How Much Does Home Air Conditioning Cost to Run? (UK 2026)

People assume air conditioning is expensive to run. Modern A+++ inverter units are surprisingly cheap — and because they're air-to-air heat pumps, the same unit heats your home efficiently in winter too.

Roughly what it costs

Running cost depends on the unit's power, its efficiency, and your electricity price. As a rough guide, a typical 2.5kW (9,000 BTU) bedroom unit running on a normal day draws well under 1kW once it reaches temperature — often only a few pence to tens of pence per hour, not the pounds people fear. Inverter units ramp down to maintain temperature rather than blasting flat-out, which is where the savings come from.

What drives the cost

  • Efficiency rating (SEER for cooling, SCOP for heating) — A+++ units sip power; older fixed-speed units guzzle it.
  • Room size vs unit size — a correctly sized unit reaches temperature and idles; an undersized one runs flat out.
  • Insulation, glazing and sun — a south-facing glass room needs more cooling.
  • How you use it — set a sensible temperature (24–26°C cooling) rather than arctic, and use timers.

It heats too — and cheaply

The same air-con unit in heating mode is typically 300–500% efficient — cheaper per unit of heat than direct electric heating, and useful in shoulder seasons. That's why it counts as an air-to-air heat pump and now qualifies for the £2,500 grant when professionally installed. See our air-to-air grant guide.

Keep running costs down

Buy A+++ efficiency, size it correctly (sizing guide), keep filters clean, set moderate temperatures, and use eco/quiet modes overnight. Browse efficient air conditioning or get a steer from the System Finder.

Frequently asked questions

Is air conditioning expensive to run in the UK? Not with a modern A+++ inverter unit — a correctly sized room unit typically costs only pence to tens of pence per hour once at temperature.

Does air conditioning heat as well as cool? Yes — it's an air-to-air heat pump and heats at 300–500% efficiency, cheaper than direct electric heating.

What temperature is most efficient? Around 24–26°C for cooling. Every degree colder noticeably increases running cost.

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