Heat pump vs gas: what does heating cost?
At typical energy prices, running a heat pump is far cheaper than heating with gas. Here is why, how to work it out for yourself, and when the difference shrinks.
We compare the price of heat, not the price of energy
Gas is sold in cubic metres and electricity in kilowatt-hours, so their prices cannot be compared directly. A fair comparison starts from the price of usable heat, the heat the appliance actually delivers to your home.
price of 1 kWh of heat = energy price per unit ÷ heat obtained from one unit
For gas, that is the heat in the gas reduced by the boiler's efficiency. For a heat pump, it is the coefficient of performance (COP): how many kWh of heat the pump delivers from one kWh of electricity.
The result at default prices
With the calculator's default values, 1 kWh of heat costs about €0.044/kWh from a heat pump and about €0.114/kWh from gas. For a house that needs 15,000 kWh of heat a year, that comes to €667 a year with a heat pump and €1,708 with gas.
| System | Assumption | Default price | Price of 1 kWh of heat | Per year at 15,000 kWh |
|---|---|---|---|---|
| Heat pump | COP (coefficient of performance) 4.5 | €0.20/kWh | €0.044 | €667 |
| Gas | calorific value 10.5 kWh/m³ at 92% condensing boiler efficiency | €1.10/m³ | €0.114 | €1,708 |
The difference is therefore roughly €1,041 a year in favour of the heat pump.
Why a heat pump is cheaper to run
A gas boiler delivers a little less than 1 kWh of heat from 1 kWh of energy in the gas (the calculator assumes 92% efficiency). A heat pump doesn't make heat by burning anything; it moves heat from the surrounding air, water or ground and uses electricity only for the pumping. So it delivers several kWh of heat from 1 kWh of electricity. The calculator uses a COP of 4.5.
Electricity costs more per kWh than gas, but a heat pump makes up for that with a several times higher efficiency.
When the gap narrows
A heat pump's advantage is not fixed. It depends on three things:
- The ratio of energy prices. With the calculator's assumptions (COP 4.5, boiler efficiency 92%), a heat pump is cheaper as long as a kWh of electricity costs less than about 4.9 times a kWh of gas. At the default prices that ratio is around 1.9.
- The real COP. A value of 4.5 is optimistic. The seasonal coefficient (SCOP) is often lower, especially with a higher heating-water temperature and in hard frost.
- The type of heating system. A heat pump works best with a low-temperature system such as underfloor heating or larger radiators. It is less suitable for old radiators that need very hot water.
If energy prices change, recalculate the result in the calculator.
What the comparison doesn't include
The comparison covers running costs only. It leaves out the price of the equipment, installation, maintenance and any subsidies. A heat pump usually costs more to buy, so the payback period matters for the overall picture.
The numbers in the tables and examples are based on the calculator's default values (rough average prices for Slovakia). Real costs differ with your prices, equipment and house.
Frequently asked questions
Is a heat pump always cheaper than gas?
Not always. With a low real COP, a high heating-water temperature or a very unfavourable electricity-to-gas price ratio, the gap narrows. At typical prices, a heat pump is usually cheaper to run.
What COP should I assume?
The calculator uses a COP of 4.5 for all heat pumps and air conditioners. In practice, the seasonal coefficient differs with the type of pump, the water temperature and the climate, so treat the result as an estimate.
Is a heat pump worth it in a house with old radiators?
It works there too, but when the water has to be heated to a high temperature, the COP drops and the saving shrinks. Low-temperature heating gives the best results. We recommend a professional assessment before you decide.