Air Conditioning vs Gas Heating: Which Is Cheaper to Run?
The maths has shifted. We compare the real running costs of heat pump air conditioning against gas central heating under current UK energy prices.
The debate between gas and electric heating has been transformed by two things: the rise of heat pump technology and the change in relative energy prices. The answer is no longer straightforward, and it depends significantly on how you're comparing them.
The starting point: unit costs
Under the current UK energy price cap (July 2026), electricity costs approximately 28p per kWh and gas costs approximately 6.4p per kWh. Electricity is more than four times the price per unit. At first glance, this heavily favours gas.
Why the efficiency multiplier changes everything
A gas boiler converts roughly 90p of every £1 of gas into useful heat (90% efficiency). An air conditioning system in heat mode doesn't burn fuel at all — it moves thermal energy. With a COP of 3.5, it delivers 3.5 units of heat for every unit of electricity consumed.
- Gas boiler: 1 kWh of gas (6.4p) × 0.9 efficiency = 0.9 kWh of heat for 6.4p
- Heat pump AC: 1 kWh of electricity (28p) × 3.5 COP = 3.5 kWh of heat for 28p
- Gas effective cost per kWh of heat: 6.4 ÷ 0.9 = 7.1p
- Heat pump effective cost per kWh of heat: 28 ÷ 3.5 = 8.0p
Under current prices, gas central heating remains marginally cheaper per unit of heat — but the margin is surprisingly small, and it's closing. COP values in newer systems are reaching 4.5–5.0, which would tip the balance in favour of heat pumps even at today's prices.
Where heat pump AC wins definitively
Against direct electric heating — bar heaters, fan heaters, electric towel rails or storage heaters — heat pump air conditioning wins comprehensively. With a COP of 3.5, it produces heat at 8p per kWh compared to 28p per kWh for direct electric heating. For homes without gas central heating, this is a very significant saving.
If you currently heat a room with a plug-in electric heater or fan heater, switching to air conditioning in heat mode could reduce that room's heating cost by up to 70%.
The direction of travel
Gas prices in the UK have been volatile and are expected to remain so. Electricity is increasingly supplied by renewables, and tariffs such as Economy 7, EV tariffs and Agile pricing allow some users to purchase electricity at significantly lower rates during off-peak hours. The long-term trend strongly favours electrification of heating.