Britain's Air-Con Debate: How Should We Handle Hotter Summers?

Mandy Bourne and her 80-year-old mum live in a top-floor flat in the West Midlands, England. Their brick home soaks up heat during the day and releases it at night, making the flat dangerously hot in summer. Mandy has a serious lung condition called COPD, and the heat makes it hard for her to breathe. Her story is one example of a growing problem across Britain as summers get hotter.

Cities trap heat so well that urban areas can be up to 7°C warmer at night than the surrounding countryside. This is called the urban heat island effect, and it can be deadly. Researchers from the University of Birmingham found that during one West Midlands heatwave, this effect may have caused about half of the 130 deaths linked to the heat. Jo Shields, who works for Mandy's housing group, says the walls of brick buildings hold onto heat, making night-time cooling very difficult.

Last summer, Shields' team created a "cool room" by putting a portable air-conditioning unit in a shared community space. It was a quick fix, but it showed how urgently people needed relief from the heat. Now Shields must balance two big goals at once: reducing her buildings' carbon emissions and making those same buildings safe in rising temperatures. This challenge is being felt by housing providers across the whole country.

For about 40 years, wealthy nations focused mainly on cutting the carbon emissions that cause climate change — a strategy called mitigation. Adapting to heat, such as redesigning homes or adding cooling systems, has received far less money and attention. In 2023, $1.8 trillion was spent on mitigation worldwide, while only about $65 billion went to adaptation. Many felt that spending on adaptation was giving up on fighting climate change.

Billionaire Bill Gates challenged this view in a memo last year, arguing that too much focus on temperature targets had taken money away from things that could save the most lives. He said governments should invest in cooling for countries that need it. His words sparked fierce debate — some climate scientists said he was creating a false choice, and some politicians wrongly used his words to suggest climate change was a hoax. Gates insisted he simply wanted money spent where it could reduce the most suffering.

Baroness Brown, who leads the government's climate adaptation advisory group, says the imbalance between mitigation and adaptation is even written into UK law. Carbon-cutting targets are legally required, but adaptation has no such legal force. Her committee released a report in May 2025, right as a heatwave hit Britain, urging lawmakers to set firm adaptation targets. The report found that cooling the 30% most vulnerable homes and hospitals could cut the expected rise in heat-related deaths by 40% by 2050.

The report recommended that hospitals and care homes get cooling units within 10 years, and schools within 25 years. Professor Mat Santamouris, the world's most-cited researcher on urban overheating, argues that machines should be the last option. He found that reflective roofing alone can drop indoor temperatures from around 43°C to about 30°C, and a ceiling fan costs far less than an air conditioner. Others disagree, pointing out that air conditioning is already standard in offices and shops but not in schools or hospitals.

The debate has become political, with some councils ordering property owners to remove air-conditioning units and politicians on the right calling this "dark ages" thinking. Since April 2025, England and Wales have offered a £2,500 grant for a special heat pump that cools in summer and heats in winter. In its first month, only about 45 households claimed it. The grant is also unavailable to social housing tenants — often the people most at risk from heat.

Air conditioning has a hidden problem: it does not destroy heat, it just moves it outside, warming the street and raising demand for more cooling. Professor Santamouris found that in Sydney, this effect increased overall cooling demand by about a third. Cooling also peaks in demand on hot evenings when wind and solar power produce less energy, forcing gas plants to take over and releasing more greenhouse gases. In Tokyo, waste heat from air conditioners adds nearly 1,000 watts of warming per square metre — what Santamouris calls "another sun."

Experts agree that the best path forward is passive cooling first, machines only where truly needed, and clean energy to power them. Most importantly, the most vulnerable people must be protected rather than left to manage on their own. For now, Mandy and her mum spend their days in the cool community room at their building, grateful for the relief it brings. "We sit there all day with it on, it helps so much I want one in my flat," Mandy says.