How Much Does Air Conditioning Cost to Run in the UK?

The short answer

A typical 2.5kW domestic wall-mounted air conditioning unit draws roughly 0.5kW to 0.8kW of electricity in normal cooling operation. At a UK electricity price of around 27p per kWh, that works out at approximately 14p to 22p per hour.

Crucially, an inverter system does not run flat out continuously. Once the room reaches the set temperature the compressor slows down, so average consumption over an evening is usually well below the maximum figure quoted on the unit's data plate.

Typical UK running costs by scenario

These are estimates rather than guarantees. Your actual figures depend on your tariff, the unit's efficiency rating, insulation, glazing and how low you set the thermostat.

• Bedroom unit, 6 hours overnight: roughly 60p to £1.20 per night.
• Home office, 8 hours a day: roughly £1.00 to £1.80 per day.
• Living room on a hot afternoon and evening: roughly £1.20 to £2.50 per day.
• A UK summer with around 25 genuinely hot days: often £25 to £70 for a single room.

What drives running cost most

• Set temperature — every degree lower increases consumption noticeably. 23–24°C is comfortable and far cheaper than 18°C.
• Solar gain — south and west-facing rooms with large glazing cost more to cool. Blinds and solar film reduce the load before the unit even starts.
• Unit sizing — an undersized unit runs at maximum output constantly. An oversized one short-cycles. Both waste money.
• Efficiency rating — look at SEER (cooling) and SCOP (heating). A high-SEER unit can use 20–30% less electricity than a budget model.
• Insulation and draughts — the better the room holds temperature, the less the system works.

Heating mode is usually the cheaper story

Modern air conditioning units are heat pumps. In heating mode they typically deliver 3 to 4.5 units of heat for every unit of electricity consumed. That makes them significantly cheaper to run than electric panel heaters, and competitive with gas central heating for warming a single room.

Many UK households find the heating function is the part they use most — taking the chill off a home office in October without heating the entire house.

Simple ways to cut running costs

• Close blinds or curtains on sunny elevations during the day.
• Use 24°C rather than 19°C — the comfort difference is small, the cost difference is not.
• Run the unit earlier at a moderate setting rather than blasting it once the room is already hot.
• Keep filters clean; a clogged filter increases consumption and reduces output.
• Keep doors closed so you're only cooling the space you're using.