Sat, Aug 03, 2019 page9

• Experts call for ban on glass skyscrapers to save energy

  Air-conditioning is used to avoid a ‘greenhouse’ effect, but cooling buildings adds to carbon emissions

  • By James Tapper / The Observer
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  Leading architects and engineers are calling for all-glass skyscrapers to be banned because they are too difficult and expensive to cool.

  “If you’re building a greenhouse in a climate emergency, it’s a pretty odd thing to do to say the least,” said Simon Sturgis, an adviser to the government and the Greater London Authority, as well as chairman of the Royal Institute of British Architects sustainability group. “If you’re using standard glass facades you need a lot of energy to cool them down and using a lot of energy equates to a lot of carbon emissions.”

  Glass-fronted offices, from high-profile buildings such as the Shard in London to shopping centers and industrial parks, have become popular with architects and their clients because they create an arresting view in a city skyline, let in lots of natural light and provide great views for those inside.

  

  Illustration: Tania Chou

  However, the sunlight also brings heat and in sealed buildings there is nowhere for it to escape to naturally — something which, as Britain sweltered in a record-breaking heat wave, will have become apparent to many working inside them.

  To avoid this greenhouse effect, air-conditioning has been the standard solution, but that is problematic in itself.

  The International Energy Agency estimates that about 40 percent of global carbon dioxide emissions come from constructing, heating, cooling and demolishing buildings. Air-conditioning is a growing proportion of this: Energy used on cooling has doubled since 2000 and now accounts for about 14 percent of all energy use.

  In April, New York City Mayor Bill de Blasio said he would ban all-glass buildings and force developers to retrofit existing buildings to make them more energy-efficient, although the “ban” was later clarified to mean excessive use of glass and steel.

  London Mayor Sadiq Khan has ruled out such a plan for the British capital, but Sturgis believes the American is on the right lines.

  “Certainly, I think there should be a ban,” he said. “The connection needs to be made between the climate emergency and all-glass buildings, but the connection hasn’t been made yet.”

  Mitsubishi Electric head of sustainability Martin Fahey said that higher temperatures meant that air-conditioning machines now needed to work harder than in the past.

  “Most air-conditioning equipment is designed to give an internal temperature between 7 to 10 degrees lower than the ambient temperature,” he said. “I suppose it’s fair to say if that machine is getting old or has developed a fault somehow, Murphy’s law being what it is, something will go wrong and it will fail.”

  The new version of the London Plan, the rules for all development in Greater London, which is due to take effect next spring, requires construction firms to make an assessment of a building’s energy use across its whole life cycle. Sturgis hopes that investors will react more quickly.

  “Big commercial tenants don’t like standing up in front of their shareholders and saying they’re doing embarrassing things,” he said. “No one wants to be treated as ‘Mr Climate-Dirty Building’ and I think this is going to start happening.”

  “I’m advising a bank that wants to build a very big building in London — which I can’t tell you about, but I’m having this exact conversation — I think the building could be obsolete by the time it’s finished,” he said.

  Glass has some advantages: in colder weather, the warming effect of sunshine — “solar heat gain” in the jargon — means less energy on heating.

  Architects can still use this with smaller windows, said Simon Wyatt, a partner at Cundall, an engineering firm, and a UK Green Building Council committee member.

  He said natural ventilation would save “up to 60 to 70 percent on our air-conditioning loads,” but in city centers, air pollution and traffic noise make this impossible.

  Newer buildings use special types of glass that can become more opaque to block sunshine in hot weather, or even generate electricity themselves, such as the Edge in Amsterdam. It uses about 70 percent less energy than most buildings, but is not glass-fronted on all sides — the southern, eastern and western sides have smaller window openings to reduce heat gain and windows that open.

  However, these laminated glass panels still contribute to the climate crisis, Sturgis said, because they are much more expensive to make and almost impossible to recycle.

  “To mitigate the amount of energy used to cool these buildings, you have to produce a really complicated facade, which is usually triple-glazed, but double-glazed units and laminated glass don’t last very long — 40 years or so. So you have to replace your facade every 40 years, that’s also not a very good idea,” he said.
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