Advice
Fans, air conditioning, heat pumps, boilers and heaters compared, with clear running costs per hour and the cheap changes that make the biggest…
More and more people ask us two questions: how do I keep my home cool in a heatwave, and how do I keep it warm without dreading the bill? This guide answers both, with real running costs, so you can choose what works for your home and your budget.
All the costs below use the Ofgem price cap for 1 October to 31 December 2026: electricity at 26.3p per kWh and gas at 8.0p per kWh. Your own rates may be a little different, so check your bill. For the full side-by-side tables, see our keeping warm and cool page.
Summers are getting hotter, and many British homes were built to hold onto heat, not get rid of it. Upstairs bedrooms under the roof and flats with big south-facing windows can become uncomfortable, and for older people, babies and anyone unwell, heat can be dangerous.
At the same time, heating is still most households' biggest energy cost, and some fuels have jumped. Heating oil was about 1.20 pounds a litre in September 2026, roughly double the price earlier in the year, which hits off-gas homes around Forest Row hard.
The Centre for Sustainable Energy reported in October 2026 that more people are asking about air-to-air heat pumps for cooling. It also estimated that keeping a home at a safe temperature in summer with active cooling could add 60 to 140 pounds to a typical household's bills, and push 600,000 to 1.4 million more households into fuel poverty. So the cheap, low-tech options matter as much as the gadgets.
Think of it as three steps, from cheapest to dearest.
Most summer heat comes in through windows as sunshine. The single most useful thing you can do is close curtains or blinds on sunny windows during the day, especially on the south and west sides of the house. Light-coloured or lined curtains work best.
Shading from the outside is even better, because it stops the heat before it reaches the glass. A garden parasol, a shade sail or climbing plants in front of a sunny window can make a real difference for 20 to 60 pounds. External blinds, shutters or an awning are the gold standard, at roughly 150 to 800 pounds per window.
Turn off things that make heat: the oven, old-style light bulbs and gadgets on standby. On hot days, use the microwave or cook outside.
Open windows when it is cooler outside than inside, which is usually from the evening to early morning, then close them as the day heats up. Opening windows on opposite sides of the house, or upstairs and downstairs, creates a through-draught that flushes warm air out.
A fan does not lower the temperature of the room, but air moving over your skin can make you feel several degrees cooler. It is also by far the cheapest way to feel comfortable:
A cheap trick: put a frozen bottle of water in front of a fan for a cooler breeze.
If steps one and two are not enough, air conditioning will cool a room, but it costs the most to run.
The fitted system costs more up front but is cheaper and quieter to run, because a portable unit has to push hot air out through a hose in the window, which lets heat back in. A fitted system must be installed by someone with F-gas certification.
If you have solar panels, run fans or air conditioning in the afternoon while the panels are generating. Hot days are usually sunny days, so your cooling can cost next to nothing.
The cheapest heat is the heat you do not lose. Most of these cost little or nothing:
When you are sitting in one place, heating yourself is far cheaper than heating the room:
Compare that with a 2 kW plug-in heater, which costs about 53p an hour. Over a long evening, that is the difference between a few pence and 2 pounds or more.
To compare different heating, look at the cost of each kWh of heat that actually reaches your room. Here is roughly what it costs to warm a typical living room for an hour, which needs about 1.5 kW of heat:
Two things stand out. First, a well-installed heat pump is now as cheap to run as gas, and cheaper than oil or LPG, because it delivers three to four units of heat for every unit of electricity it uses. Second, every plug-in electric heater, whether fan, oil-filled, panel or convector, turns electricity into heat one for one. None of them is "cheaper per unit" than another, whatever the advert says. The difference is only in how quickly and where they warm you.
An air-to-air heat pump, often sold as air conditioning, is the one appliance that cools in summer and heats in winter. In winter it heats a room for about 10p an hour, cheaper than a gas boiler, and in summer it cools the same room for around 10p to 24p an hour.
They suit single rooms, flats and smaller homes well. They do not heat your hot water, and they blow warm or cool air rather than using radiators, so they are not a like-for-like swap for a whole-house heating system. Ask any installer about noise, where the outdoor unit will go, and their F-gas certification.
Every home is different. If you are not sure what suits yours, whether that is cooling a hot bedroom, choosing between a heater and a heat pump, or checking a quote, get in touch. Our advice is free and independent, and we sell nothing. You can also find heat pump and solar installers on our vetted local list, and grants on our grants page.