How to keep your home cool in hot weather

Typical cost for 24 hours of continuous use: £0.03 – £0.07

Using a fan can be an inexpensive way to keep cool in hot weather. Rather than cooling the air directly, fans create air movement that helps sweat to evaporate, keeping you cool. 

More expensive tower, desktop and pedestal fans aren’t necessarily more efficient or cheaper to run than cheaper models. Bladeless fans, which are often the most expensive to buy, have similar running costs to other models. So, the type of fan you choose largely depends on personal preference. 

Due to their low energy use, fans have minimal CO₂ emissions.

Top tip: using a small USB fan on your desk can be a cheap way to stay cool while working at a computer.

Typical cost for 24 hours of continuous use: £1.12 – £1.30

Like fans, aircon units create air flow, but they also remove heat from the air to lower the temperature of a room. 

Portable air conditioning units are significantly more expensive to buy than most fans and use much more energy. Running a portable air conditioning unit all day would cost almost 20 times as much as running a typical freestanding fan.

Because air-con units use more energy than other cooling devices, running one also results in more CO₂ emissions.

If you do need to use air conditioning, make sure you get the right size unit for the room you’ll be cooling. Check that there are no gaps where the exhaust pipe goes out of the window, as this lets warm air back into the room.

Top tip: keep internal doors closed when an aircon unit is running to stop warm air entering from other parts of the house. When you turn the unit off, unplug it at the wall to stop it using energy while in standby mode. 

Typical cost for 24 hours of continuous use: £0.07 – £0.09

Like air conditioning units, evaporative air coolers remove heat from the air to lower its temperature. Instead of using a refrigerant chemical like in an air conditioner, evaporative air coolers use a fan to move air over water. When water evaporates, it cools the air in the space near the unit.

A small, portable evaporative air cooler is likely to have a similar or slightly higher running cost compared to a typical fan. But they’re generally more expensive to buy. 

Compared to portable aircon units, evaporative air coolers use less energy and have lower CO₂ emissions.

Make sure you keep rooms well ventilated. Since these units evaporate water, they can increase the amount of moisture in the air in your home.

Top tip: keep internal doors closed while using an evaporative cooler. This will prevent warm air from entering the room and unplug when not in use.

Top up your insulation

Home insulation works in a similar way to a thermal mug or flask. The flask slows the rate that heat escapes or gets into the liquid, keeping hot drinks hot and cold drinks cold.

Insulation will help to keep your home cool in summer and warm in winter. Typical costs for wall, floor and loft or roof insulation depend on your home and the type of insulation you’re installing. 

Add solar film to your windows

Adding solar control film to your windows, will help reduce the heating effect of sunlight shining through the glass. Costs vary depending on the film you choose as well as the size and number of windows you want to cover.

If you decide not to cover all of your windows, prioritise the ones that get the most sunlight. These include south facing windows, or those in rooms that get the warmest. 

Open your windows

This sounds obvious, but you have to open the right windows at the right time. When the air is cool outside, opening windows at all sides of your house will let cool air flow through. If it’s a particularly warm day and the air is warmer outside than inside, close windows to keep the warmer air out.

Close your blinds and curtains

This is also a matter of timing. It’s usually easier to stop heat entering a home than it is to cool it down again. Close blinds and curtains when the sun is shining through a window. Only open them when the sun has moved away as this will prevent heat from the sunlight coming through the glass. 

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