WITH the weather heating up, the internet is full of tips and tricks on how to keep your house cool – but do they actually work?
The Sun tried out five popular DIY tricks for cooling your home – and then used a thermal camera to see how well they worked.
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We wanted to find out if they will save you money on energy by stopping you from turning up your fan or using air con.
According to the Energy Saving Trust, using a fan for 12 hours costs between 10p and 20p, while using a portable air conditioning unit costs around £3 for 12 hours, based on the current energy price cap.
Over a summer, from 1 May until 31 August, using air con every day could cost up to £370, while using a fan for 12 hours per day would cost around £25.
For the tests, we used a FLIR ONE Pro Edge, which clips onto a normal smartphone and turns it into a sophisticated heat-detecting camera.
It shows the hottest areas inside the home as yellow, while warm areas are orange and pink. Any places where hot air is escaping outside are shown as dark blue.
The camera also measures the surface temperature of the areas we pointed it at – meaning we could calculate exactly how well the hacks worked.
We asked Phil Steele, future technologies specialist at Octopus Energy, to give his verdict on our results:
Put ice in front of your fan
Fans move air around the room – this helps sweat to evaporate and means you stay cool.
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Some people advise freezing an old plastic bottle full of water and then placing the ice bottle in front of the fan. The theory is this makes the air feels colder without you having to turn up the power.
We found this trick created a cool crisp feel in the air – like turning on air con.
But Phil Steele says the actual difference in temperature will be minimal.
“You may end up generating more heat – and spending more on energy – from the extra work your freezer has to do to freeze the water bottle,” he warns.
- Temperature before: 24.3C
- After: 23.3C
- Change: -1C
Cover your windows with tin foil
We tried out this cooling trick on windows which got direct sunlight in the afternoon.
The thermal camera showed that, before the foil was added, the area right next to the window was a sweltering 29.9C.
Using a £1.75 extra-wide roll of tin foil, we cut a piece to fit the window and stuck it in place by placing a few drops of water on the back. The water makes it stick to the glass.
Adding the tin foil instantly made the window area feel cooler – and the thermal camera showed the temperature dropped by 3.5C.
But we didn’t rate tin foil as a permanent solution on hot days as it blocked out the light, looked messy and reflected light into the neighbours’ windows.
Phil says: “The foil will reflect heat but it’s not a practical solution if you want to look out of your windows.”
Instead, he recommends using blackout curtains, which will also reflect heat back outside.
“Keep the windows and curtains closed on the sunny side of your house to avoid letting heat in, and open them on the cool side to let hot air escape,” he adds.
- Temperature before: 29.9C
- After: 26.4C
- Change: -3.5C
Open your loft hatch
“There is a myth that if you open your loft hatch, hot air will go up into it because hot air rises,” says Steele.
“But actually, hot air moves to cooler areas – and most of us have hotter lofts than the rest of our house. So if you open the loft hatch, you may find hot air just comes down.”
Our test loft was even hotter than a typical one because it had Velux windows which let heat in.
And when we opened the hatch, the thermal camera showed the hatch area was much hotter with it open than shut.
The area around the loft was pretty much the same temperature, at around 25C – it didn’t cool down.
- Temperature before: 27.1C
- After: 31.7C
- Change: +4.6C
Use Victorian air-con
Victorian sash windows were designed to open at both the bottom and top, letting hot air out the top and cooler air in through the bottom.
“Heat rises, so if you open the top of the window you create a chance for heat to escape,” says Phil. If you can only open one edge side at a time, he recommends opening the top.
The thermal camera showed this in action, with the dark blue area on the images clearly showing the biggest amount of heat was being lost through the top opening.
When only the bottom of window was open, the air at the top of the window was a stifling 31.7C.
But with both the top and bottom open, the temperature dropped dramatically to 25.3C.
- Temperature before: 31.7C
- After: 25.3C
- Change: -6.4C
Take a cold water bottle to bed
If you’re hot when you get into bed, a cold or frozen ‘water bottle’ could chill your sheets, helping you keep calm and cool at bedtime.
We used a £2.99 ice pack – but you could simply fill a hot water bottle with ice cubes and a bit of water – which we wrapped in a tea towel and placed under the covers.
As the pack was small, we moved it around after a few minutes to different spots on the same side of the bed.
The dark blue spots picked up by the thermal camera showed exactly where the cool pack had been – and showed it was much warmer on the other side of the bed where the cool pack hadn’t been placed.
But the benefits didn’t last long, as soon the area started to warm up again soon after we moved the pack.
“Unlike a hot water bottle, which will be around 30C hotter than room temperature, a cold water bottle will only be about 15 to 20C cooler than the bed, so it won’t be such a big effect,” explains Phil.
“Also, a hot water bottle cools down gradually and your body temperature helps to keep it warm. A cold water bottle warms up quickly and your body temperature will heat it up even quicker – so any positive effects won’t last long.”
He also warns the cold water bottle will create condensation, which could make the bed “soggy”.
- Temperature before: 25.8C
- After: 20.5C
- Change: -5.3C
What should you do to keep cool?
Phil recommends putting up blackout curtains (you can buy these from £15 at Dunelm and Curtains Direct) and drawing them in rooms facing the sun.
Keeping windows in direct sunlight shut also helps prevent heat from getting in, while opening windows and curtains on the other side of the house helps hot air escape.
Swap which windows and curtains you open as the sun moves around during the day.
“Making sure your walls and roof are well-insulated will also keep heat out, as long as you’re not letting it in through the windows,” Phil says.
This is because insulation works like a thermos flask, keeping heat out in summer as well as keeping heat in during winter.
Using these tricks with a low energy fan could cost as little as 10p per day – 30 times cheaper than using air con.
