How the savings are calculated
A heat pump moves heat instead of generating it, delivering several kilowatt-hours of heat per kilowatt-hour of electricity. That ratio, averaged over a heating season, is the SCOP. The calculation is: electricity = heat demand ÷ SCOP, cost = electricity × price. A 12,000 kWh heat demand at SCOP 3.5 needs about 3,429 kWh of electricity — 857 € a year at 0.25 €/kWh, against 3,000 € for the same heat from direct electric heating. The percentage cut depends only on SCOP: 1 − 1/SCOP, so SCOP 3.5 cuts heating energy by 71%.
Why real SCOP varies
The label SCOP is measured per EN 14825 for a reference climate and flow temperature. Reality moves it in both directions: colder climates and undersized radiators that need 55 °C water push it down; mild coastal winters and underfloor heating at 35 °C push it up. Defrost cycles cost energy in humid weather near 0 °C, and domestic hot water at 50–60 °C runs at a lower COP than space heating. A realistic planning range for air-to-water systems in Northern Europe is 2.8–3.6; ground source typically reaches 4.0–4.6 because the ground stays warm all winter.
Typical annual heat demand
| Building | Specific demand | 120 m² example |
|---|---|---|
| New build (2010s+) | 40–70 kWh/m²·yr | 5,000–8,500 kWh |
| Renovated / insulated | 70–120 kWh/m²·yr | 8,500–14,500 kWh |
| Older, uninsulated | 120–180 kWh/m²·yr | 14,500–21,500 kWh |
Methodology
The calculator UI, the SCOP comparison table and the displayed formula all call the same calculation function. The baseline is direct electric heating at the same electricity price; installation cost, maintenance and subsidies are deliberately out of scope for v1. For what the electricity itself costs per appliance, see the Electricity Cost calculator.
- SCOP definition and label values — EN 14825 seasonal performance standard and EU energy-label (Ecodesign) documentation
- Planning SCOP defaults (air-to-air 3.8, air-to-water 3.3, ground source 4.3) — Manufacturer datasheets (e.g. Mitsubishi, Daikin, NIBE, Bosch) for average European climate — always check the label for your climate zone
- Specific heat demand ranges by building age — European building-stock typologies (e.g. the TABULA/EPISCOPE project) and national renovation guidance
Assumptions last reviewed on 27 August 2026. If a source disagrees with your battery or equipment datasheet, trust the datasheet.
Frequently asked questions
What is the difference between COP and SCOP?
COP is efficiency at a single test point (for example 7 °C outdoor / 35 °C water). SCOP averages performance over a whole heating season for a defined climate zone, per the EN 14825 standard — it is the number to plan with.
Where do I get my annual heat demand?
If you currently heat with direct electricity, your heating-season electricity use is close to it. Otherwise estimate heated area times a specific demand: roughly 40–70 kWh/m² for new builds, 70–120 for renovated and 120–180 for older uninsulated buildings per year.
How do I compare a heat pump against gas or oil heating?
Compare cost per kWh of delivered heat: fuel price per kWh divided by boiler efficiency (~0.9) versus electricity price divided by SCOP.