Heat desk · chart page
House overheating in summer: how many homes, and why
House overheating in summer now affects about 12% of occupied English homes, up from 7% in 2019, according to the English Housing Survey for 2024.
By the Cooler Indoors desk · figures checked · 3 charts · sources · methods
House overheating in summer has gone from an occasional complaint to a measurable trend. In the English Housing Survey, the share of occupied homes where people said the place got uncomfortably hot and they could not cool it rose from 7% in 2019 to 12% in 2024. That is about 3 million households.
Source: MHCLG, English Housing Survey 2024 to 2025: weather resilient homes · checked 29 October 2026
How we read this Share of occupied dwellings in England where households reported overheating. Only these two years are published as percentages on a matching basis, so this is not a smooth yearly trend; the 2023-24 survey gave a count (2.9 million) instead.
Show the numbers
| Label | % | Note |
|---|---|---|
| 2019 | 7% | |
| 2024 | 12% | About 3 million homes |
How many homes overheat in summer?
Roughly one English home in eight, on the latest survey. The English Housing Survey 2024 to 2025 report on weather-resilient homes puts the 2024 figure at 12%. The year before, the 2023 to 2024 survey counted 2.9 million households saying their home got uncomfortably hot.
Other estimates run higher because they measure something different. The Climate Change Committee said in 2019 that around 20% of UK homes already overheat even in cool summers, a modelled figure for the whole UK rather than what residents report. The table sets the measures side by side.
| Figure | What it measures | Source and year |
|---|---|---|
| 12% | English households reporting their home got too hot to cool | English Housing Survey, 2024 |
| 7% | The same question, earlier survey | English Housing Survey, 2019 |
| Around 20% | UK homes estimated to overheat even in cool summers | Climate Change Committee, 2019 |
| 7% | Overheating households who said they switch on an air conditioner (not ownership) | English Housing Survey, 2024-25 |
| About 2–3% | UK homes with some form of cooling | DESNZ market report, 2024 data |
Which homes are most likely to overheat?
UKHSA's keep-cool-at-home checklist, part of its Beat the heat material, names the types at higher risk:
- top-floor flats, because heat rises
- homes with windows on only one side, so air cannot flow through
- large east-, west- or south-facing windows with no shading
- homes in dense urban areas
- some highly insulated homes
- homes where window opening is restricted
Several of these overlap in newer city flats: one aspect, lots of glass, restricted openings and a top-floor position. Good insulation keeps heat in during winter, and some well-sealed homes struggle to shed it in July.
What do households do when the house gets too hot?
Most reach for the windows first. Among households reporting overheating, 90% opened windows, 75% closed curtains, blinds or shutters, 59% switched on a fan and 7% used an air conditioner.
On video: Heatwaves: Is your house too warm? 1 in 5 Homes Are Overheating - Experts Warn of Health Risks!
“Heatwaves: Is your house too warm? 1 in 5 Homes Are Overheating - Experts Warn of Health Risks!”, a video from the Loughborough University channel on YouTube. Loughborough University researchers show their matched-pair test houses, explain why heat gets trapped in insulated UK homes with lots of glazing, and test external shading. It is their video, not ours, and it loads from YouTube only when you press play.
Source: MHCLG, English Housing Survey 2024 to 2025: weather resilient homes · checked 29 October 2026
How we read this Share of households who reported overheating and said they switched on an air conditioner. The survey warns this is not the same as owning a unit, so it is not an ownership rate.
Show the numbers
| Label | % | Note |
|---|---|---|
| Private renters | 4% | |
| All overheating households | 7% | |
| Owner-occupiers | 9% | Highest share |
The survey does not explain the gap. One likely factor is that tenants cannot usually fit fixed equipment themselves, which leaves them with portables or nothing. The fuller breakdown of what households do, and which of those steps UKHSA recommends, is on our page about cooling a home cheaply, where each step is matched to official advice.
How hot is too hot indoors?
UKHSA's guidance for health professionals says a cool room should ideally be below 26°C, and it is the clearest indoor figure in official advice. The UKHSA guidance uses it when advising where to move the most vulnerable people during hot weather. We could not confirm any official figure for bedrooms specifically, so we do not quote one.
What does Part O require of new homes?
Approved Document O has applied to new homes in England since 15 June 2022, and it does not cover existing homes. It asks designers to limit overheating with passive measures first and to treat air conditioning as a last resort. In the words of the Part O guidance on GOV.UK, mechanical cooling "is expected to be used only where requirement O1 cannot be met using openings".
Source: DLUHC, Approved Document O: Overheating, 2021 edition · checked 29 October 2026
How we read this These are assumptions used in Part O's dynamic modelling of how occupants open windows, not comfort limits or legal maximum temperatures.
Show the numbers
| Label | °C | Note |
|---|---|---|
| Windows start to open (daytime) | 22° | |
| Upper-floor windows open at night if above (at 11pm) | 23° | |
| Windows fully open (daytime) | 26° | Matches UKHSA's cool-room figure |
Part O also assumes bedroom windows will be shut at night if noise inside goes above 40 dB averaged over eight hours, which matters for homes next to busy roads. A home that cannot open its windows at night loses its cheapest form of cooling.
Can a tenant do anything about an overheating home?
Yes, in some cases. The NHS points out that council environmental health officers can inspect a rented home for health hazards, including excess heat. Tenants can also use the low-cost steps that need no permission, such as closing curtains on sunny windows during the day and ventilating at night.
Heat is also a health risk; UKHSA's death estimates by summer show how large. Whether fixed cooling pays its way is weighed up in the case for and against home AC.
Questions this data raises
Why do new-build flats overheat?
UKHSA lists several risk factors that often come together in new flats: windows on one side only, large unshaded glazing, restricted window opening, a top-floor position and high insulation. Part O now asks designers of new homes to tackle this with passive measures.
Does Part O apply when I extend or renovate my house?
Approved Document O says its guidance applies to new residential buildings only. Existing homes are not covered by it.
Is the 12% overheating figure for the whole UK?
No. It comes from the English Housing Survey, so it covers occupied homes in England only.
Can the council help if my rented home is dangerously hot?
The NHS says local council environmental health teams can inspect a rented home for hazards to health, including excess heat. Contact your council's environmental health service.
Sources for this page
- MHCLG, English Housing Survey 2024 to 2025: weather resilient homes gov.uk
- 2023 to 2024 survey gov.uk
- around 20% of UK homes theccc.org.uk
- UKHSA guidance gov.uk
- Part O guidance on GOV.UK gov.uk
- DLUHC, Approved Document O: Overheating, 2021 edition assets.publishing.service.gov.uk
All checked 29 October 2026. How we choose and read sources: Methods & sources.