Digital editor Matt Brundrett asks the question: When it comes to UK buildings, are heatwaves being forgotten?
It seems an odd question to ask when the UK is on track to see the hottest June on record, and has been in the grip of several record-breaking heatwaves in the past few years.
But still, the policy seems to be aimed at the opposite – keeping homes warm. Is it time to widen the scope?
UK heatwaves are dangerous
As many of us know, the UK has a bit of a stereotypical reputation for being a cold and wet country, with weather conditions being described as anywhere from “temperate” to “miserable.” So one must forgive when those outside of the UK may see the temperatures reached during a heatwave and think “what’s the big deal?”
To clarify then, there are a few factors that make heatwaves in the UK particularly acute; the first of which is humidity. The UK has a consistently high humidity (At the time of writing this, the website Your Weather puts relative humidity in London at 77-80%, with the lowest being in Inverness at 64%) which makes heat more unbearable to deal with. High humidity means heat feels closer, and sweat evaporates much more slowly, making it more ineffective as a human cooling mechanism. This also often leads to less cooling at night time.
Another reason is that we are only just starting to experience heat at this level. Climate change is causing rapid increases in heat, meaning that a country that has culturally prepared and built for temperatures reaching around 24-25°C at most are now faced with temperatures reaching up to 30°C or more, and it is set to get higher.
There are other, more controllable or fixable reasons, though, and that is what we are here to truly discuss. The first is related to that culture of cooler climates – Historically, the UK has designed most of its buildings to keep heat in. Winters have always been colder than summers have been hot, and colder temperatures frequently persist in the Spring and Autumn, meaning that we have to deal with the cold and wet far more often than the heat.
As we have a long-held habit of keeping buildings in use long after they were constructed (as per the Horizon Scanning report last year, 80% of the UK’s national building stock will still be in use in 2050), this means that if left unaddressed, the problem will persist and expand. Many buildings, including homes, become heat traps as they retain heat, and cannot properly vent the heat out, even overnight, meaning the heat simply continues to build up over every hot day.
The British Red Cross supports this, with research showing that 45% of people struggle to prevent their home from overheating in heatwaves. The number rises to 58% for people living in top floor flats. This also extends to infrastructure, transport systems, workplaces, etc.
Furthermore, due to our history of cold weather, air conditioning never really took off in the UK, especially in households. Cooling systems were rarely needed, and even electric fans are only owned by 46% of people, according to the Red Cross.
And that’s just at an individual-home level. On a larger scale, cities often make it even worse, as they are often old and were built up without consideration for high temperatures, leading to the Urban Heat Island (UHI) effect. This is a phenomenon whereby heat is retained by artificial surfaces and released very slowly. In cities, where buildings are packed tightly together, and there are far fewer trees to provide shade, this means that temperatures simply do not drop as fast and rise more quickly than in surrounding rural areas. This can lead to temperatures being up to 10°C higher in cities than elsewhere.
All of this combines to make heatwaves in the UK a particularly dangerous prospect. The Heat Mortality Monitoring Report for 2025 in England demonstrates this, stating that there were 1,504 heat-associated deaths across five heat waves, and that another 1,535 deaths were originally predicted on top of this. Older people are more susceptible, as the highest number of deaths were in those aged 85 or over, and those aged 75-84.
What about policy?
In recent years, discussion of any measures to keep the country cooler have been rather minimal, with focus instead being on keeping homes warm. As mentioned previously, I don’t find this to be unreasonable. The UK faces colder weather far more frequently than it faces warmer weather. Still, with heatwaves posing such a danger and being likely to increase in frequency, some clarity and increased action besides pledges to curb climate change would be nice.
It is a little late to solve this particular issue by preventing climate change, as climate change is already here, and is what is causing the issue. By all means, we must curtail climate change as much as we can, but we must also address the issues that are now present and unpreventable.
In 2024, the Environmental Audit Committee, then chaired by Rt Hon Philip Dunne MP, sent a letter calling for clarity in addressing heatwaves to the then Levelling Up Secretary of State, Rt Hon Michael Gove MP. It details that more than 4.6 million UK homes experience issues with overheating in the summer, and this could rise to affect as much as 90% of homes if global temperatures rise by a full 2°C.
Two measures are outlined to achieve this, including extending Part O of the Building Regulations to cover refurbishments, and increasing green spaces in urban areas, as the simplest means to achieve this.
What can be done?
As I sit here writing this, a complex plan is in the back of my mind to try and keep my home cool. At the back where the sun rises, windows and doors are closed, and at the front, my windows and front door are wide open. I have fans set up in painstakingly chosen locations, across from open windows where possible, pointed upward to encourage pooled warm air on the ceilings to move and be vented out of the windows, drawing cooler air from elsewhere (using concepts such as positive and negative air-pressure ventilation).
Despite these complex measures to try to keep cool, I am sweating. The heat is still barely tolerable. I am dehydrating quickly, and need to periodically stand in front of the fan or splash cold water on my face. Thanks to this, I cannot help but feel that upgrading regulations and increasing green spaces, as suggested by Mr. Dunne, simply will not be enough.
My home is not outdated. In fact, it has recently undergone a retrofit to install insulating external cladding and brand-new windows, utilising government funding under the Great British Insulation Scheme (GBIS). Again, these are government measures designed to keep heat in. In theory, the cladding is also designed to prevent excess heat from penetrating, but how much warmth was entering a home through cavity brick walls anyway?
Do not misconstrue my words – in the other months, when the weather is colder, windier, and wetter, this is simply brilliant. Albeit, the process of having the work done was riddled with issues, and from the very start, the funding for the GBIS is given to energy companies (Octopus, E.ON, etc.) who then have full control over who the funds are allocated to and how much they get, leading to a luck-of-the-draw on getting a quote which can make a difference of thousands. But, I digress.
As of right now, to my knowledge, there is only one government scheme that could help to keep homes cool during heatwaves: The Boiler Upgrade Scheme.
I know that sounds counterintuitive, so bear with me.
The Boiler Upgrade Scheme provides homeowners with a government grant to put towards replacing fossil fuel heating systems with either a heat pump or a biomass boiler. Our concern is with the former of the two.
Despite the scheme very much being advertised as upgrading heating systems in homes (again: Keeping heat in) as the press release itself lists the scheme as part of the Warm Homes Plan, the grant can offer £2,500 towards an air-to-air heat pump.
These particular heat pumps can act as both heating and cooling systems, as they can reverse their flow to extract warmer air from indoors and force it outside, effectively installing a low-carbon heating AND cooling system in one go.
Unfortunately, this is not the most enticing option, as the scheme offers potentially far more for the other options, including up to £5,000 for a biomass boiler and up to £7,500 for either a ground-source or an air-source heat pump.
While obviously it is not possible to list a single option for every building, as different buildings will have their own unique needs, it is this author’s humble opinion that we may well be missing a golden opportunity to kill two birds with one stone here.
If grants focused primarily on installing air-to-air heat pumps where possible (achieved by simply making the scheme more accessible and focusing funds for these heat pumps in particular) then we can both make a huge step towards our country’s net zero targets by minimising the number of fossil-fuel heating systems, therefore continuing pledges to tackle climate change, but also provide relief in the form of an in-built cooling system to tackle heat waves, saving the planet, money, and most importantly, lives, all in one fell swoop.
Perhaps I am missing something, but I do not make this claim without support: In March last year, the National Federation of Builders released a statement shortly after the seventh carbon budget was released, urging for more support to be given to heat pumps.
Rico Wojtulewicz, head of policy and market insight at the NFB, said: “The UK has a blind spot to air-to-air heat pumps. Although civil servants have recently published an excellent report on their benefits, they remain poorly supported in practice. Overheating regulations, which oppose mechanical cooling, even hinder the technology from meeting Building Regulations on heating, cooling, and air quality.
“Given that we have twenty-five times more installers for air-to-air heat pumps than air-to-water, and considering that air-to-air technology is more cost-effective, efficient, and quicker to install, the Government must rethink the approach taken by the previous administration. Increasing electrification means more innovation and naturally assists other policy considerations, such as shifting levies from electric to gas, much easier to implement.”
The civil service report on air-to-air heat pumps in question can be found here. In this report, the conclusion reads: “[…]air-to-air heat pumps have significant potential in the UK market due to their energy efficiency, versatility, and ease of installation. Feedback suggests that systems provide increased levels of comfort, heating properties up quickly, and users are largely satisfied with levels of noise produced. Air-to-air systems can easily be retrofitted into properties, although installation is not challenge-free, as is the case with of other heat pump types, with issues remaining around removal of existing systems, planning requirements and distribution network operator approval. The UK has a large installer base skilled in the installation of air-to-air heat pumps, currently almost entirely focussed on the commercial sector.”
To me, that sounds like a solution just waiting to be implemented.
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