Air conditioning in the UK is moving from an occasional luxury to a serious policy question as extreme heat exposes how poorly many British homes cope with summer. Buildings designed to retain warmth can become dangerously difficult to cool, particularly at night, when the human body needs relief from high temperatures.
Cities make the problem worse. Concrete, brick and roads absorb heat during the day and release it slowly after sunset. This urban heat island effect can leave city centres up to 7C warmer at night than nearby countryside.
Researchers at the University of Birmingham modelled an earlier West Midlands heatwave and concluded that the heat island effect alone contributed to roughly half of 130 heat-related deaths. That makes cooling less of a lifestyle discussion and more of a public health issue, inconveniently arriving just as the country is trying to reduce energy use and carbon emissions.
Why British homes stay dangerously hot at night
Jo Shields, head of sustainability at Walsall Housing Group, or whg, says residents repeatedly describe the same problem. The housing association owns 23,000 homes across Walsall and the Midlands.
“The heat gain stays within the concrete or the brick,” Shields said, “so the night-time cooling becomes harder.”
During last summer’s high temperatures, residents at Ellum Pointe, a whg development for people aged over 55, told the landlord they could not cool their flats. The association responded by turning a shared space into an improvised refuge.
“We took the community room, closed all the windows and doors, and we put a mobile air-conditioning unit in there,” Shields said. “And basically, we created an internal cool room.”
She compared the arrangement with the warm spaces opened during the pandemic for people unable to afford adequate heating. Britain has therefore reached the tidy point where communal rooms may be needed for both ends of the thermometer.
Shields previously concentrated on decarbonising the housing stock. She must now balance cutting emissions with adapting homes to temperatures they were not designed to handle. Landlords across the country face the same conflict: spend money reducing future warming, or spend it protecting residents from heat that is already here.
Why climate adaptation receives less attention
Reducing carbon emissions has long been the more investable side of climate policy. Heat pumps and electric vehicles can be manufactured, sold and financed. Shading buildings, improving ventilation and keeping hospitals cool may prevent deaths and reduce future costs, but those benefits are harder to turn into an immediate commercial return.
Baroness Brown, the engineer Julia King and chair of the adaptation committee at the Climate Change Committee, says the imbalance is also built into UK law.
Under the Climate Change Act, the mitigation side of the committee recommends legally binding carbon budgets. Ministers are required to deliver them, and progress is assessed annually. Climate adaptation does not have comparable legal force. The government produces its own risk assessment and its own plans.
“Essentially, the government writes an essay, and our job is to say, is it doing the things it said would do in its essay,” Baroness Brown said. “It’s not actually to say, are these things any good.”
She said the committee has spent “almost 20 years pulling our hair out” over the weakness of the system. This year, it published a report as Britain’s first May heatwave arrived, calling for firm national adaptation targets.
Its modelling found that cooling support for the 30% most vulnerable homes, combined with cooling in hospitals and preventive care visits, could reduce by 40% the projected increase in heat-related deaths by 2050.
Where experts believe air conditioning is needed
One of the Climate Change Committee report’s more contentious recommendations concerns mechanical cooling. Only about 5% of English homes currently have a cooling unit. The committee recommends installing cooling systems in hospitals and care homes within 10 years, and in schools within 25 years.
That marks a shift from longstanding government advice favouring passive cooling. Such measures include:
- External shading and shutters
- Better ventilation
- Reflective roofs and surfaces
- Building designs that limit direct solar heat
- Ceiling fans and other low-energy cooling
Professor Mat Santamouris of the University of New South Wales, described as the world’s most-cited researcher on urban overheating, argues that air-conditioning equipment should remain the final line of defence.
In one of his studies, reflective roofing reduced indoor temperatures from about 43C towards 30C. Ceiling fans, he noted, can improve comfort at a fraction of the cost and energy use of air conditioning.
Santamouris called the construction of unshaded glass towers in cities “crazy” and warned: “We cannot air-condition our way out of climate change.” He also argued that the air-conditioning industry is “extremely powerful” in shaping demand. Passive cooling generates economic activity too, he said, because installing it requires builders, plumbers and other trades.
Why critics want cooling in public buildings
Others argue that Britain’s resistance to mechanical cooling has gone beyond sensible caution. David Lawrence of the Centre for British Progress think tank compares it with insulating a home for winter but refusing to install radiators.
Air conditioning is already routine in many offices, hotels and shops, Lawrence noted, yet it is often absent from schools and hospitals. That is “kind of odd”, he said, because millions of people use those buildings daily and high temperatures have measurable effects on concentration, learning and health.
The dispute is becoming increasingly political. Some London councils apply a planning “cooling hierarchy” that prioritises low-energy measures over mechanical systems. In a small number of cases, property owners have reportedly been ordered to remove air-conditioning units.
The Conservative front bench has described that position as “dark ages” miserabilism, while other MPs and commentators have called for an “air-con revolution”. The terminology is energetic. The electricity required would be energetic too.
Since April, the Boiler Upgrade Scheme in England and Wales has offered £2,500 towards a reversible air-to-air heat pump, which can warm a home during winter and cool it during summer. In practical terms, it is Britain’s first air-conditioning subsidy, although it is presented as support for a heat pump.
The grant is only one-third of the £7,500 available for a heating-only model. Awareness also appears limited: about 45 households claimed the air-to-air grant in its first month, compared with thousands of claims for heating-only systems.
Who is excluded from cooling grants
Support differs across the UK. Scottish homeowners can receive a £7,500 heat-pump grant through the Home Energy scheme, but air-to-air models capable of cooling are not funded. Northern Ireland does not offer a universal household heat-pump grant.
The England and Wales scheme is unavailable to social housing and new-build properties. Critics argue that this excludes many of the residents most vulnerable to overheating.
In Woolwich, south-east London, a resident named Keisha says her top-floor flat reaches 43C during a heatwave. She described the building as “inhumane”. Keisha and about 20 neighbours at Canada Court and Clifton Lodge are taking their landlord, housing association PA Housing, to court over homes they allege are unfit to live in.
Their case highlights the risk of a widening divide. Residents who can afford their own cooling can reduce the temperature inside their homes. Those who cannot may remain in buildings that trap heat, while also experiencing the outdoor consequences of their neighbours’ systems.
Air conditioning does not eliminate heat. It transfers heat from inside a building to the street. Santamouris said his Sydney studies found that this waste heat increased demand for further cooling by about one-third. As more households install units, outdoor temperatures can rise, encouraging still more installations.
How widespread cooling could strain the grid
Demand for air conditioning tends to peak on still, hot evenings. That is also when solar generation fades and wind output may fall, requiring gas-fired power stations to provide additional electricity.
Burning more gas produces further greenhouse gas emissions, adding to the warming that increases demand for cooling in the first place. High temperatures can also weaken electricity supply. Gas turbines lose output as the surrounding air warms, and several UK plants had to reduce output in June.
Despite the costs and environmental concerns, demand for portable air-conditioning units is rising sharply. People living in overheated homes are making immediate decisions about immediate discomfort. National energy strategy is not always the first consideration at 2am in a 40C bedroom.
Both Santamouris and Baroness Brown support a more limited approach: passive cooling first, mechanical systems where they are genuinely necessary, and clean electricity to power them. They also point to the importance of protecting vulnerable people rather than expecting each household to improvise.
France’s deadly 2003 heatwave demonstrated the consequences of failing to identify and support those at greatest risk. The emerging recommendation for Britain is not to cool every home by machine, but to make hospitals, care homes, schools and vulnerable households safer while redesigning buildings and streets to absorb less heat.
What happens if every building installs cooling
Santamouris points to Tokyo as a warning about large-scale dependence on air conditioning. So many systems release waste heat into the city that their exhaust can produce close to 1,000 watts of warming per square metre, comparable with the energy arriving from the sun at midday.
“It’s another sun,” he said. “Another sun.”
London has not reached that level. But Santamouris warned that continuing along the same path could eventually produce similar effects.
For housing providers such as whg, the issue is already practical rather than theoretical. Shields said the temperatures experienced this year and last, and the prospect of them recurring, leave her deeply concerned.
“It’s our survival,” she said. Most days, she tries not to dwell on the implications “because otherwise it terrifies me”.
For now, the cooled community room at Ellum Pointe offers some relief. Resident Mandy said she is grateful to have somewhere cooler to sit with her mother.
“We sit there all day with it on,” she said. “It helps so much I want one in my flat.”
That request captures the central problem. Mechanical cooling can provide fast, meaningful protection. Used everywhere without better buildings, cleaner electricity and careful planning, it can also intensify the conditions that made it necessary.
