How much does air conditioning actually cost to run in the UK?

Updated for the Ofgem price cap, July–September 2026 · 26.11p per kWh

If you're used to thinking of "air conditioning" as an expensive luxury, the running cost of a modern heat pump system usually comes as a pleasant surprise. The reason is simple: these units don't generate heat or cold the way a kettle or an electric heater does. They move heat from one place to another, and moving heat takes far less energy than creating it.

Why heat pumps are so much cheaper to run than you'd expect

Every unit we install has an efficiency rating that tells you exactly how many units of heating or cooling you get per unit of electricity you pay for. For cooling, that's the SEER rating; for heating, it's the SCOP rating. A Haier system typically delivers somewhere around 4 to 5 times more heating or cooling energy than the electrical energy it consumes. A 3.5kW unit heating a room isn't drawing 3.5kW from the wall — it's often drawing under 1kW, because most of that heat is being extracted from the outside air rather than generated from scratch.

What it costs, hour by hour

Using the current Ofgem price cap of 26.11p per kWh, here's roughly what you're looking at for a well-sized system running in a typical room:

Heating always costs a little more per hour than cooling, because the SCOP rating is typically lower than the SEER rating — extracting heat from cold outside air in January is harder work than rejecting heat from a room in July. Even so, these figures are usually well below what you'd pay to heat the same room with a portable electric heater, which converts electricity to heat at roughly 1-to-1 rather than 4-to-1 or 5-to-1.

How this compares to gas central heating

Gas is often assumed to be the cheaper option, and per unit of energy it usually still is — but a heat pump's efficiency advantage narrows or closes that gap considerably, especially for a single room you're not already heating well with an existing radiator. If you're topping up warmth in a home office, conservatory, or loft conversion, running a heat pump for just the hours you're using that room is often cheaper overall than heating the whole house through gas central heating to keep one room comfortable.

What actually drives your real-world running cost

Room size and insulation

A well-insulated, well-sized system barely has to work to hold a set temperature. An undersized unit in a poorly insulated room runs constantly at full output, which is where high bills actually come from.

The temperature you set it to

Each degree closer to the outside temperature reduces the workload significantly. Setting cooling to 20°C on a 30°C day costs meaningfully more than setting it to 24°C.

How often you cycle it on and off

Heat pumps are generally more efficient left to hold a steady temperature than repeatedly switched fully off and on, since a large part of the energy draw happens getting back down or up to temperature from scratch.

Don't forget the 0% VAT relief

On top of the running cost savings, most residential heat pump air conditioning installations currently qualify for 0% VAT under HMRC's energy-saving materials relief, running until 31 March 2027. That's a saving on the installation cost itself, separate from what you save on your electricity bill afterwards.

Running cost questions, answered directly

How much does an air conditioner cost to run per hour in the UK?

Between 11.7p and 51.5p an hour at the current 26.11p per kWh Ofgem cap, depending on unit size and whether you're cooling or heating. A 2.5 kW bedroom unit cooling costs about 11.7p an hour. A 7.1 kW open-plan unit working hard in heating mode sits at the top end. Most households running one bedroom unit through a hot week are looking at a couple of pounds, not the double-digit figures people expect.

Is air conditioning expensive to run compared to gas central heating?

In heating mode, no. A modern inverter heat pump moves roughly three to four units of heat for every unit of electricity it draws, which is why the pence-per-hour figures above are lower than people assume. Electricity costs more per kWh than gas, but you buy far fewer kWh to get the same heat into the room.

Does leaving air conditioning on all day cost more than switching it on and off?

Usually the opposite. An inverter unit uses most of its energy pulling a room down to temperature, then throttles back to a trickle to hold it there. Switching it off and on repeatedly forces it through that expensive pull-down each time. Setting a sensible temperature and leaving it is typically cheaper.