In the UK we are used to worrying about our homes being warm enough, but after struggling to cope with high temperatures in May and June the race is on to cool them down before the next heatwave hits.
And while it might be tempting to swap your desktop fan for a portable air conditioner, there are lots of low-cost, more sustainable ways to stop rooms overheating.
Tom Greenhill, an engineer, environmentalist and author of the Heatwave Toolkit website, says: “Air conditioning will cool the privileged but will not work for the many – or the environment.” Even if you do decide to buy an air conditioner, powerful passive measures, such as shading windows, will make it more effective, he says.
Blocking the sun’s heat is vital. “We don’t heat a building without insulating it so why are we cooling a building, whether that’s with a fan or air conditioning, without shading it first?” asks Stuart Dantzic, the British Blind & Shutter Association’s vice-president.
So where should you start? Here are seven ways to stop the sun. Some cost less than a tenner – and are ideal for renters – but others, such as external blinds or awnings, are a long-term, costlier fix.
Start in the loft
To stop overheating, where you put shading matters far more than the product you buy. Shading fitted on the outside of the glass can reject up to about three times more solar heat than an equivalent blind fitted on the inside.
If you want the “biggest bang for buck” cover skylights first as they get direct sun for most of the day.
External shading is far more effective than just closing curtains or an internal blind, Greenhill says.
“My loft is exactly the same as my neighbour’s; we live in a Victorian terrace house and the same person built our lofts to the same standard,” he says. He bought £80 Velux external awning blinds and his space is cooler.
“I looked up the product code for our Velux roof window and ordered the corresponding awning blind. The one we needed was £80. Our roof window is within easy reach, so the cheapest, manual version was viable. I installed it within half an hour of DIY. Now, it takes 20 seconds to deploy or hide away as necessary.”
You can buy the blinds directly from Velux. A manual anti-heat blind promising the temperature will be “up to 4C cooler inside” is £110 for a standard-sized window with delivery in 12-13 working days.
For the company’s more expensive anti-heat blackout shutters that “reduce solar heat by up to 5C indoors” it is £530 on the same basis plus £166 for the electric control. Delivery is in 18-19 working days. You need to pay someone to fit these aluminium shutters.
If money is tight or you are renting, meaning that fitting blinds is not an option, a trip to Ikea to buy a £5 fitted sheet could solve the problem.
Exeter-based Bojana Bajzelj worked out that the skylights in her ground-floor extension were the same size as an Ikea king-size sheet. The £5 Bärglim sheet sits as a top hat over the light and knocks out the solar gain and, because it’s white and translucent, still allows plenty of daylight through. She estimates it is now 2C to 4C cooler in the kitchen, with the added benefit that she no longer has to wear sunglasses indoors.
The cheapest fix is repurposing something you already own, such as old towels, curtains or bedsheets. “These are temporary but very effective measures. Give it a try before you invest in something properly designed for the job.”
Set sail
Large bifold or patio doors have become trendy, but a window behaves like a one-way heat trap, heating up your kitchen or living room. “If your home looks like a greenhouse, it will perform like one, too,” Greenhill says.
But there are some canny solutions to test out before stumping up for external blinds or an awning. If you don’t want to drape an old sheet over your Grand Designs-worthy extension, why not rig up a solar sail? It’s a sturdy stretch of fabric suspended between walls or posts.
Even for the DIY phobic this is doable, requiring some stainless steel eyelets (to bash into the wall), carabiner clips and a sail. He says: “It will be super effective – that’s why you see it in streets across Europe. You can get something that looks really smart and well-designed for about £20.”
You can spend as much as you want on a features like this. Dorset-based Kemp Sails traditionally makes yacht sails but has adapted its skills and sells chic-looking shades through its Shade Solutions arm. Prices start at £136 for a one-metre by two-metre rectangle. For something cheaper, Amazon has a variety of sizes and colours. You can buy a two-metre by two-metre shade for under £20.
The benefit of such an approach – as opposed to sticking a plastic solar-reflecting film on to the glass – is that once winter arrives, you still get the full benefit of the heat and light gleaming through your windows. Most people who use film tend to leave it on all year round.
Rig up a camouflage net
A cheap and cheerful option is a camouflage net. The net can be draped over windows or skylights or used as a makeshift awning or pergola.
They can also be found on Amazon for about £10 and in a variety of sizes and camouflages. It will block out a good proportion of the direct sun while offering you plenty of daylight and ventilation.
You can rig it up with zip ties and, if you double it over, it will block out more of the sunshine. Another useful material is the shade cloth used to protect plants. It is readily available and, because it is a mesh, you can see through it.
Clip shades on sashes
After neighbours with a baby were admitted to hospital with a heat-related illness during the June heatwave, Greenhill suggested they buy Shaded’s £89 mini awnings to clip on to their windows. They are fitted from the inside and adjust to windows of various widths.
The product – the brainchild of company founder Aimée Daniels – has taken off and is now sold out on the Shaded website. However the small business says it will be restocked in a fortnight and is offering 10% off purchases of two or more awnings.
Invest in external blinds
It is probably too late to buy external blinds in time to combat the coming hot spell but that doesn’t mean you shouldn’t invest in them for future summers.
“External blinds and awnings don’t lower internal temperatures, they stop them rising,” says Dantzic, whose day job is running Suffolk-based Caribbean Blinds, the UK’s biggest manufacturer of external shading systems.
“When someone gets home and the property is already overheated, an external blind will stop it getting any warmer.”
He adds: “An external roller blind is very similar to an internal one. It is a different type of fabric but it’s the same principle.”
The cost will depend on the size of the area you want to cover, but for an average set of bifold or patio doors an external roller blind will be in the region of £3,000-£4,000. For an additional £250 Dantzic advises fitting a weather sensor so they are responsive to light levels and close themselves – meaning you can prevent overheating happening in the first place.
“Sensors don’t add a lot of cost but having the blind do what it needs to, when it needs to is worth its weight in gold.”
Awning it
Go back to the Victorian times and shop fronts were shaded with awnings to protect customers from rain and shine, Dantzic says. Unfortunately, more recently buildings have been designed to “keep heat in: lots of glass, airtight, insulated walls and ceilings. Now we’re in a situation where, as soon as that heat’s in the building, we can’t get it out. So on a hot day everyone wants a quick fix and heads to B&Q or Screwfix to grab a fan.”
An awning offers households more flexibility than an external blind. “Because they project out from the facade you can still use your bifold or patio doors,” he says. “You also have the added benefit that they provide an outdoor space that’s in the shade.” However they are more expensive – in the region of £4,000 to £6,000 for a covering to fit a typical set of bifold or patio doors.
Get flash with shutters
Motorised metal shutters or manual wooden shutters on the outside of buildings are a common sight in hotter climates and across continental Europe. In the UK more and more people are asking about them, says David D’Ambrosio, a director of the Scottish Shutter Company, but they are “still not a product that is widely used”. The company sells external aluminium shutters but more usually fits wooden interior ones.
The real choice is not “inside or outside”, it is “how much heat do I need to stop, and how much do I want to spend”. External systems cost more because they work harder, are exposed to the weather, and are motorised. Scottish Shutter Company’s interior wooden shutters start at £550 for a typical 1.2-metre by 1.4-metre living-room window. On the same basis it is £1,100 for external roller shutters or £1,450 for aluminium shutters.
“External products work best when they’re incorporated into the build of the property,” D’Ambrosio says.
He recounts the experience of a customer in Perthshire where the solar heat gain was so high that the plastic coating on their kitchen island was peeling off. They initially wanted to fit something outside “but all the windows opened out and there was no recess … so we ended up fitting internal blinds because it was neater and more cost-effective.”
