Homes in many parts of the world will have to be changed to help residents cope with a hotter climate, a study on the global demand for cooling makes clear. A big expansion in the use of air conditioning could be environmentally ruinous 鈥� but there are other ways to keep homes cooler without increasing energy use.
The study estimates how often helpful interventions, such as additional ventilation or air conditioning, would be needed to keep populations comfortable.
It warns that some northern European countries will see the number of uncomfortably hot days jump by at least 30 per cent if the world overshoots 1.5掳C of warming.
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While nations in central Africa face the highest needs for cooling overall under global warming of 2掳C, the UK, Ireland, Switzerland and Norway will face the most dramatic relative increases in hot days.
These European locations are 鈥渄angerously unprepared鈥� for the cooling challenge they face, according to at the University of Oxford, who worked on the study, largely because their infrastructure and housing stock is built for a cool climate. 鈥淐ountries in the northern hemisphere face one of the biggest adaptation challenges,鈥� she told a press briefing.
But with searing temperatures across southern Europe and the US this week, this isn鈥檛 a problem confined to northern Europe. Homes around the world will need adjusting to cope with more intense heat.
The quickest, simplest solution is to install air conditioning. But this would lead to a huge increase in electricity demand, researchers warn, putting power grids under strain and driving further climate change. 鈥淚f our homes are overheated and the first solution that we run to is air conditioners鈥� that is going to drain our energy systems,鈥� says Miranda.
Passive cooling
A greener solution would be to roll out so-called 鈥減assive cooling鈥� technologies, which don鈥檛 require large energy inputs. at the Middle East Technical University in Cyprus looked at the most effective of these options for .
His focus was the three-bedroom, semi-detached , a concept home built in 2015 on the Building Research Establishment campus in Watford. This was designed as an affordable, modular property that minimises heating demand. But the property posed a 鈥�severe overheating risk鈥� during the summer, says Ozarisoy.聽鈥淚 lived in this property for almost seven weeks during the long-term heatwave of summer 2018,鈥� he says. At points, he says, 鈥渕y bedroom temperature at nighttime was 33.5掳C [92掳F]鈥�.
Using computer models of the house to test the impact of different interventions, that adding a windcatcher, a type of ventilation chimney commonly installed in homes across the Middle East, was the most effective intervention for reducing indoor temperatures. Windcatchers catch the cooler breeze from high above the ground and direct it into the building, pushing out the warmer air inside the house. However, although windcatchers could be easily integrated into new-build homes, retrofitting them is likely to be complex and expensive.
Other impactful 鈥� and easier to retrofit 鈥� changes include installing external shutters and shading to windows and doors, which helped to bring the temperature of the 脺蝉别谤丑耻耻蝉 living room and bedroom down to manageable levels, and redesigning the kitchen and living area to create an open-plan layout with better ventilation, which cooled the kitchen by up to 5掳C.
Green technologies also need to be installed thoughtfully, says Ozarisoy. Where possible, solar panels should be installed on the roof of unoccupied buildings, such as garages, since they can warm up in the sunshine then 聽Meanwhile, placing battery storage devices in garages or in attics, rather than in cupboards inside the house, prevents them from pumping extra heat into the home.
Overall, adding external shutters and shading is the single most effective measure to make existing homes better able to cope with hot days, says Ozarisoy.
Immediate solutions
Households in the grip of a heatwave can take immediate steps to make their home cooler, without spending any money. A by Alexandra Rempel at the University of Oregon and her colleagues showed that opening windows at night and pulling down shades during the day can lower peak indoor air temperatures by 14掳C during a heatwave.
鈥淢ost heat in a home comes from two sources: first, people, lights and electrical appliances and equipment, and second, solar heat gain through windows,鈥� says Rempel. 鈥淗ot outside air is actually a very small source.鈥�
Blocking sunlight from entering the home is therefore an effective strategy for keeping temperatures under control. External shutters and awnings work best, but internal blinds fitted with side tracks also help to a degree, she says.
As night falls and temperatures drop, windows should be opened to allow cool air to circulate. If necessary, new windows and security systems should be installed to allow this. 鈥淭he important thing is to open up the entire house at night; to open the windows as soon as outdoor air is cooler than indoor air, and to leave them open all night until the next morning, closing them only when the outdoor air begins to approach the indoor air temperature again,鈥� says Rempel.
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