The author is Adam Vaughan.

A building with shutters outside the windows

In France, shutters are more efficient for cooling than interior shading.


There is a weekly email about solutions to the climate crisis.

The temperature in the UK reached 40C for the first time. This is the hottest country in the world and it raises questions about how people will keep cool in the future. The majority of UK homes are built to retain heat.

The UK has a poor track record when it comes to adapting to climate change. In a country where less than 3% of homes have some kind of portable or fixed cooling system, the UK will have to quickly get a lot smarter at cooling homes.

Why can’t we just fit all UK homes with air con?

The urban heat island effect is one of the reasons. Kevin Lane at the International Energy Agency says that 1885 TWh was used for space cooling around the world in 2020. A tenth of global electricity demand is attributed to airconditioning. It might seem like an easy fix to simply use low-carbon electricity from wind, solar and nuclear power. We don't have a lot of low-carbon electricity grids. Lane says that extra emissions are caused by extra electricity use. He says that you can't just say that renewable energy will fix the problem. peaks in energy demand for cooling tend to coincide with peaks in the maximum output of solar photovoltaic panels on homes.

Mike Thompson at the Climate Change Committee advises the UK government. He doesn't care about electricity supply in the summer when demand is already low. He's worried that air conditioning will make the heat island effect worse in urban areas, with interiors cooling at the expense of warming the streets. He says he would be cautious about that. We want to find a way to get through without airconditioning.

So how should we cool our homes?

Thompson calls it passive cooling, which involves shading and Ventilation. Fan Wang at Heriot-Watt University in Edinburgh, UK, says that external shading would be more effective than closing curtains on the sun-facing side of the home. He says that you need to have external blinds to keep the heat out. One small challenge for the UK is that the country is much windier, so external UK shades will have to be more robust Consultants suggest planting trees in front of south-facing windows that provide free shading in the summer that disappears in the winter.

The sun's energy can be reflected on white roofs. The global campaign to make a million roofs "cool" was launched in 2019. In countries with a higher albedo, initiatives might involve using roofing and wall materials that aren't white, but have a higher albedo. Improving the energy efficiency of UK homes for winter will give more of a buffer against heatwaves in summer.

Wang says that the UK has a naturally windy climate. It can be anything from the basic sash windows seen in Victorian homes to more advanced systems of vent, ducts and fans. It's impractical for some homes to retrofit their Ventilation systems.

What about new builds?

There is a big opportunity here. The UK government has recently introduced a new obligation in building regulations so that overheating must be considered in the design of new residential homes. He says it is an important step in the right direction. Strong building codes are the best way to improve cooling in homes according to Lane. He says that the countries of the Nordic region are seen as leaders.

The kind of heavy, thick-walled buildings you might have seen in southern Europe, where the walls absorb the heat and leave the interior cooler.

One of the biggest challenges will be rethinking windows because of their popularity. Wang says the problem is a lot of caulking. Lane says that in some cases the views may have to be sacrificed so that the north side of the house is the only place where the glass is visible.

What about the environment outside our homes?

In order to keep that heat amplification effect as low as possible, we need to pick up other factors, such as how we design towns and cities using more trees and water. Green spaces such as parks and gardens can make a big difference to the temperature in your area. There are fountains that are more common in southern Europe. Towns and cities may need to be rethought. The UK may need to emulate the sort of narrow streets found in hotter climates, which offer shade for other buildings and the street itself. Cities take a long time to change. We are on time. We have to act now.

We’re still going to need more air conditioning too, aren’t we?

It's probably a possibility. The Climate Change Committee isn't assuming a big take in UK domestic air con, but a report for the UK government expects current demand for cooling to flip from being dominated by non- domestic buildings to domestic ones in decades to come. The homes will use up to 85% of the energy used for cooling by the end of the century. The inequity of how climate change impacts hit is one of the reasons why this will be expensive.

A rise in AC is seen as a quick fix, according to Lane. The rising demand for air conditioning in countries like South-East Asia and North Africa that are already hot, as well as in high-income countries like the UK that are getting hotter, means it's vital that governments establish good regulations. Rules similar to those used for smart charging for electric cars will be put in place to try and keep peaks in energy demand from the cooling units. Some AC systems will switch off before the peak, for example.

Without action, the number of heat-related deaths in the UK will rise from 2500 in 2020 to as many as 7000 a year by the end of the century. Keeping UK homes cool isn't an option we want to consider.

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