How much does it cost to heat a 150 m² home?
Illustrative examples · WattRumo English edition
A home of 150 m² does not have a fixed heating bill. Insulation, local climate, thermostat settings and the actual floor area heated make a substantial difference. This example illustrates the calculation method, not a forecast.
Assumed heating demand
Suppose 150 m² is heated, reference heat power is 65 W/m², the average load factor is 40%, heating runs 8 hours per day for 30 days per month, and the season lasts five months.
Reference heat output: 150 × 0.065 = 9.75 kW.
Average heat output: 9.75 × 0.40 = 3.9 kW.
Monthly useful heat: 3.9 × 8 × 30 = 936 kWh.
Illustrative energy bills
Electricity €0.20/kWh; heat pump COP 3.5; a 15 kg pellet bag €5.50; pellet energy 4.8 kWh/kg; pellet heater efficiency 85%.
| Heating option | Monthly | 5 months |
|---|---|---|
| Air-source heat pump | €53.49 | €267.43 |
| Wood pellets | €84.12 | €420.59 |
| Direct electric heating | €187.20 | €936.00 |
Rounded theoretical energy costs, not measured bills. Installation, maintenance, auxiliary electricity and heat distribution are excluded.
What changes the answer?
Heating one living room is not the same as heating every room. A single stove or indoor heat-pump unit may not provide suitable distribution for a 150 m² property. The 40% factor is an assumption, not a measured average.
Use the English WattRumo calculator to replace each assumption with your own tariffs, equipment efficiency and heating schedule.
All inputs in the free calculator are editable. The default figures are examples with prices expressed in euros.
Methodology and source notes
The model uses illustrative reference heat demand, not a certified heat-loss calculation. For heat pumps, actual seasonal efficiency differs from a fixed assumed COP. Calculations follow the shared WattRumo methodology. For background on heat-pump operation, see the Department of Energy. These sources explain equipment principles; they are not the source of our sample tariffs.
Editorial review: 31 October 2026 · WattRumo · Contact