If your home feels more like a greenhouse than a comfortable home this week, you’re very much not alone.
UK homes have long been designed around one problem: keeping warm in winter. That’s helped with cold rooms and high heating bills, but it also means many homes struggle when temperatures climb well into the 30s.
Climate change is making this harder to ignore. The Met Office says UK summers could be between 1°C and 6°C warmer by 2070 compared with 1990, with the hottest summer days 4°C to 7°C warmer. The Climate Change Committee has warned that hotter heatwaves could leave 92 per cent of existing UK homes at risk of overheating.
That doesn’t mean the answer is to rush out and install air conditioning. For many homes, the best first steps are cheaper, greener and more effective than people realise: keep the sun out, keep hot air out, then let cooler air in when the temperature drops.
Longer term, the trick is to improve your home in the right order, so it becomes cheaper to run in winter, cooler in summer and kinder to the planet.
How to cut energy bills by greening your home
1. Shut the heat out before it gets in
This is the bit many of us get wrong.
When it’s baking outside, opening every window can make your home hotter, not cooler. If the air outside is warmer than the air inside, you’re inviting the heat in.
The NHS advises keeping curtains closed in rooms that face the sun, and the UK Health Security Agency says windows should be closed when the air outside is hotter than indoors.
The simple rule is: keep windows, curtains and blinds closed during the hottest part of the day, especially in rooms that face the sun. Then open windows in the evening, overnight or early morning when the air outside is cooler, if it’s safe to do so.
South-facing rooms can overheat, but west-facing rooms can be particularly bad because they catch the late afternoon and evening sun. That’s often why bedrooms feel unbearable at night, even after the temperature outside has started to fall.
The aim is to stop heat building up in the first place. Close blinds and curtains early, before the room is already hot. If you work from home, move to the coolest room rather than staying in the sunniest one out of habit.
A basic thermometer can help. UKHSA guidance for care settings says rooms above 26°C should be treated as too hot for vulnerable people, including older people, babies and young children, pregnant people, people with heart, lung or kidney conditions, and anyone taking medication that affects how their body handles heat.
2. Use fans wisely
Fans can make a room feel much more comfortable, and they are far cheaper to run than air conditioning. But they don’t lower the room temperature, they cool you by moving air over your skin.
Use them in the room you’re actually in, rather than leaving them running in empty spaces. If the air outside is cooler than indoors, placing a fan near a window can help pull cooler air through the home.
There is one important health warning. NHS heatwave advice says fans should not be aimed directly at your body and may not prevent heat-related illness in very hot rooms. UKHSA guidance also warns that fans become less effective when indoor temperatures rise above 35°C.
For most households, fans are a good low-energy comfort fix. They work best when paired with closed curtains in the day and safe ventilation in the evening.
3. Cut the heat you create indoors
On very hot days, your home doesn’t need extra help getting warmer.
Ovens, tumble dryers, older lightbulbs, chargers, games consoles and appliances left on standby all add heat. Some only add a little, but in a heatwave every bit counts.
This is the week for no-cook dinners, salads, wraps, picky plates, microwave meals or anything that avoids turning the kitchen into a sauna. Dry clothes outside if you can, switch appliances off standby, and charge devices outside the room you’re trying to keep cool.
These small changes also save energy. Energy Saving Trust estimates that avoiding the tumble dryer and drying clothes outside can save around £50 a year in Great Britain, while switching appliances off standby can save around £45 a year.
That’s the sweet spot for sustainable cooling: less heat indoors, lower bills and less wasted energy.
4. Choose shade before air conditioning
Air conditioning can cool a room quickly, and for some people with health conditions it may be necessary. But it uses electricity, costs money to install and can increase demand on the grid during heatwaves.
Before going down that route, look at shade.
Curtains and blinds help, but external shading is usually better because it stops the sun before it hits the glass. The Climate Change Committee’s overheating research found that shading, window film, roof insulation, fans and external shutters can all reduce overheating risk in existing homes.
That could mean an awning, shutters, a shade sail, a pergola, climbing plants, trees or balcony screening. You do not need to do the whole house at once. Start with the room that overheats most, especially if it has south or west-facing windows.
A simple awning over patio doors, reflective film on a problem window, or a planter with climbing plants can make a real difference.
If you’re planning an extension, this is worth thinking about before you build. Big glass doors may look beautiful in spring, but without shade they can make a room miserable in summer. A roof overhang, pergola, tree or external blind should be part of the design, not something you try to fix later.
5. Insulate, but do it properly
Insulation is usually sold as a winter upgrade. It keeps heat in, cuts heating bills and reduces carbon emissions.
It can also help in summer because it slows heat moving through your roof and walls. But there is a catch: insulation must work with ventilation and shading. If heat gets into a well-insulated home and cannot escape, the house can stay hot for longer.
That doesn’t mean insulation is a bad idea. It means piecemeal retrofit can backfire.
The Energy Saving Trust advises taking a whole-home approach to green upgrades, because measures such as insulation, heating, ventilation and solar panels all affect each other.
Loft insulation, cavity wall insulation, draught-proofing, better windows, solar panels and heat pumps all have a role to play in greener homes. But the order matters. Shading and ventilation should be considered alongside insulation, not years later.
For many homes, a sensible path is to start with the low-cost fixes, then look at loft insulation or cavity wall insulation if suitable, then plan bigger upgrades such as solar panels or a heat pump as part of a whole-home plan.
6. Think about solar panels and heat pumps as part of the plan
Solar panels will not cool your home directly, but they can cut electricity bills and reduce reliance on fossil fuels. That can become more valuable if your home uses more electricity in future, for example through a heat pump, battery, electric vehicle or efficient cooling system.
Energy Saving Trust says the average domestic solar panel system costs around £6,100, with payback varying depending on where you live and how much electricity you use at home.
Heat pumps can also cut carbon sharply, especially when replacing oil, LPG or old electric heating. But they need good design, and savings vary depending on the home. Energy Saving Trust’s heat pump guide says they work best in well-insulated homes and need to be properly sized and installed.
The key point is not to buy expensive kit in a panic. Big upgrades should work together, so your home becomes cheaper to heat, easier to cool and lower carbon over time.
7. Make a plan before the next heatwave
Once the weather cools, it’s tempting to forget how uncomfortable your home felt. Try not to.
Walk around and note which rooms overheated, which windows caught the worst sun, whether the house cooled down overnight, and whether you could safely ventilate bedrooms. That gives you a practical starting point.
If money is tight, focus on the hottest rooms first. Better curtains, reflective film, a good fan, draught-proofing that does not block proper ventilation, and outdoor planting can all help without a major spend.
If you have more to invest, look at external shading, loft or cavity wall insulation, solar panels and a proper retrofit plan.
GreenVal can help homeowners compare green improvements by property type, location and budget, including likely costs, benefits, supplier quotes and DIY options. That can be useful if you know your home needs work but are not sure whether to start with insulation, solar, heating or simpler fixes.
