If this summer is already teaching us anything, it’s that what once felt exceptional is fast becoming ordinary. Thirty-six degrees in Britain used to make headlines around the world. Now it barely raises an eyebrow before someone remarks that next weekend could be even hotter. Whether we like it or not, our homes are being asked to cope with a climate they were never designed for. Unfortunately, such heatwaves are less temporary inconvenience than a glimpse of our future.
There’s an irony here. British homes have long been among the draughtiest and least energy-efficient in Europe. We’ve spent decades pouring energy into keeping them warm in the winter, only to discover that they’re not even very good at keeping us cool in the summer! The result? Sleepless nights. Stuffy bedrooms. Fans whirring uselessly in corners. Living rooms that become unbearable by late afternoon. And this is important as when we’re too hot, we sleep less deeply. We become more irritable. Concentration suffers. Recovery slows. Even our appetite and motivation begin to change. The house isn’t simply uncomfortable; it’s actively influencing how we think and feel — remembering that our homes are not passive backdrops to our lives, they are active participants in our health.
The good news is that staying cooler doesn’t necessarily require expensive air conditioning or a major renovation. In fact, some of the most effective measures cost little or nothing at all. Others are affordable upgrades that you can take with you if you move. But, if you are planning to renovate, there are now proven ways to create a home that feels comfortable in both January and July.
The real shift I’ve realised though is understanding how heat behaves inside a home. Once you get that, your house can begin to feel less like something happening to you, and more like something you can work with.
Let’s start with the quickest wins.
Cool yourself before you try to cool the room
When temperatures climb into the thirties, the priority isn’t immediately lowering the temperature of your whole house, it’s lowering your own body temperature, to change how you experience a hot house.
Running your wrists and forearms under cool water works because major blood vessels pass close to the skin here, helping to carry cooler blood around the body. Cooling your feet can have a similarly rapid effect.
If you’re struggling to sleep, a lukewarm shower before bed is also often more effective than an icy one. Counterintuitively, a cold shower might feel instantly refreshing, but because it causes your blood vessels to constrict, it can make it harder for your body to lose heat afterwards. Whereas lukewarm water encourages your core temperature to fall naturally, which is exactly what you need before bed.
Cotton or linen sheets also make a noticeable difference, allowing heat and moisture to escape far more effectively than synthetic fabrics. Some people swear by freezing pillowcases or a hot-water bottle filled with iced water. Try it before you eye roll!
Understand where the heat is actually coming from
Most people imagine heat simply seeps in through the walls. In reality, the overwhelming majority of unwanted summer heat enters through your windows. Once it passes through the glass it’s absorbed by floors, furniture and walls, which then slowly release that heat back into the room. This is known as solar gain, and it’s why conservatories can become almost unbearably hot.
But not all windows contribute equally. East-facing windows catch the gentler morning sun. North-facing windows receive very little direct sunlight. The biggest culprits are south-facing windows, which receive the greatest amount of sunshine throughout the day, and west-facing windows, where the low afternoon sun pours directly into rooms just as outdoor temperatures are peaking.
This is why so many living rooms become uncomfortable at exactly the time you most want to use them. But pulling curtains closed after the room feels hot, doesn’t help because much of the damage has already been done. Stopping the sun outside is always more effective than trying to deal with the heat once it’s inside. Which explains why Mediterranean homes use shutters, deep balconies, pergolas and awnings so extensively.
Without these, the trick is to close curtains or blinds before direct sunlight reaches the window. It may feel a bit nuts on a glorious sunny day, but the coolest houses are the ones that deliberately keep the sun out during the hottest hours.
Open the windows, but only at the right time
When it’s 34°C outside and 27°C inside, opening every window simply allows hotter air to flood inside. Instead, keep windows and curtains closed through the hottest part of the day. Then, as soon as the outdoor temperature falls below the indoor temperature during the evening, open windows on opposite sides of the house to create cross ventilation. Leave them open overnight too where it’s safe to do so.
This process, sometimes called night purging, flushes out the heat that’s built up inside during the day, allowing your home to start the following morning much cooler. Think of it as like pressing reset every night.
Why a fan isn’t really cooling your room
A huge misconceptions is that fans cool the air. They don’t. What they do is move air. And as the air passes across your skin it speeds up the evaporation of sweat, allowing your body to release heat more efficiently. That’s why a fan can make you feel dramatically cooler even though the room itself hasn’t changed temperature at all.
However, once the air temperature climbs above your body temperature, you’re just blowing hot air around. That’s why so many people reach the end of a heatwave complaining that their fan “isn’t working”. In reality, it’s doing exactly what it’s always done; it’s just reached the limits of what moving air alone can achieve.
Instead, use your fan strategically. Wait until the outdoor temperature has fallen below that inside your home—usually later in the evening or overnight—then open windows on opposite sides of the house to create cross-ventilation. Position a fan in one of the windows, facing outwards (set back by around 30–90 cm), so it blows the warm indoor air outside. As that hot air is expelled, cooler night air is drawn in through the windows on the opposite side of the house, flushing out the heat that’s built up during the day.
The goal isn’t constant ventilation. It’s ventilation at the right time.
Your loft may be the hottest room in the house
On a hot sunny day, roof surfaces can become dramatically hotter than the surrounding air. The loft above your ceiling effectively becomes a huge reservoir of stored heat, which then radiates back downwards throughout the afternoon and evening. That partly explains why upstairs bedrooms often remain unbearably warm long after the sun has set.
Good loft insulation helps, but ventilation is equally important. A well-ventilated roof space allows much of that accumulated heat to escape before it reaches your living spaces. If you’re renovating, it’s also worth thinking about roof colour. Dark roofs absorb considerably more solar radiation than lighter ones.
It’s not just the weather heating your home
Everyday items in your home generate surprising amounts of heat. From the obvious of ovens and grills, to tumble dryers, dishwashers, halogen spotlights and older incandescent bulbs. Even computers and televisions.
During a heatwave it can be worth delaying laundry until evening, cooking outdoors (or batch or slow cooker cooking first thing) if possible, switching off unnecessary electronics and replacing older lighting with LEDs, which produce far less waste heat. Every little reduction helps.
Why 30°C sometimes feels worse than 36°C
Temperature tells only half the story. Humidity is just as important. Your body cools itself primarily by evaporating sweat. When the air is already full of moisture, that evaporation slows down, making it much harder for your body to lose heat.
This is why a humid 30°C day can often feel more oppressive than a dry 36°C. It’s also why moving air with a fan feels particularly effective when humidity is moderate because it helps sweat to evaporate more quickly.
Small investments that make a surprisingly big difference
If you’re able to spend a little money, there are several upgrades that can dramatically improve comfort without committing to a major renovation. One of the most effective is external shading, as already mentioned. That’s why countries accustomed to hotter climates have relied on them for centuries. External shutters, awnings and external blinds being the gold standard.
If you’re renting, don’t assume these options are off limits. Temporary awnings, tensioned shade sails and removable exterior blinds can often be installed without permanent alterations and packed up when you move. Even a light-coloured sheet hung outside a south-facing window will outperform thick curtains inside.
Cellular, or honeycomb, blinds are another clever option. Their pocketed construction traps a layer of air, helping to slow the transfer of heat through the window. They’re not as effective as stopping the sun outside, but they perform considerably better than many standard roller blinds.
Reflective window films can also reduce solar gain, particularly on south- and west-facing windows. They’re rarely invisible though, so they’re not for everyone, but if overheating is a persistent problem they can make a noticeable difference.
Finally, if you’re considering portable air conditioning, I’d suggest it only as a last resort rather than a first purchase. Why? Because although they genuinely lower the room temperature, widespread AC simply shifts heat outside while increasing electricity demand, alongside creating noise and the practical inconvenience of venting hot air through a window. That said, there are circumstances where it’s entirely justified. If a bedroom regularly reaches uncomfortable temperatures and heat is affecting your sleep, health or recovery, a portable unit may be a sensible investment. Sometimes practicality has to trump perfection.
The changes you make once, and benefit from for decades
The long-term answer to rising temperatures of course isn’t simply more powerful cooling. It’s better building design. For decades we’ve understandably focused on making our homes warmer. The next challenge is making them resilient enough to remain comfortable in both winter and summer, without relying on vast amounts of energy in either season. This is where insulation takes on a different role.
Let's learn about... Insulation (Part 1)
Part of my Cleanest Greenest Home Series: demystifying eco upgrades, healthier materials, and smarter ways to live well inside the homes we already have.
Most of us think of insulation as something that keeps heat in. Certainly for my retrofit that was my priority: a cosier home that used less energy. But it’s been quite the revelation to discover that the wood fibre insulation I chose is also remarkably effective at slowing heat moving in the opposite direction.
In other words, rather than allowing the heat of the day to pass quickly through the roof and walls, it dramatically slows that movement. By the time much of the day’s degrees would otherwise have reached indoors, the outdoor temperature has already begun to fall. As a result, my house simply doesn’t experience the same rapid build-up of heat (thermal lag), and it’s one of the reasons traditional buildings with thick masonry walls often also feel surprisingly cool on hot days. They absorb and release heat slowly rather than responding instantly to every change in the weather.
What’s fascinating is that I’m experiencing a real before/after live experiment because only half of my home has been done so far. When I move from a room with uninsulated walls and an exposed roof to one either with insulated walls and a room above (so protected from heat gained through the roof); or insulated walls alone, the difference is palpable.
But the biggest thing I noticed was the difference the secondary glazing made. When our newly insulated bedrooms were awaiting the glazing to be installed, the gain through the windows, even with curtains drawn, despite the wood fibre insulation, was significant. Again, originally my thinking behind the secondary glazing had been primarily about noise reduction and minimising energy loss/improving comfort through winter. Nonetheless I’d been encouraged to specify something called K-Glass, and that’s what really made the difference in the summer.
Quick explainer: K Glass has an almost invisible microscopic metal oxide coating on one surface that reflects long-wave heat (infrared radiation) back towards where it came from, while still allowing daylight to pass through. So in winter, it reflects heat generated inside your home back into the room, reducing heat loss through the window. And in summer, it helps to reduce the amount of heat transferred through the glazing. Albeit its primary job is thermal insulation rather than solar control. For pure solar control you need Solar control glass which is specifically designed to reduce solar gain by reflecting or absorbing a proportion of the sun's energy before it enters the building. Best for large south- or west-facing glazing.
The temperature in the rooms now with wood fibre insulation and secondary glazing is noticeably more stable in temperature which means I can keep the house sealed during the hottest hours, then deliberately ventilate when conditions outside become favourable. Essentially what’s keeping us cool when it’s hot will also keep us warm when it’s cold. Which is exactly what good aka a healthy building fabric should do.
Perhaps the biggest lesson, though, is how climate resilience isn’t usually created by one expensive purchase. It’s the cumulative effect of many thoughtful decisions working together. But ideally not by filling every room with air conditioning, but by learning from countries that have lived with heat for generations. By understanding shade before machinery. Ventilation before gadgets. Building fabric before quick fixes. In other words, by designing homes that work with the climate we have now, not the one we remember. Because the future of a healthy home isn’t simply one that keeps us cosy in the winter. It’s one that helps us stay well all year round.
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I know from my own experience that good insulation works to keep a property warm in winter and cool in summer. Having undertaken lots of measures to make my 1930s built bungalow more energy efficient in winter the bonus has been how comfortable it has been indoors during these recent heat waves and how cool it feels compared to the temperature outside. I added 50 mm of external insulation on to the filled cavity walls of my detached bungalow, which has many south west facing windows. The insulation was covered in a very light coloured render. I also had triple glazing and very well insulated external doors installed. This was a major investment but worth it because the benefits are being felt all year round. During the extreme heat I keep the windows and doors closed and blinds down. There has been no need for fans or any other measures or purging the heat out later in the day. If heatwaves are going to become more frequent the design of all new properties needs to take this into account now rather than needing to retrofit at a later date, particularly those with large amounts of glazing.
This all makes perfect sense but it needs to be filtered through quickly to the builders who are still throwing up houses in the old style with what appears to be very little regard to the changes in our climate!