HEATLOSSPROHeat pump running cost vs gas
Your own bills answer this better than any national average. Enter what you used last year and what you pay, and compare the boiler with a heat pump.
In short: heat pump electricity = fuel used × boiler efficiency ÷ SCOP. A heat pump is cheaper to run while electricity costs less than SCOP ÷ boiler efficiency times the fuel price per kWh. With SCOP 3.5 and a 90% gas boiler, that is about 3.9 times.
Running cost calculator
How the comparison works
- Heat needed. The boiler turned your fuel into heat at its efficiency: 12,000 kWh of gas at 90% is 10,800 kWh of heat. The heat pump has to deliver the same.
- Electricity. A heat pump moves several units of heat for every unit of electricity. Over a season that ratio is the SCOP: 10,800 kWh ÷ 3.5 = 3,086 kWh of electricity.
- Cost. Multiply each by its price. Add the gas standing charge to the boiler side only if the heat pump lets you disconnect the gas completely.
The SCOP is the number that matters most, and it depends on the design more than on the brand. Every degree lower flow temperature raises it by roughly 2–3%. That comes from radiators sized for the room's real heat loss: see radiator output at heat pump temperatures.
Size it right first
A heat pump that is too big cycles on and off and loses efficiency; one that is too small leans on its backup heater. Both raise the running cost. Start from the heat loss: estimate it from your gas use in a minute, or calculate it room by room in the HeatLoss Pro designer in about 5 minutes. Drawing is free; a full calculation with a PDF report costs €1.
Frequently asked questions
How much does a heat pump cost to run?
Take the heat your boiler delivers in a year (fuel used × boiler efficiency), divide it by the heat pump's SCOP to get the electricity it needs, and multiply by your electricity price. A house that burns 12,000 kWh of gas a year in a 90% boiler needs about 10,800 kWh of heat; at SCOP 3.5 that is about 3,100 kWh of electricity.
Is a heat pump cheaper to run than a gas boiler?
It depends on the ratio between your electricity and gas prices and on how efficiently the heat pump runs. A heat pump is cheaper while electricity costs less than SCOP ÷ boiler efficiency times the gas price per kWh: at SCOP 3.5 and a 90% boiler, less than about 3.9 times. A heat-pump electricity tariff, a lower flow temperature or dropping the gas standing charge all tip the balance further.
What is SCOP?
The seasonal coefficient of performance: the heat a heat pump delivers over a whole heating season divided by the electricity it uses. A well-designed system with radiators or underfloor heating at 35–45 °C typically reaches 3.5–4.5. Running radiators hotter, at 55 °C, often brings it down to 2.8–3.2.
How can I lower a heat pump's running cost?
Run it at the lowest flow temperature that keeps the house warm, which may mean a few bigger radiators. Use weather compensation, so the flow temperature drops in mild weather. Size the heat pump to the real heat loss, not bigger, and choose an electricity tariff with cheaper hours for heating and hot water.
Do the whole house in 5 minutes
Trace your floor plan and see every room's heat loss, the heat pump size and the radiator check as you draw. Free to try, nothing to install, no sign-up.
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