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The comparison between a heat pump and gas depends on four numbers: the gas you use, the boiler efficiency, the JAZ and the ratio between the two prices. Here we hold the JAZ at the average measured by Fraunhofer ISE in existing houses, 3.4 [7], and vary the others.

The electricity price

A house using 20,000 kWh of gas in a year, a 90% boiler, gas at 11.93 ct/kWh, the 2026 BDEW average for single-family houses [9], without standing charges. The first electricity price is the 2026 BDEW average for households, 37.0 ct/kWh [8]; the other two are test values to show the effect, not observed tariffs.

With a JAZ of 3.4 the heat pump uses about 5,294 kWh in a year: each cent less on the electricity price is worth about €53 a year. The calculator shows the same figure for your data. If the heat pump has a separate meter with its own standing charge, that charge belongs in the sum alongside the price per kWh.

The boiler efficiency

The boiler efficiency determines how much heat the house actually used, and therefore how much the heat pump has to deliver. Same house, electricity at 37 ct/kWh:

A less efficient boiler means the house needs less heat than the gas suggests: the heat pump has to produce less, and the comparison is more favourable to it. If you do not know your boiler’s efficiency, you can try two values and see how much it changes.

What is left out

The comparison does not include the purchase price of the heat pump, incentives, loans, maintenance or payback time. Prices are constant throughout the year. For your case, use the calculator with your bill; what the JAZ means is explained in JAZ, SCOP and COP.