Three free ways to cool your home without raising your energy bill

The energy price cap will rise by £63 in October, the third increase this year. For a typical 3-bed semi, that means an extra £5.25 a month on the direct debit, just as the last heatwave of the summer arrives. The instinct is to turn on the air conditioning or run the fan all day. But there is a simpler way.

As reported by Ideal Home, three completely free methods can keep a house cool without adding a penny to the bill. The advice is timely: the Met Office has warned that 30°C days are becoming more common in southern England, and the average UK home was built before 1970, built to trap heat, not release it.

Block the sun before it enters

The single most effective free measure is to stop solar gain before it heats the fabric of the house. Close blinds, curtains or shutters on south- and west-facing windows between 10am and 6pm. The Energy Saving Trust estimates that this can reduce indoor temperatures by up to 5°C on a hot day. Reflective blinds, the silver-backed ones, work best, but any thick curtain will do. The catch is that many homeowners open curtains for light, not realising they are turning the house into a greenhouse. The rule is simple: if the sun is on the window, block it.

Create a through-draught without a fan

Once the outside temperature drops below the indoor temperature, typically after 8pm in summer, open windows on opposite sides of the house. This creates cross-ventilation, which can move air at 1-2 metres per second without any electricity. A 2019 study by the University of Cambridge found that cross-ventilation can reduce indoor temperatures by 3-4°C compared to a sealed house. The trick is to open windows on the ground floor on one side and on the first floor on the other, using the stack effect to pull cooler air through.

But the method only works if you close the windows and blinds again by mid-morning. Leaving them open during the day lets the hot air in. The Energy Saving Trust recommends a ‘night purge’, opening everything wide at night, then sealing the house by 9am.

Use fans smartly, or not at all

A standard 50W desk fan costs roughly 2p per hour to run at current price cap rates (about 24p per kWh). That is not nothing, but it is far cheaper than a portable air conditioner, which can use 1.5 kW and cost 36p per hour. The free trick is to use the fan only when you are in the room, and to place it near an open window to draw in cooler air from outside. A bowl of ice in front of the fan creates a DIY evaporative cooler, the ice costs nothing if you have an ice tray and a freezer that is already running.

What this misses is the bigger picture. The UK’s housing stock is among the worst in Europe for overheating, according to a 2023 report by the Climate Change Committee. The free methods work for a few days, but they do not solve the long-term problem. For that, homeowners need external shading, shutters, awnings or solar-control glazing, which costs money but improves the EPC rating and reduces cooling demand permanently.

The immediate action is clear: close the curtains on the sunny side, open the windows at night, and run the fan only when you are in the room. Do it today, and the next heatwave will cost you nothing but a bit of discipline.