre</p><p>contours</p><p>● In the UK rising sea levels threaten 10 000 hectares of mudflats and</p><p>salt marshes. But the most serious threat is to 50 per cent of</p><p>England’s grade 1 agricultural land which lies below the 5 m con-</p><p>tour (Figure 2.1). Salination following storm surges will render this</p><p>land sterile. The University of East Anglia Environmental Risk Unit</p><p>predicts that the 1 in 100 year storm and related floods will show a</p><p>return rate by 2030 for:</p><p>Milford Haven 3.5 yrs</p><p>Cardiff 5 yrs</p><p>Portland 5 yrs</p><p>Newhaven 3 yrs</p><p>Colchester 4 yrs</p><p>● A report from a committee chaired by the UK’s Chief Government</p><p>Scientist, Sir David King, predicts that global warming, coastal ero-</p><p>sion and the practice of building on flood plains will increasingly</p><p>raise the level of risk of loss of life and extensive property damage.</p><p>The panel of scientists behind the report considered four scenarios.</p><p>The two worst case scenarios more or less correspond to the IPCC</p><p>Land below 5 m AOD</p><p>Land between 5 and 10 m AOD</p><p>Lowestoft</p><p>Colchester</p><p>Sheerness</p><p>Newhaven</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 13</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>14</p><p>Business as Usual scenario in which there is unrestricted economic</p><p>development and hardly any constraints on pollution. The report</p><p>concludes that the population at risk from coastal erosion and</p><p>flooding could increase from 1.6 million today to 3.6 million by the</p><p>2080s. The cost to the economy could be £27 billion per year</p><p>(Future Flooding, a report from the Flood and Coastal Defence</p><p>Project of the Foresight Programme, April 2004) (Figure 2.2).</p><p>In an interview with The Guardian (14 July 2004) Sir David King</p><p>stated: You might think it is not wise, since we are melting ice so fast,</p><p>to have built our big cities on the edge of the sea where it is now</p><p>obvious they cannot remain. On current trends, cities like London,</p><p>New York and New Orleans will be among the first to go. He went</p><p>on: ‘I am sure that climate change is the biggest problem that civili-</p><p>sation has had to face in 5000 years’ which gives added weight to his</p><p>pronouncement in January 2004 that climate change poses a</p><p>greater threat than international terrorism.</p><p>● It was stated earlier that the geological record over 300 million</p><p>years shows considerable climate swings every 1–2000 years until</p><p>8000 years ago, since which time the swings have been much more</p><p>moderate. The danger is that increasing atmospheric carbon up to</p><p>treble the pre-industrial level will trigger a return to this pattern.</p><p>The IPCC Scientific Committee believes that the absolute limit of</p><p>Figure 2.2</p><p>Areas in England and Wales at risk of</p><p>flooding by 2080 under worst case</p><p>scenario (from the Office of Science</p><p>and Technology Foresight Report,</p><p>Future Flooding, April 2004)</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 14</p><p>PREDICTIONS</p><p>15</p><p>accumulation of atmospheric carbon should be fixed at double the</p><p>pre-industrial level at around 500 parts per million by volume</p><p>(ppmv). Even this will have dramatic climate consequences.</p><p>● The paleoclimate record shows that generally cooling occurred at a</p><p>slow rate, but that warming was rapid as stated earlier, for example</p><p>12�C in a lifetime.</p><p>● Global warming poses a serious threat to health. Pests and</p><p>pathogens are migrating to temperate latitudes. It is already widely</p><p>understood that illnesses like vector borne malaria and</p><p>Leishmaniasis (affecting the liver and spleen) are predicted to</p><p>spread to northern Europe. The UK Department of Health predicts</p><p>that, by 2020, seasonal malaria will have a firm foothold in southern</p><p>Britain, including the deadly plasmodium falciparum strain which</p><p>kills around one million children a year in Africa (Figure 2.3). The</p><p>incidence of the fatal disease West Nile fever has increased in warm</p><p>temperate zones. New York had an outbreak in 1999. The</p><p>Department also estimated that there will be around 3000 deaths a</p><p>year from heatstroke – a prediction seriously understated if the</p><p>summer of 2003 sets the pace of change. Higher temperatures</p><p>would also increase the incidence of food poisoning by 10 000</p><p>(Department of Health review of the effects of climate change on</p><p>the nation’s health, 9 February 2001).</p><p>● A warmer atmosphere means greater evaporation with a conse-</p><p>quent increase in cloud cover. IPCC scientists consider that the net</p><p>Figure 2.3</p><p>Predicted spread of seasonal malaria in</p><p>Britain by 2020</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 15</p><p>effect will be to increase global warming. Water vapour is a potent</p><p>greenhouse gas.</p><p>● Historically relatively abrupt changes in climate have been triggered</p><p>by vegetation. For example, average temperature rose by 5�C in</p><p>10 years 14 000 years ago. Earlier it was said that the paleoclimate</p><p>record shows that in the past the explosive growth of vegetation</p><p>absorbed massive amounts of atmospheric carbon resulting in a</p><p>severe weakening of the greenhouse effect and a consequent ice age.</p><p>Nature could still be the deciding factor. The Hadley Centre forecasts</p><p>that global warming will cause forests to grow faster over the next 50</p><p>years, absorbing more than 100 billion tonnes of carbon. However,</p><p>from about 2050 the increasing warming will kill many of the forests,</p><p>thus returning 77 gigatonnes (billion) of carbon to the atmosphere.</p><p>This will bring a high risk of runaway global warming. Already there is</p><p>evidence of changes in growth patterns in the Amazon rainforest.</p><p>Taller, faster growing trees are taking over from the slower growing</p><p>trees of the understorey of the forest. This is attributed to the higher</p><p>levels of CO2 in the atmosphere. In the short term this could mean a</p><p>net loss in the carbon fixing capacity of the forest since the under-</p><p>storey trees are slower growing and denser in carbon content. Canopy</p><p>trees are faster growing and lower in carbon content. In the longer</p><p>term the latter trees are likely to be more susceptible to die-back</p><p>through heat and drought (New Scientist, p. 12, 13 March 2004).</p><p>● A report from the Calicut University, Kerala, by British, Indian and</p><p>Nepalese researchers predicts that the great rivers of northern India</p><p>and Pakistan will flow strongly for about 40 years causing wide-</p><p>spread flooding. After this date most of the glaciers will have disap-</p><p>peared creating dire problems for populations reliant on rivers fed</p><p>by melt ice like the Indus and Ganges. It is estimated that all the</p><p>glaciers in the central and eastern Himalayas will disappear by</p><p>2035. Melting glaciers in the Andes and Rocky Mountains will cause</p><p>similar problems in the Americas (New Scientist, p. 7, 8 May 2004).</p><p>● Another danger is posed by the rapid accumulation of meltwater</p><p>lakes. Meltwater is held back by the mound of debris marking the</p><p>earlier extremity of the glacier path. These mounds are unstable</p><p>and periodically collapse with devastating results. It is predicted</p><p>that the largest of these lakes in the Sagarmatha National Park in</p><p>Nepal currently holding 30 million cubic metres of water will break</p><p>out within five years (New Scientist, p. 18, 5 June 1999). The world-</p><p>wide melting of glaciers and ice caps will contribute 33 per cent of</p><p>the predicted sea level rise (IPCC).</p><p>● The head of research at Munich Re, the world’s largest reinsurance</p><p>group, predicts that claims within the decade 2040–2050 will have</p><p>totalled £2000 billion based on the IPCC estimates of the rise in</p><p>atmospheric carbon. He states: ‘There is reason to fear that climatic</p><p>changes in nearly all regions of the Earth will lead to natural</p><p>catastrophes of hitherto unknown force and frequency. Some regions</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>16</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 16</p><p>will soon become uninsurable’ (quoted in The Guardian, 3 February</p><p>2001).</p><p>● We have to add to these natural events the prediction that there will</p><p>be a substantial increase in world population, mostly in areas which</p><p>can least accommodate it. At present the greatest concentrations of</p><p>population are in coastal regions which will be devastated if sea</p><p>level rise predictions are fulfilled. The UN Population Division</p><p>estimates that the world figure will reach 8.9 billion by 2050. The US</p><p>Census Bureau predicted in March 2004 that the present popula-</p><p>tion of 6.2 billion will rise to 9.2 billion by that date. It then believes</p><p>that the rate of fertility will fall below the replacement level. Even at</p><p>present 1.3 billion, or one third, of the total world population live in</p><p>extreme poverty on less than $1 per day.</p><p>Recent uncertainties</p><p>An article of 10 July 2004 in New Scientist was headed ‘Peat bogs</p><p>harbour carbon time bomb’. Research in the University of Wales at</p><p>Bangor indicates that ‘The world’s</p><p>peatland stores of carbon are emp-</p><p>tying at an alarming rate’ (Chris Freeman). Peat bogs store huge</p><p>quantities of carbon and the evidence is that this is leaching into rivers</p><p>in the form of dissolved organic carbon (DOC) at the rate of about 6 per</p><p>cent per year. Bacteria in rivers rapidly convert DOC into CO2 that is</p><p>released into the atmosphere. Recent research shows that DOC in</p><p>Welsh rivers has increased 90 per cent since 1988. Freeman predicts</p><p>that, by the middle of the century, DOC from peat bogs could be as</p><p>great a source of atmospheric CO2 as the burning of fossil fuels. It</p><p>appears to be another feedback loop in that an increase in CO2 in the</p><p>atmosphere is absorbed by vegetation which in turn releases it into the</p><p>soil moisture. There it feeds bacteria in the water which, in turn, breaks</p><p>down the peaty soil allowing it to release stored carbon into rivers.</p><p>Global warming is causing peat bogs to dissolve.</p><p>The uncertainty with perhaps the greatest potential to derail</p><p>current predictions about global warming is the role of the clouds,</p><p>described by New Scientist as ‘the wild card in global warming predic-</p><p>tions. Add them to climate models and some frightening possibilities</p><p>fall out’ (Fred Pierce, New Scientist, 24 July 2004). The worry is that</p><p>global warming will either reduce the global level of cloud cover or</p><p>change the character of the clouds and their influence on solar radiation.</p><p>Recent modelling conducted by James Murphy of the Met Office</p><p>Hadley Centre for Climate Prediction has factored in a range of uncer-</p><p>tainties in cloud formations such as cloud cover, the lifetime of clouds</p><p>and their thickness. The model suggested that warming could reach up</p><p>to 10�C on the basis of a doubling of atmospheric CO2 which is widely</p><p>regarded as inevitable. David Stainforth of Oxford University warns of</p><p>the possibility of a 12�C rise by the end of the century. Cirrus clouds</p><p>PREDICTIONS</p><p>17</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 17</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>18</p><p>are the most efficient at reflecting heat back to Earth and these are</p><p>becoming more prevalent. It is expected that the next range of predic-</p><p>tions by the IPCC due in 2007 will take account of feedback from cloud</p><p>cover and produce significantly higher worst case temperature scenar-</p><p>ios (from New Scientist, 24 July 2004, pp. 45–47).</p><p>Another cause for concern stems from research finding from the</p><p>Universities of Sheffield and Bristol. In the Eocene epoch 50 million years</p><p>ago there was a catastrophic rise in temperature with seas 12�C warmer</p><p>than today. The evidence comes from oxygen trapped in the shells of</p><p>marine fossils. This leaves a distinct isotope pattern which gives an indi-</p><p>cation of the sea temperature at a given time. Evidence from plant fos-</p><p>sils has shown that CO2 levels were similar to the present day and</p><p>therefore could not have been responsible for that level of warming. It</p><p>transpires that this was due to emissions of methane, ozone and nitrous</p><p>oxide, all more powerful greenhouse gases than CO2. At the time the</p><p>Earth was carpeted with wetlands which produced high levels of</p><p>methane which led to runaway warming. At the present time it is cattle,</p><p>rice fields and termites which are major sources of the gas. According to</p><p>Professor Beerling of Sheffield University: ‘Methane is being produced</p><p>in increasing amounts thanks to the spread of agriculture in the tropics.</p><p>Rice is a particularly intensive source. Car exhaust gases and nitrogen</p><p>fertilisers are also increasing other gases’ (The Observer, 11 July 2004).</p><p>With a predicted steep rise in emissions from transport over the next</p><p>decades, the latter point is a serious cause of concern.</p><p>It is sobering to compare how, according to the UN, different coun-</p><p>tries are making progress or otherwise in cutting their CO2 emissions.</p><p>It should be noted that the improvement in the case of Russia is due to</p><p>the collapse of its heavy industry since 1990 (Figure 2.4).</p><p>Up to now the focus has been on limiting CO2 emissions almost to</p><p>the exclusion of other greenhouse gases. It is time to spread the net</p><p>more widely if there is not to be a rerun of the Eocene catastrophe.</p><p>Figure 2.4</p><p>CO2 emissions by principal nations</p><p>(UNFCCC 2004)</p><p>USA</p><p>European Union</p><p>Japan</p><p>China</p><p>India</p><p>EU</p><p>China</p><p>Russia</p><p>Japan</p><p>India</p><p>1000 2000</p><p>+ +</p><p>+ + +</p><p>3000 4000 5000</p><p>SOURCES: UNFCCC (China figures from IEA)</p><p>6000</p><p>CO2 EMISSIONS (1,000 MILLION TONNES)</p><p>1990</p><p>2002</p><p>1994 only</p><p>0</p><p>++1999+++2001 (both China figures include Hong Kong)</p><p>United States</p><p>Russia</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 18</p><p>PREDICTIONS</p><p>19</p><p>What is being done?</p><p>The core of the problem lies in the disparity between the industrial and</p><p>developing countries in terms of carbon dioxide emission per head.</p><p>Despite all the international conventions carbon dioxide emissions</p><p>from developed countries are showing little sign of abating. The USA at</p><p>twice the European average is still increasing its emissions which cur-</p><p>rently stand at 23 per cent of the world’s total. The average citizen in the</p><p>North American continent is responsible for around 6 tonnes of carbon</p><p>per year. In Europe it is about 2.8 tonnes per person. Though starting</p><p>from a very low base, the most rapidly rising per capita emissions are</p><p>occurring in Southeast Asia, India and China.</p><p>As a first step on the path of serious CO2 abatement an accord was</p><p>signed by over 180 countries in 1997 in Kyoto to cut CO2 emissions by</p><p>5.2 per cent globally based on 1990 levels. It has to be remembered</p><p>that the UN IPCC scientists stated that a 60 per cent cut worldwide</p><p>would be necessary to halt global warming, later endorsed by the UK</p><p>Royal Commission on Pollution. The US has refused to ratify Kyoto but</p><p>Russia has signed up which meant that the Treaty came into force in</p><p>February 2005. The UK was on track to meet its 12.5 per cent reduction</p><p>target thanks to the gas power programme and the collapse of heavy</p><p>industry. However, these benefits have now been offset by the growth</p><p>in emissions from transport. In 2003 there was a 1–2 per cent increase in</p><p>CO2 emissions. Globally the year 2003 witnessed a significant rise in the</p><p>level of atmospheric carbon to 3 ppm per year – nearly double the aver-</p><p>age for the past decade. If aircraft emissions were also taken into</p><p>account the situation would be substantially worse.</p><p>One great anomaly is that air travel is excluded from the calcula-</p><p>tions of CO2. The Parliamentary Environmental Audit Committee (EAC)</p><p>forecasts that by 2050 air transport will be responsible for two thirds of</p><p>all UK greenhouse gas emissions. The Department of Transport expects</p><p>the numbers flying in and out of the UK to rise from 180 million in 2004</p><p>to 500 million in 2030 (reported in The Observer, 22 March 2004).</p><p>Aviation’s share of the UK’s CO2 emissions will have increased four-fold</p><p>by 2030. At the same time it should be noted that CO2 accounts for only</p><p>one third of the global warming caused by aircraft (Tom Blundell and</p><p>Brian Hoskins, members of the Royal Commission on Environmental</p><p>Pollution, New Scientist, 7 August 2004, p. 24).</p><p>Even more of a problem faces the USA. Kyoto set its reduction</p><p>target against the 1990 level at 7 per cent. However, since then it has</p><p>enjoyed a significant economic boom with a consequent increase in</p><p>CO2 emissions. To meet the Kyoto requirement it would now have to</p><p>make a cut of 30 per cent. The only way it would be prepared to</p><p>consider this kind if target is by carbon trading, not, in itself, an illegiti-</p><p>mate recourse. However, it all depends on the currency of exchange.</p><p>The US wants to use trees to balance its carbon books. Planting forests</p><p>may look attractive but it presents three problems.</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 19</p><p>First, there have been attempts to equate the sequestration capac-</p><p>ity of trees with human activities such as driving cars, so, five trees</p><p>could soak up the carbon from an average car for one year, or 40 trees</p><p>counteract the carbon emitted by the average home in five years.</p><p>Unfortunately there is not a reliable method of accounting for the</p><p>sequestration</p><p>capacity of a single tree let alone a forest. Another prob-</p><p>lem recently exposed in the USA is that forests are inclined to burn</p><p>down. The last point refers back to the Hadley Centre prediction that</p><p>there will be accelerating forest growth over the next 50 years, then</p><p>rapid die-back, releasing massive quantities of carbon into the atmos-</p><p>phere. Overall, forests could possibly end up huge net contributors to</p><p>global warming.</p><p>This seems to have been uppermost in the minds of the European</p><p>delegates to the conference in The Hague in November 2000 when</p><p>they refused to sign an agreement which allowed the USA to continue</p><p>with business as usual in return for planting trees.</p><p>In the final analysis, if governments and society fail to respond to</p><p>the imperatives set by climate change, what they cannot escape is</p><p>the inevitability of dramatic increases in the cost of fossil-based</p><p>energy as demand increasingly outstrips supply as reserves get ever</p><p>closer to exhaustion. Market forces are already powering the drive</p><p>towards renewable energy in some industrialised countries. When</p><p>you see oil companies investing in renewables then it must be the</p><p>dawning of the realisation that saving the planet might just be cost</p><p>effective.</p><p>The outlook for energy</p><p>A report published in May 2004 from the European Union called</p><p>‘World Energy, Technology and Climate Change Outlook’ offers an</p><p>insight into a future still dominated by fossil-based energy. It predicts</p><p>that CO2 emissions will increase by 2.1 per cent per year for the next</p><p>30 years whilst energy use will rise by 1.8 per cent. The reason for the</p><p>difference is that there will be increasing use of coal as oil and gas</p><p>prices rise and reserves contract. It also estimates a fall in the share of</p><p>energy from renewables from 13 per cent today to 8 per cent. This is</p><p>mainly because growth in renewables will not keep pace with overall</p><p>energy consumption.</p><p>The report expects that energy use in the US will increase by 50 per</p><p>cent and in the EU by 18 per cent over the same period. Developing</p><p>countries, especially China and India, will increase their share of global</p><p>CO2 emissions from 30 per cent in 1990 to 58 per cent in 2030. China is</p><p>the world’s second biggest emitter of greenhouse gases and the</p><p>world’s biggest producer of coal. To meet its expected energy needs</p><p>China plans to nearly treble its output from coal fired power stations by</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>20</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 20</p><p>PREDICTIONS</p><p>21</p><p>2020. These new power plants are not being constructed to accommo-</p><p>date future CO2 sequestration equipment and they are likely to be in</p><p>service for 50 years. Oil consumption has doubled in the last 20 years</p><p>and now stands at 80 million barrels per day, an all time high. So, for</p><p>decades to come, with cities like Shanghai growing at an exponential</p><p>rate, China is virtually ruling out measures to mitigate its CO2 emissions,</p><p>which, as a developing country, it is not required to do.</p><p>As the economies of the world power ahead on the back of fossil</p><p>fuels, the spectre of diminishing reserves heightens anxieties within the</p><p>corridors of government. The oil companies estimate that reserves will</p><p>be exhausted within about 40 years but that is not so much the prime</p><p>issue. According to Stephen Lewis, City economic analyst, ‘the kind of</p><p>growth rates to which oil consuming countries are committed appear to</p><p>be generating the demand for oil well above the underlying growth in</p><p>the rate of supply . . . the US, the Middle East, the North Sea . . . all</p><p>appear to be past their production peaks’ (The Guardian, 9 August 2004).</p><p>There are conflicting estimates, but petroconsultants who advise</p><p>the government claim that only one new barrel of oil is discovered for</p><p>every four that are used. Their estimate is that we are only two years</p><p>away from the peak of oil production.</p><p>By 2020 the UK will be importing 80 per cent of its energy based on</p><p>the current rate of consumption. The histogram in Figure 2.5 indicates</p><p>the rate of decline of UK reserves of both oil and gas. As regards gas, the</p><p>major reserves are located within countries that do not have a good</p><p>record of stability. The North Sea reserves are already diminishing with a</p><p>Figure 2.5</p><p>UK oil and gas reserves to 2020</p><p>(Association for the Study of Peak Oil</p><p>and Gas 2004)1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 2015 2018</p><p>0.0</p><p>0.5</p><p>1.0</p><p>1.5</p><p>2.0</p><p>2.5</p><p>3.0</p><p>3.5</p><p>4.5</p><p>4.5</p><p>5.0</p><p>O</p><p>il</p><p>eq</p><p>ui</p><p>va</p><p>le</p><p>nt</p><p>(</p><p>m</p><p>m</p><p>bo</p><p>e/</p><p>da</p><p>y)</p><p>Gas-Possible</p><p>Oil-Possible</p><p>Gas-2P</p><p>Oil-2P</p><p>Gas</p><p>Oil</p><p>Already produced Future production</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 21</p><p>life expectancy of 15–20 years. The government has acknowledged that,</p><p>by 2020, 90 per cent of the UK’s gas will come from Russia, Iran and</p><p>Nigeria (Ministry of Defence, 8 February 2001).</p><p>For the US the Department of Energy estimates that imports of</p><p>oil will rise from 54 per cent in 2004 to 70 per cent by 2025 due to its</p><p>declining reserves and increasing consumption. Add to this the fact</p><p>that at least half the remaining global reserves will be located in</p><p>five autocracies in the Middle East who have already demonstrated</p><p>their ability to manipulate prices causing the oil shocks of the 1970s.</p><p>These states account for 35 per cent of the market, the point at which it</p><p>is considered they are able to control prices at a time of rising demand,</p><p>especially by developing countries on the rapid road to developed</p><p>status.</p><p>According to the environmental policy analyst Dr David Fleming it</p><p>is ‘not possible that we can survive without a dramatic increase in the</p><p>price of oil’ (The Guardian, 2 March 2000). The government was warned</p><p>that another oil price shock could trigger a stock market crash, or even</p><p>war. In the oil shocks of the 1970s we were extricated from long-term</p><p>pain by the discovery of large oil reserves in the North Sea and Alaska.</p><p>This time there are no escape routes. The Kuwait episode then the Iraq</p><p>war should remind us of the sensitivity of the situation.</p><p>The world is one huge combustion engine which consumes 74 mil-</p><p>lion barrels of oil a day to keep it running for now! At the present time</p><p>in China one person in 125 has a car. The Chinese economy is growing</p><p>at 8–10 per cent a year. It has joined the World Trade Organisation and</p><p>opened its markets to international trade which gives additional impe-</p><p>tus to economic growth. In no time there will be one person in 50 then</p><p>perhaps one in 20 owning a car. Even without including the prospects</p><p>for China the current demand for oil worldwide is growing at 2 per cent</p><p>a year. By 2020 it is estimated that there will be one billion cars on the</p><p>world’s roads. At the same time petrol geologists estimate that produc-</p><p>tion of oil will peak in the first decade of 2000 and then output will</p><p>decline by 3 per cent a year. Oil geologist Colin J. Campbell says we are</p><p>‘at the beginning of the end of the age of oil’. He predicts that after</p><p>2005 there will be serious shortages of supply with steeply rising prices</p><p>and by 2010 a major oil shock reminiscent of the 1970s except that then</p><p>there were huge reserves to be tapped. There are still large reserves</p><p>but they are located in places like the states around the Caspian basin</p><p>which Russia regards as its sphere of influence – not much comfort to</p><p>the west, in particular the UK, where it is expected that its North Sea</p><p>fields will be exhausted by 2016.</p><p>An updated 2004 scenario for world peak oil production by Colin</p><p>Campbell shows, in a graph published on the website of the Association</p><p>for the Study of Peak Oil (ASPO), that both gas and oil worldwide will</p><p>peak around 2008 (Figure 2.6).</p><p>Beyond 2008, increasing price volatility for both oil and gas seems</p><p>inevitable.</p><p>ARCHITECTURE IN A CLIMATE OF CHANGE</p><p>22</p><p>AIAC-Ch02.qxd 03/25/2005 17:09 Page 22</p><p>PREDICTIONS</p><p>23</p><p>The nuclear option</p><p>The UK has problems regarding its nuclear capacity. Recently questions</p><p>have been raised about the government’s estimates of future genera-</p><p>tion capacity within the nuclear industry. Environment Data Services</p>Furthermore, in many casesthere are not enough sensors and lighting zones to take account oflocalised variations in daylight due to orientation or shading. As a rule ofthumb, to avoid the need to make small-scale adjustments, lights shouldnot go off until the illuminance level is about twice the design level.AIAC-Ch15.qxd 03/25/2005 17:28 Page 189ARCHITECTURE IN A CLIMATE OF CHANGE190GlareAnother rule of thumb which is observed by designers is that ‘if youcan’t see the sky the daylight level is inadequate’. The result is tall win-dows to give maximum daylight penetration. This carries the attendantrisk of glare unless workstations are properly positioned in relation tothe window. In most cases this will mean desks at right angles to theexternal wall and the VDU viewing axis parallel to the window plane.One option is to resort to automatic blinds. Occupiers sometimescomplain that the spontaneous action of the blind is an irritant andrepresents a denial of individual choice. Local manual override is thepreferred answer.Recent developments in glass technology referred to earlier interms of electrochromic glass offer solutions to these problems, espe-cially if it can be controlled on an individual pane basis.Another problem that occurs is that lighting and blinds controls arenot co-ordinated. Lights tend to stay on regardless of the position ofthe blinds. The operation of externally positioned blinds can be frus-trated by adverse weather conditions, especially high winds.Dimming control and occupancy sensingClosed loop systems are designed to provide a constant level of desk-top illuminance. However, as the level of outside light fluctuates, soindividuals may wish to vary desktop light levels to minimise contrast.On a bright day a constantly lit desk would appear gloomy.There are obvious advantages to light switching which is respon-sive to a human presence, but even this technology is not devoid ofproblems. The adjustment of the sensors is a matter of fine tuning. Forexample, they may not be sufficiently sensitive to the movements ofpeople engaged in high concentration tasks. Alternatively they may beso sensitive that passers-by trigger the switch causing a distraction. Inpractice it is often difficult to locate sensors to suit occupancy patternsand work requirements especially in open plan offices where worksta-tions may frequently be relocated. The ideal solution is to rely on manualswitching for the ‘on’ and automatic switching for the ‘off’.Occupancy sensors achieve their optimum value in service areasand circulation spaces. These are areas which are frequently over-looked yet they can use more energy pro rata than office spaces. Onecommon fault is that the positioning of switches and sensors does nottake account of the contribution of natural light. This is a particularfault in offices with atria. In some of the worst cases activating lights inan office area can switch on all lights along the exit route and inextreme instances, throughout the whole circulation area. A balanceshould be struck between optimum safety and the profligate use ofenergy.AIAC-Ch15.qxd 03/25/2005 17:28 Page 190SwitchesA common failing is that switches are not positioned logically in termsof their relation to the fittings and behaviour patterns of occupants.Switches remote from fittings lead to uncertainty as to the status of thelights. The answer would be to include a red ‘live’ light in the switch.Remote infra-red switching is an efficient and effortless system,provided the operation zone focuses down to the size of an individualworkstation. Where switching is not ergonomically appropriate thetendency once again is for lights to be left on permanently.System managementOne major reason why certain high profile energy efficient buildings failto meet expectations is because of deficiencies at the level of systemmanagement. It may be that system interfaces are not well understoodby staff. Even service managers and suppliers are occasionally not aswell informed as they should be. The problem is exacerbated if theoriginal software source is no longer available.System complexity is another problem. If services managers arenot conversant with the intricacies of a system, they will tend to operateit at or near its optimum on the principle that overkill masks lower orderproblems and safeguards one’s back. Also, overcomplex systems dis-courage interference and adjustment in case the outcome is worse anddefies a remedy. Calling out specialists to make adjustments can beexpensive thus tempting managers to prefer to operate the systembelow its design efficiency.Complex systems can also be inflexible. In some cases the system’sprogramme no longer serves the functions of the building. In extremecases this has led to the complete abandonment of the system.In some cases the fault for poor system performance lies with officemanagers who fail to inform the staff of the operational characteristics,cost and energy implications of the system. For example, in oneinstance, staff were not told of the fact that pressing a switch twicewould turn on extra lights. The human factor is of prime importance.Good communication between management and staff can achieve asatisfactory performance from a less than perfect system. Inadequatecommunication can undermine the virtues of the best possible systemdesign.There is also the situation that office managers sometimes fail toaddress the more subtle needs of staff, gearing the system to crudeaverages with the result that nobody is satisfied.The increasing popularity of flexible working hours is causing diffi-culties. Light controls may have been designed for fixed working hoursand set lunch times. This is another instance where the complicationsand cost of modifying the system to respond to new work practices mayLIGHTING – AND HUMAN FAILINGS191AIAC-Ch15.qxd 03/25/2005 17:28 Page 191be unacceptable and therefore the system is abandoned. There hasbeen a case where all lights in an office were operated from a centralcontrol desk. The desk only operated from 09.00 to 17.30 hours. Sincestaff became able to work flexible hours, it meant that those workingafter 17.30 were obliged to leave the lights burning all night.Another potential source of conflict between design and operationis when a single occupancy office reverts to multiple occupancy. It isusual for the principal tenant to have overall control of the services.Variable working patterns and conflicting needs often means that lightsare left on unnecessarily.A relatively recent trend in the production of buildings is for thedesign to be separated from the fitting-out. The architect and servicesdesigner may produce an elegant energy-efficient concept which canbe totally vitiated by the fitting-out contractor who has not beeninformed of the energy saving features and consequent operationalconstraints of the design. Even worse is the situation where the sub-contractor deliberately ignores the design objectives of the architectand engineer in order to keep down costs. The problem of discontinu-ity between design intention and fitting-out can be particularly acute inthe case of refurbishments.Air conditioned officesThese present a different set of problems for designers. The psycho-logical effect of a space hermetically sealed from the outside world is tosuggest an environment designed to overcome nature and be whollydistinct from it. As a result, the inhabitants tend to regard it as naturalthat all the services should be fully used all the time. If, in addition, thefacades feature solar tinted glass, even more lighting is used to com-pensate for the constantly gloomy outlook.Lighting – conditions for successOpen plan installations which offer occupant satisfaction and energyefficiency usually satisfy four conditions:● The design is straightforward and comprehensible, avoiding over-complexity.
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