UEL study finds 80% of UK homes overheat in summer

The research, published in the journal Energy Research & Social Science, was spearheaded by Dr Mehri Khosravi, a leading expert in climate-responsive design at UEL’s Sustainability Research Institute (SRI). The findings come amid increasing summer heatwaves and record-breaking global temperatures.

“The scale of this rise was a shocking result,” said Dr Khosravi. 

Over the heatwaves experienced in 2022, we had nearly 4,500 excess deaths in the UK - but this mortality is often hidden in statistics about heart attacks, strokes, and respiratory conditions.”

The study, based on a national survey of nearly 1,600 households, was prompted by the 2022 heatwaves, when UK temperatures exceeded 40°C for the first time on record. Alarmingly, more than a third of households reported daily overheating, and over half experienced sleep disruption due to heat. A quarter of respondents cited frequent headaches and fatigue - some even had to reduce their working hours.

As well as overheating, the research also found a sevenfold rise in air conditioning use, now installed in more than 21% of UK homes. Dr Khosravi cautioned this trend could worsen social inequality and strain the national energy grid, especially as families with lower incomes may be unable to afford cooling solutions.

“British homes are designed to retain heat, not lose it,” said Dr Khosravi. “Even the most energy-efficient buildings - those rated EPC A and B - are twice as likely to overheat without adequate ventilation according to the results. This is not just a building design issue; it’s a public health issue, and a behavioural one too.”

The study highlights that overheating is not limited to specific types of housing. Whether living in a detached house or a city flat, households are now struggling with summer heat - particularly in London, the South East, and North West regions. Lower-income households, especially those in rental properties, are more than twice as likely to report regular overheating.

UEL's research also uncovered a huge gap in public understanding of how to cope with extreme heat. Half of respondents admitted to knowing little or nothing about how to stay safe during heatwaves, and many resorted to ineffective methods such as opening windows during the hottest parts of the day.

“We urgently need to improve overheating risk communication strategies,” said Dr Khosravi. “Currently, weather warnings rely on only colour codes, but many people don’t know what ‘red’ or ‘amber’ actually mean for their health or what actions to take.”

With more than 10,000 heat-related deaths in the UK from 2020 to 2024, and projections pointing to even hotter summers, experts agree that urgent action is needed.

“We’re facing a real crisis,” said Dr Khosravi. “Adapting our buildings is vital - but equally, we need to adapt our behaviours and attitudes towards heat. In the UK, people often see hot weather as something enjoyable. But when it becomes extreme, it can be deadly.”

As policymakers debate next steps, UEL continues to play a critical role in shaping research, informing public policy, and supporting communities in adapting to the realities of a changing climate. 

For more information on UEL’s work around sustainability and related research, take a look at the Sustainability Research Institute (SRI) – a centre of excellence in environmental research and development.