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Passivhaus proposed to keep UK homes cooler as summers heat up

newsAug 22, 202630130

On a 35C day in south London Marion Baeli’s retrofitted 1960s ex-council house was about 10C cooler inside than outside, which she credits to the Passivhaus standard. Passivhaus, developed around 35 years ago in Germany, seals and super-insulates homes to keep internal temperatures steady and is estimated to cut energy use by up to 90% compared with typical houses. Baeli, an architect and non-executive director of the Passivhaus Trust, phased retrofit work over ten years at a total cost of about £80,000; she says the new triple-glazed windows cost roughly £30,000 and making the house airtight cost about £5,000. After the works Baeli estimates energy demand fell by 88%, saving nearly £750 a year on bills, and one radiator now heats the four-bedroom home in winter because heat loss is minimal. The Passivhaus Trust accepts retrofitting to this standard is expensive, and the house still depends on cool outdoor nights: when overnight temperatures stayed at 27C the indoor temperature did not fall. More than half of UK homes are already at risk of overheating and, at current climate-change rates, that share could rise to 92% by 2050 if homes are not adapted.

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