Environmental (Commonwealth Union)_ An alarming transformation is taking place in the UK one that is being felt not in the open fields or crowded streets, but behind closed doors, inside the homes of millions. In the span of just a decade, the number of British households suffering from overheating during summer months has surged fourfold, now affecting a staggering 80% of homes. What was once a rare discomfort has become a widespread crisis, with deadly consequences.
This dramatic shift, revealed in a new study published in Energy Research & Social Science, comes at a time when the UK and the world are grappling with escalating temperatures driven by climate change. With record-breaking heatwaves, including the first-ever 40°C day in 2022, the toll on human health is mounting. According to the UK Health Security Agency, more than 10,000 people have lost their lives due to extreme summer heat between 2020 and 2024. Behind these numbers are hidden tragedies: strokes, heart attacks, and respiratory failures quietly accelerated by rising temperatures.
Dr. Mehri Khosravi of the University of East London, who led the research, described the findings as “shocking.” Her study showed that overheating isn’t just uncomfortable it’s becoming deadly, and many still underestimate the risks. “People in the UK often associate warm weather with leisure beaches, barbecues, holidays. But that cultural perception is part of the danger,” she explained. “We need to start seeing heat as the hazard it really is.”
The study, which surveyed nearly 1,600 households, compared data from 2011 to 2022, revealing a steep rise in overheating complaints. While only 18% of respondents in 2011 experienced uncomfortable indoor heat, that figure skyrocketed to 80% by 2022. One-third of participants said their homes overheated daily during the summer, and nearly one in five experienced this discomfort five to six times a week. People frequently reported symptoms like poor sleep, headaches, fatigue, and reduced work productivity—all serious impacts that undermine quality of life and public health.
Alongside this rise in overheating is an equally stark increase in the use of air conditioning, which has jumped sevenfold in just over a decade. Now present in 21% of UK homes, this rapid adoption comes with its complications. While air conditioning offers immediate relief, it also adds strain to the national energy grid, increases carbon emissions, and deepens social inequalities, particularly as lower-income households often cannot afford installation or higher electricity bills.
Khosravi pointed to a critical irony: the very homes celebrated for their energy efficiency—those rated EPC bands A and B—are among the most vulnerable to overheating. Built for insulation and airtightness to reduce heat loss in winter, many modern buildings lack adequate ventilation or passive cooling mechanisms, effectively trapping heat inside during hotter months. Even the simple act of opening windows, a common instinct in warm weather, can worsen the problem if done at the wrong time of day.
Regional disparities also emerged. London, the southeast, and the northwest reported the highest levels of overheating, while the northeast, Wales, and Scotland were less affected. Low-income households were more than twice as likely to report overheating, often due to lack of control over their living conditions, especially renters who cannot make structural modifications to improve ventilation.
Despite the growing evidence, the response from policymakers has been sluggish. Many have criticized the UK’s 2023 climate adaptation plan for its weakness and lack of focus on rising heat threats. Khosravi even recounted speaking with a policymaker who dismissed the problem entirely, claiming, “We only have one month of summer. Why should we worry?”
However, the data presents a different picture. The UK recorded one of the highest rates of heat-related deaths in Europe in 2022, and unless significant action is taken, this trajectory will only worsen. While building regulations were updated in 2021 to include passive cooling strategies like window shutters and shading, they only apply to new construction. No comprehensive studies have assessed whether these changes are effective or widely implemented.
Public awareness also lags far behind. According to the study, half of those surveyed admitted they had little or no understanding of how to stay safe in extreme heat. Most relied on instinctive measures like wearing light clothing, taking cool showers, and drinking cold beverages. However, without broader education and clearer guidance, especially around what heat warnings actually mean, many remain at risk.
Experts like Bob Ward, chair of the London Climate Ready Partnership, argue that a national retrofit programme is urgently needed. This would prioritise vulnerable communities and homes most at risk in areas like London and the southeast. “We need to improve ventilation and cooling without falling into an overdependence on air conditioning,” Ward said. “The government must act, before this silent crisis claims more lives.”
As the planet warms and British summers continue to shatter previous temperature records, one thing is clear: the UK can no longer afford to treat heat as a seasonal nuisance. Heat poses a deadly and systemic threat that is already permeating our homes, infrastructure, and national consciousness.
