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only 5 000 large buildings , “ I can deal with that if I am a city ,” he said . Cities should require dramatically reduced emissions from these buildings and tie these requirements to the buildings ’ capital improvement cycles .
Major renovation projects can invest in changing the windows , for example , and use the resulting efficiency gains to downsize the heating and air conditioning system , saving money . Lawrence Berkeley National Laboratory is working on thin , triple-glazed windows that reach R-8 to R-10 levels of insulation . Crown Electrokinetics has developed a window insert that can respond to temperature by blocking or allowing light . This market is growing . View , Inc ., Heliotrope Technologies , Kinestral Technologies and Saint-Gobain are among those operating in the smart glass sphere .
“ There are [ many ]... ways to prevent emissions when you retrofit a tall building ,” said Cathy Higgins , research director with the New Buildings Institute in Portland , Oregon . Besides the obvious – LED lights and heat-pump-based heating and cooling – she cited heat-pump water heaters and ice chilling .
Cities and states across countries like America , are hardpressed to find methods like these to reduce the cost of ambitious building efficiency mandates . New York City ’ s Local Law 97 requires its 50 000 largest buildings , almost all those over 25 000 square feet , to cut carbon emissions by 40 % by 2030 and by 80 % by 2050 . President-elect Joe Biden ’ s Build Back Better plan further calls for upgrading of 4 million buildings to meet targets .
Whether height is paramount for reducing the climate impact of buildings depends on who you ask . Curcija pointed out that elements of a building ’ s skin , like high-efficiency windows — or , perhaps , building-integrated photovoltaics — could make up for tall buildings ’ gravity-driven inefficiencies .
Katrina Fernandez Nova at Adrian Smith + Gordon Gill architects says their research findings on different height configurations did surprise them and have “ shifted our focus at the firm to how we can reduce the embodied carbon of the materials ”.
Ann Edminster asks , “ Is the net effect of allowing taller and taller buildings serving or destroying your efforts at carbon reduction ?” She predicts that the best height for buildings ultimately will be determined to be in the six- to -12 storey range . Since we are still loading the atmosphere with vast amounts of heat-trapping greenhouse gases , the answers are urgent . RACA
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Typically , glass windows insulate only one-fifth as well as the worst wall material .
www . hvacronline . co . za RACA Journal I January 2021 21