Heat pump running cost: the calculation for your climate
A heat pump does not use the same in Nice as in Strasbourg. The calculation starts from the degree-days measured by Météo-France in your département.
A heat pump’s consumption is worked out in two steps. First, the heat the house needs over the year, which depends on its area, its insulation and the climate, measured in heating degree-days (DJU): the day-by-day sum of the gap between 18 °C and the average outdoor temperature. Second, the heat pump’s yearly efficiency, or SCOP: the kWh of heat produced per kWh of electricity used. ADEME measured, on real installations, an average efficiency of 2.9 for air-to-water, ranging from 1.8 to 4.5 depending on fitting and settings, and 4.1 for ground-source. For an averagely insulated 100 m² house in the Rhône (2,058 HDD), about 13,583 kWh of heat is needed, which is 4,684 kWh of electricity for air-to-water: €930 a year at the regulated tariff. These are estimates; your current consumption, entered in the calculator, replaces them.
How much would a heat pump use in my home?
Electricity per year
4,684 kWh
| Cost at the regulated tariff | €930 |
| Heat delivered | 13,583 kWh |
| Climate (St-Genis-Laval) | 2,058 DJU |
Estimate. SCOP used 2.9 (ADEME measurements); need estimated with the site’s insulation coefficient. Space heating only, no hot water.
Checked by Radif Partners · Editorial policy · Method and sources
Consumption and cost, département by département
| Département | HDD | Heat needed | Air-to-water electricity | Air-to-water cost | Ground-source cost |
|---|---|---|---|---|---|
| Alpes-Maritimes (06) | 1,370 | 9,042 kWh | 3,118 kWh | €619 | €438 |
| Bouches-du-Rhône (13) | 1,370 | 9,042 kWh | 3,118 kWh | €619 | €438 |
| Gironde (33) | 1,491 | 9,841 kWh | 3,393 kWh | €674 | €476 |
| Rhône (69) | 2,058 | 13,583 kWh | 4,684 kWh | €930 | €658 |
| Paris (75) | 1,835 | 12,111 kWh | 4,176 kWh | €829 | €586 |
| Nord (59) | 2,359 | 15,569 kWh | 5,369 kWh | €1,066 | €754 |
| Bas-Rhin (67) | 2,267 | 14,962 kWh | 5,159 kWh | €1,024 | €724 |
| Doubs (25) | 2,408 | 15,893 kWh | 5,480 kWh | €1,088 | €769 |
All 96 départements are in the table on the heat pump by département page. Each département’s degree-days are those of the Météo-France station nearest its main town; in the calculator you can pick another station, in the mountains for example.
How much would a heat pump use in my home?
Electricity per year
4,684 kWh
| Cost at the regulated tariff | €930 |
| Heat delivered | 13,583 kWh |
| Climate (St-Genis-Laval) | 2,058 DJU |
Estimate. SCOP used 2.9 (ADEME measurements); need estimated with the site’s insulation coefficient. Space heating only, no hot water.
Real efficiency, not the data-sheet figure
Manufacturers quote a coefficient of performance (COP) measured in a laboratory at an outdoor temperature of 7 °C, often above 4. Real yearly efficiency is lower: it includes cold days, defrosting, hot radiator water and stoppages. That is why the site starts from ADEME’s measurements in occupied houses. If your installer gives you a SCOP, you can enter it under “Refine”; the calculator recomputes the consumption.
What lowers consumption
Low water temperature: the hotter the radiator water, the harder the heat pump works. Underfloor heating and oversized radiators are the best emitters. A well-set weather compensation curve, which adapts water temperature to outdoor temperature. Correct sizing (see heat pump sizing). And of course insulation: going from an average to a well insulated house cuts the heating need by about a third in the site’s calculation.
Compare with your current bill
Consumption alone does not tell you whether a heat pump is worthwhile: it must be compared with what you pay today for gas, oil or electricity. That is the job of the calculator and of the heat pump or gas boiler and payback pages.