Heat pump electricity use: how many kWh your house needs a year
Enter floor area and energy class, or your gas use: the calculator divides the heat demand by the measured SPF and shows the kWh of electricity a year.
Worked through by Radif Partners · Editorial policy · How we calculate
Electricity a year
4,185 kWh
€1,148 a year, €96 a month
| Heat a year | 14,229 kWh |
|---|---|
| Electricity per m² | 30 kWh |
| Electricity price | 27.44 ct/kWh |
| Cost a year | €1,148 |
| Good system (top of range) | 2,904 kWh |
| Weak system (bottom of range) | 5,473 kWh |
Step-by-step calculation
- 140 m² × class D × Bavaria climate: 14,229 kWh of heat a year, about 19 % of it hot water.
- 14,229 kWh ÷ SPF 3.4 = 4,185 kWh of electricity.
- Range measured in older homes (Fraunhofer ISE): SPF 2.6 to 4.9, so 2,904 to 5,473 kWh.
Estimate under the funding guideline and the law as of October 2026, not advice. Only the bank’s grant approval is binding. How we calculate
A heat pump’s electricity use is the heat demand of the house divided by its seasonal performance factor (SPF, Jahresarbeitszahl). The SPF tells you how many kWh of heat the system makes from one kWh of electricity over the year. The Fraunhofer ISE institute measured it in occupied existing buildings in Germany: air-to-water heat pumps averaged 3.4, ground-source units with a borehole 4.3. A 140 m² house in class D in Bavaria needs about 14,229 kWh of heat a year, based on the class midpoint and the Bavarian climate. An air-source heat pump uses 4,185 kWh of electricity for that, roughly 30 kWh per m² of floor area, and a ground-source unit 3,309 kWh. Measured air-source SPFs ranged from 2.6 to 4.9, which in the same house means 2,904 to 5,473 kWh. If you heat with gas today, enter the figure from your bill instead of area and class: 20,000 kWh of gas becomes about 4,600 kWh of heat pump electricity.
The formula behind electricity use
Electricity use equals heat demand divided by SPF: there is nothing more to it. Only the two inputs are hard. The calculator estimates heat demand from the energy class on your energy certificate (Energieausweis) under annex 10 of the Building Modernisation Act. Each class covers a band; the calculator takes its midpoint as an assumption and applies your state’s climate from the degree days of the German weather service. The SPF comes from the Fraunhofer ISE field test of heat pumps in existing buildings, measured mainly in 2024 on 49 air-to-water and 13 ground-source systems. It describes the unit itself; with buffer tank and backup heater the system figure is somewhat lower. If you are buying a house and have no energy certificate at hand, ask for the previous owner’s gas bills and enter those instead.
Electricity use by energy class
For a 140 m² house in Bavaria, using the measured average SPFs:
| Class | Heat a year | Air-source | Ground-source |
|---|---|---|---|
| B | 7,733 kWh | 2,274 kWh | 1,798 kWh |
| C | 10,826 kWh | 3,184 kWh | 2,518 kWh |
| D | 14,229 kWh | 4,185 kWh | 3,309 kWh |
| E | 17,941 kWh | 5,277 kWh | 4,172 kWh |
| F | 22,271 kWh | 6,550 kWh | 5,179 kWh |
| G | 27,839 kWh | 8,188 kWh | 6,474 kWh |
From class B to class G the electricity need more than triples. If you know the energy figure on your certificate, the small calculator below finds the class:
Your efficiency class
Class
E
| Final energy a year | 18,850 kWh |
| Air heat pump electricity | 4,801 kWh |
Reference climate, not adjusted for your state.
The spread in the measurements
The average hides how differently identical units perform. Air-to-water SPFs ranged from 2.6 to 4.9, ground source from 3.6 to 5.4. In the class D example house that is 2,904 to 5,473 kWh for the air-source unit and 2,635 to 3,952 kWh for ground source. The grant requires a design SPF of at least 3.0. Change the SPF in the calculator if your installer has worked out a figure of their own.
From kWh to euros
The calculator multiplies use by the tariff from the Federal Network Agency monitoring report: 27.44 ct per kWh with a separate meter, 31.70 ct with a shared one. For the example house with an air-source unit that is €1,148 a year. Which tariff fits is covered under heat pump tariff and heat pump electricity price. The comparison with your current heating is in the heat pump cost calculator, the legal energy classes under Building Energy Act.