Running costs
What does air conditioning cost to run?
Less than most people expect. Put your own room, hours and electricity rate into the calculator below and see the cost for a summer, or a winter, because every unit we fit heats too.
Running costs
Work it out for your home
Less than most people expect. An inverter unit works hardest for the first 15–30 minutes while it brings the room to temperature, then drops to a fraction of that to hold it. In winter it heats for less per kWh than a gas boiler. Figures below use about 26p per kWh electricity and 8p per kWh gas (Ofgem price cap, autumn 2026).
Running it for a summer
≈ £45
6 hours a day, 60 days a year
Leaving it on at a steady setpoint is usually cheaper than switching it off and blasting it back on.
As a guide, at about 26p per kWh: a single 3.5 kW split costs around 26p an hour while it pulls the room down, then 8–13p an hour to hold it, roughly £45 across a summer of six hours a day for sixty days. A 2-way multi split is about 40p an hour flat out and 13–20p holding, near enough £65 a summer, and a 3-way about 60p and 20–30p, near enough £100. In heating mode the same units put three to four times more heat into the room than the electricity they draw.
6.5–8.7p
per kWh of heat into the room. 1 kWh of electricity makes about 3–4 kWh of heat
8.7p
per kWh of heat at 92% efficiency (8p gas)
11.4p
per kWh of heat at 70% efficiency, typical for a boiler over 15 years old
Based on a 3.5 kW Haier single split drawing about 1 kW flat out and 0.3–0.5 kW once the room is at temperature, with 5 kW and 7 kW multi-split outdoor units scaled the same way, at about 26p per kWh. Leaving the unit on at a steady setpoint is usually cheaper than switching it off and blasting it back on. Your actual cost depends on your tariff, the room and how you use it.
How much does air conditioning cost to run?
At about 26p per kWh, a single 3.5 kW unit costs around 26p an hour for the first 15–30 minutes while it brings the room to temperature, then 8–13p an hour to hold it. A 2-way split on a 5 kW outdoor unit is roughly 40p an hour flat out and 13–20p holding; a 3-way on a 7 kW outdoor unit roughly 60p and 20–30p. Over a summer of six hours a day for sixty days that is about £45, £65 and £100. Leaving it on at a steady setpoint is usually cheaper than switching it off and blasting it back on.
Is air conditioning cheaper than a boiler for heating?
For one room, usually yes. A split system in heating mode delivers three to four kilowatts of heat for every kilowatt of electricity it uses, which works out at about 6.6 to 8.8p per kWh of heat against about 8.7p from a new A-rated gas boiler and 11.4p from an old one. For heating a whole house through radiators, a gas boiler is still normally cheaper, which is why Balmy fits both.
How much does it cost to run air conditioning overnight in a bedroom?
Once the room is at temperature a 2.6 kW bedroom unit ticks along at around 0.2 to 0.4 kW, roughly 6 to 10p an hour at today’s rates, so eight hours overnight is about 50p to 80p. Set it to 22 or 23°C rather than 18, use the sleep mode, and it will be at the bottom of that range. Our running-cost calculator on the air conditioning page lets you put in your own tariff.
Is air conditioning worth it in the UK?
In the right room, yes. In some houses, no. It earns its keep in a bedroom you can’t sleep in during a heatwave, a home office you sit in all day, a south-facing living room or a loft conversion that bakes. Because every unit we fit heats as well as cools, it is also the cheapest way to warm that one room in spring and autumn without running the whole house. Where it is harder to justify is a small, shaded room you use for an hour in the evening. If that is your house we will say so. We would rather you spent the money on something you will use.
Ready when you are
Price your air con in two minutes
Room size, where the outdoor unit goes, how sunny it is, and a fixed price on screen, VAT included.