Cost per hour to run air con in the UK in 2026

Straight numbers for a typical UK household at 2026 electricity prices. Everything based on the current Ofgem cap of 24p per kWh.

The headline figures

For a standard 2.5 kW single split system (the size in most UK bedrooms and small living rooms):

• Cool mode on a hot day (30 degrees outside): 18 to 24p per hour
• Cool mode on a mild day (24 degrees outside): 10 to 15p per hour
• Heat mode in autumn (12 degrees outside): 12 to 18p per hour
• Heat mode in winter (2 degrees outside): 20 to 28p per hour
• Idle (unit on, room at setpoint, compressor off): 1 to 2p per hour

Every unit runs the compressor hard at first, then eases off once the room reaches setpoint. The “per hour” figure above is an average across a full session.

By room size

Small bedroom or home office (10-14 sq metres, 2.5 kW unit) Cool mode hot day: 16-22p per hour. Heat mode autumn: 10-15p per hour. Full evening use (4 hours): 65p to £1.

Standard bedroom (15-20 sq metres, 2.5 kW unit) Cool mode hot day: 20-26p per hour. Heat mode autumn: 13-18p per hour. Full evening use: 75p to £1.20.

Living room (20-30 sq metres, 3.5 kW unit) Cool mode hot day: 24-32p per hour. Heat mode autumn: 16-22p per hour. Full evening use: 90p to £1.40.

Big open-plan lounge (30-45 sq metres, 5 kW unit) Cool mode hot day: 32-45p per hour. Heat mode autumn: 22-30p per hour. Full evening use: £1.30 to £1.90.

Monthly cost in typical use

Family home, main living room 4 hours a night, main bedroom 1 hour before sleep, June to August cooling:

• Bedroom: £8 to £12 a month
• Living room: £18 to £28 a month
• Total: £26 to £40 a month for a comfortable summer

Compare to a portable running the same pattern: £45 to £70 a month. Fitted saves £20 to £30 a month in summer alone.

Winter heating months

Same rooms, October to March, using air con for evening heating in place of turning the boiler on for one or two rooms:

• Bedroom (1 hour a night): £3 to £6 a month
• Living room (4 hours a night): £15 to £25 a month
• Total: £18 to £31 a month

Compare to running gas central heating to warm those two rooms: £120 to £180 a month for the whole house on.

Yearly saving from air con heating the two rooms in shoulder seasons: £150 to £300.

Why the numbers vary

Three factors that move the range up or down:

1. Unit efficiency. A premium unit runs at 30% less electricity for the same output. If you plan heavy use, spend more upfront.
2. Insulation. A well-insulated room stays at setpoint with the compressor mostly off. A draughty room forces the compressor to run continuously.
3. Setpoint. 22 degrees costs half what 18 degrees costs, for identical comfort. Do not over-cool.

Three habits that cut cost 40 to 60%

1. Set to 22 in summer, not 18. Every degree lower doubles the compressor load.
2. Set to 20 in winter for heating. Higher setpoints extend runtime without warming faster.
3. Turn off when the room is empty. Modern units reach setpoint in 8 to 12 minutes.

Get a real quote with running cost estimate

Every survey a Cooler Spaces installer does includes a running cost estimate for your specific setup. Fill in the quote form and three vetted installers will quote you within 24 hours.

Or check the prices page for a rough install bracket first.