How much does it cost to run a fan for an hour?

Very little. A typical desk or pedestal fan uses 25 to 50 watts, which costs around 1p an hour at the October to December 2026 price cap rate of 26.3p per kWh. Running one all night costs about 10p.

How much does a portable air conditioner cost to run?

A portable air conditioner uses roughly 0.8 to 1.2 kW, so it costs about 21p to 32p an hour at 26.3p per kWh, or around 2 pounds for a night. A fitted split system or air-to-air heat pump does the same job for roughly half the running cost.

What is the cheapest way to heat a room?

Per unit of heat, a well-installed heat pump or a gas boiler costs about 7p to 9p per kWh, oil and LPG about 13p to 16p, and a plug-in electric heater 26.3p. For warming just yourself, an electric blanket or heated throw costs only 2p to 4p an hour.

What is the cheapest way to keep a house cool in summer?

Keep the heat out first: close curtains or blinds on sunny windows during the day and open windows when it is cooler outside, usually from evening to early morning. These cost nothing. Then use fans, which cost around 1p an hour.

Keeping warm and cool: options and running costs

Keeping cool

The golden rule: stop the heat getting in first, then move air, and only then cool the air. The first two steps are free or nearly free. Cooling the air with air conditioning works, but it costs the most to run.

Free and nearly free

Close curtains and blinds on sunny windows during the day, especially south and west facing ones. Light-coloured or lined curtains work best. Cost: free.
Open windows when it is cooler outside than in, usually from the evening to early morning, and close them when it heats up. Cost: free.
Make a through-draught by opening windows on opposite sides of the house, or upstairs and downstairs. Cost: free.
Switch off things that make heat: the oven, old-style light bulbs, and gadgets left on standby. Use a microwave or cook outside on hot days. Cost: it saves you money.
Put a frozen water bottle in front of a fan for a cheap cool breeze. Cost: pennies.
Cool yourself, not the room: a cool shower, a damp flannel on your neck or wrists, cool drinks, and light cotton bedding. Cost: free.
Sleep in the coolest room, which is often downstairs or on the shady side of the house.
Shade from outside: a garden umbrella, a shade sail or climbing plants in front of a sunny window stop heat before it reaches the glass. Cost: around 20 to 60 pounds for a parasol or sail.

Cooling appliances: what they cost to run

Option	Typical power	Running cost per hour	All night (8 hours)	Cost to buy
Desk fan	20 to 30 W	under 1p	about 5p	15 to 40 pounds
Pedestal or tower fan	40 to 60 W	about 1p to 1.5p	about 10p	25 to 80 pounds
Ceiling fan	15 to 60 W	about 1p	about 6p	100 to 300 pounds, plus an electrician to fit
Evaporative air cooler	60 to 100 W	about 2p to 2.5p	about 17p	60 to 200 pounds
Dehumidifier (makes humid heat feel better)	150 to 300 W	about 4p to 8p	about 50p	120 to 250 pounds
Portable air conditioner	0.8 to 1.2 kW	about 21p to 32p	about 2.10 pounds	250 to 600 pounds
Fitted split air conditioner / air-to-air heat pump (one room)	0.4 to 0.9 kW	about 10p to 24p	about 1.25 pounds	1,500 to 3,000 pounds fitted

Fans do not lower the temperature of the room, but moving air over your skin can make it feel several degrees cooler, for a tiny fraction of the cost of air conditioning. Evaporative coolers work best in dry heat, so they help less on humid British days.

Portable or fitted air conditioning? Portable units are cheaper to buy but work hard, because the hot air hose through a window lets heat back in. A fitted split system or air-to-air heat pump cools the same room for roughly half the running cost, runs much more quietly, and can also heat the room very cheaply in winter (see options that do both). It needs to be fitted by an installer with F-gas certification.

Got solar panels? Hot days are usually sunny days. Run fans or air conditioning in the afternoon, while your panels are generating, and the cooling can cost you next to nothing.

Bigger one-off improvements

Improvement	Rough cost	What it does
External blinds, shutters or an awning	150 to 800 pounds per window	The most effective way to keep sun out, because it stops heat before it reaches the glass. No running cost.
Solar control window film	10 to 30 pounds per square metre to fit yourself	Reflects some of the sun's heat on sunny windows. No running cost.
Loft insulation	Often a few hundred pounds, and grants may help	Keeps heat out of upstairs rooms in summer as well as in during winter.
Ceiling fan	100 to 300 pounds plus fitting	Gentle, quiet air movement for about 1p an hour.
Air-to-air heat pump	1,500 to 3,000 pounds per room fitted	Cools in summer and heats in winter, efficiently.

If you live with someone who is older, very young or unwell, hot weather can be dangerous for them. Check on them often, keep at least one room as cool as you can, and make sure they drink plenty.

Keeping warm

The golden rule for winter is the same in reverse: keep the heat in first, then heat the room you are using, as cheaply as possible.

Free and low-cost ways to stay warm

Draught-proof doors and windows with brush strips and foam seals. Cost: around 5 to 30 pounds per door or window, fitted yourself.

Block unused chimneys with a chimney balloon or draught stopper. Cost: around 20 to 40 pounds. Remove it before lighting a fire.

Close thick or lined curtains at dusk to keep the heat in, and open them on sunny days to let free warmth in. Cost: free if you have them.

Turn the thermostat down by one degree. It can cut your heating use by roughly 10 percent, and most people do not notice. Cost: free.

Only heat the rooms you use, with the valves on each radiator. Cost: free.

Lower your boiler's flow temperature (the temperature of the water sent to the radiators) to around 55 degrees on a combi boiler. The boiler runs more efficiently and your home still warms up. Cost: free. Ask us if you are not sure how.

Fit radiator reflector panels behind radiators on outside walls, and bleed radiators that are cold at the top. Cost: around 10 to 20 pounds for a roll of reflector.

Lag your hot water cylinder with a jacket if it does not have one. Cost: around 15 to 25 pounds.

Warm yourself, not the whole house, when you are sitting still: layers, a hot water bottle, an electric blanket or a heated throw (costs below).

What each kind of heating costs

To compare fairly, this table shows the cost of each kWh of heat that reaches your room, then the cost of warming a typical living room for an hour (about 1.5 kW of heat).

Heating	Cost per kWh of heat	Warming a room for an hour	Notes
Air-to-air heat pump	about 6.6p	about 10p	Assumes it delivers 4 units of heat per unit of electricity.
Air source heat pump (radiators)	about 6.6p to 8.8p	about 10p to 13p	3 to 4 units of heat per unit of electricity. A good install does better.
Gas boiler	about 8.9p	about 13p	Assumes a modern boiler that is 90 percent efficient.
Wood in a stove (bought logs)	roughly 10p to 15p	about 15p to 22p	Much less if you have your own wood. Burn only dry, seasoned logs.
Oil boiler	about 13p	about 20p	Based on about 1.20 pounds a litre (September 2026), which is double last year's price.
LPG boiler	about 13p to 16p	about 20p to 23p	Based on about 85p to 1 pound a litre. Check your own supplier's price.
Plug-in electric heater (fan, oil-filled, panel, convector)	26.3p	about 39p	All plug-in electric heaters turn electricity into heat one for one, so none is "cheaper per unit" than another.
Storage heaters	depends on your off-peak rate	varies	Only good value if your night rate is low. Many Economy 7 rates are now high, so check your bill.

Small electric heaters: cost per hour

Appliance	Typical power	Running cost per hour
Heated clothing (USB gilet or socks)	5 to 10 W	under 1p
Electric blanket	60 to 100 W	about 2p to 2.5p
Heated throw	100 to 160 W	about 3p to 4p
Hot water bottle (boiling a kettle to fill it)	about 0.1 kWh per fill	about 3p a fill
Infrared panel	350 to 800 W	about 9p to 21p
Halogen heater	1.2 kW	about 32p
Oil-filled radiator on full	1.5 to 2 kW	about 39p to 53p
Fan heater on full	2 to 3 kW	about 53p to 79p

The quick win: if you are sitting in one place, an electric blanket or heated throw at 2p to 4p an hour keeps you warm for a tiny fraction of the cost of heating the room. A plug-in heater for the whole evening can easily cost 2 pounds or more.

Options that do both

Air-to-air heat pumps (often sold as air conditioning) heat in winter for about 10p an hour per room and cool in summer. They suit rooms or smaller homes, and they do not heat your hot water.

Insulation and draught-proofing keep heat in during winter and out during summer. Loft insulation helps most with hot bedrooms.

Good curtains, blinds and shutters trap warmth on winter nights and block sun on summer days.

Solar panels make free electricity on sunny days, just when you might want cooling, and help with running costs all year. See our solar guide.

Find an installer, or ask us

Our vetted local installers cover heat pumps, solar and batteries. Choose the Cooling & Air Conditioning filter to see the seven that fit air-to-air heat pumps and air conditioning, and ask any installer to show their F-gas certification. For grants towards heat pumps and insulation, see our grants page. And if you are not sure what suits your home, ask us: our advice is free and independent, and we sell nothing.

Comfortable all year, without big bills