From shade to shutters: cooling homes in a warming Europe
‘Air conditioning is the very last and worst solution,’ says one expert
By Sarah Murray
After a hot summer in Europe and in all likelihood a hotter one next year, many people will be thinking about buying air conditioners. But are there more environmentally sustainable — and affordable — alternatives? And what are the technical, policy and market barriers slowing their adoption?
While air conditioning may be unavoidable in some instances, it can also contribute to the problem of overheating. “It’s using a huge amount of energy and that heat’s got to go somewhere,” says Molly Allington, chief executive and co-founder of start-up Albotherm, a University of Bristol spinout that is developing cooling coatings for glass that turn from transparent to white when temperatures rise.
“Air conditioning is the very last and worst solution. There are so many steps in between,” says Thomas Auer, a professor at the Technical University of Munich and an expert in climate-responsive building design.
Some solutions have existed for centuries. Auer points to the ancient wind catchers of Yazd, Iran — tall towers that capture cool breezes from above and draw them down to cool the buildings at ground level — and the courtyards, arcades and external shutters found in traditional cities in southern Spai
Today, a range of measures can be taken, from external shading and tree planting to building designs that allow for cross ventilation. “It’s about understanding the type of home you have and the measures you can take right now,” says Emma Howard Boyd, chair of the UK’s National Heat Risk Commission, an independent body based at the London School of Economics.
She points to the suggestions presented in a guide from Shade UK, commissioned by the British Red Cross. The Overheating Adaptation Guide for Homes offers 43 measures people can take to cool houses and apartments, along with an indication of the relative cost of each.
Some are fairly simple steps, such as turning off heat-generating appliances such as TVs, lights and laptops when not in use. Internal shade can be created by using blinds or curtains or positioning indoor plants by windows to filter sunlight. Covering flat roofs with white solar-reflective paint reduces the temperature in the rooms below by several degrees.
And while they are not effective in extreme heat, ceiling fans enable skin moisture to evaporate faster, dissipating the layer of heat that surrounds the body. “They don’t consume a lot of energy,” says Clément Gaillard, founder of Freio, a French consulting firm specialising in climate-focused design. “And it improves comfort levels because it activates that natural cooling effect.”
Nature can help. Shade UK’s guide offers suggestions such as planting low-growing vegetation on flat or sloping roofs or installing trellises of climbing plants around doors and windows.
Approaches will vary regionally, depending on the local climate and architectural styles. But one solution stands out: using shade. Auer is unequivocal. “Shading, shading, shading. That’s essential,” he says.
“Shading is effective, particularly when it’s on the outside because it stops heat from getting into the building in the first place,” says Allington, whose company has secured seed and grant funding to trial its coatings on commercial buildings and greenhouses.
External shading will be critical given the large amounts of glass used in modern buildings. “The amount of energy that passes through glass is astonishing. So you need to develop outdoor shading systems,” adds Gaillard.
However, while some of the answers to overheating seem straightforward, the technical obstacles are not to be underestimated. Retrofitting older buildings is challenging. Their design and construction may not permit the creation of cross ventilation, for example. And ceiling fans require electrical installation along with a certain ceiling height.
When it comes to external shading, fitting systems to the exterior of existing “glass box” style apartments poses engineering and operational challenges. The systems need to be attached to façades not designed for that purpose. They must open and close and they must withstand weather conditions such as high winds. Meanwhile, most older homes have windows that open outwards, so do not accommodate external shutters.
Planning laws can also slow things down. “Some of the issues we face are around planning permission and making it easier to put things on the outside of buildings,” says Howard Boyd.
Auer believes policymakers should step in, both to speed up adoption and to create a sufficient supply of sustainable cooling products. “If legislation required buildings to have external shading, within a year we’d have amazing solutions,” he says.
Allington argues that, whether it is advancing new cooling technologies or removing planning restrictions, speed is essential. “We need to move a lot faster to make an impact now before it’s too late and people start putting air conditioning into their homes,” she says. “That’s what we want to avoid.”
