Guide · Buying
What is SCOP on a heat pump?
The one number that decides whether your bills go up or down.
SCOP (Seasonal Coefficient of Performance) is the average units of heat a heat pump delivers per unit of electricity consumed across a full heating season. A well-designed UK air source system achieves a SCOP of 3.5–4.5, meaning 1 kWh of electricity produces 3.5–4.5 kWh of heat; anything below 3.0 usually indicates flow temperatures that are too high.
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SCOP versus COP
COP is a snapshot at one operating condition, usually quoted at 7°C outdoor and 35°C flow. SCOP averages performance across a whole season, including cold days and defrost cycles. Manufacturer COP figures always look better than the SCOP you will experience.
Always compare quoted SCOP at the same flow temperature. A SCOP of 4.6 at 35°C and 3.4 at 55°C can be the same machine.
What a SCOP figure is worth in money
- SCOP 3.0 — 12,000 kWh of heat costs about £1,080 a year at 27p/kWh.
- SCOP 3.5 — about £925 a year.
- SCOP 4.0 — about £810 a year.
- SCOP 4.5 — about £720 a year.
How to get a higher SCOP
- Design for the lowest flow temperature the emitters allow.
- Upsize the worst-performing radiators rather than the whole house.
- Use weather compensation instead of fixed flow temperature.
- Avoid oversizing the unit, which causes short cycling.
- Insulate and draught-seal before the heat loss survey.
Frequently asked questions
- What is a good SCOP for a heat pump in the UK?
- 3.5 to 4.5 for a well-designed air source system. Ground source systems commonly reach 4.0–5.0 because the source temperature is more stable.
- What is the difference between COP and SCOP?
- COP is efficiency at a single test condition; SCOP is the seasonal average, which is what your bill reflects.
- Where do I find the SCOP of my quoted system?
- It appears on the MCS performance estimate your installer must provide, stated at the design flow temperature for your home.
- Energy Saving Trust — Heat pump efficiency, running cost and SCOP benchmarks (UK).
- MCS Certified — Installer certification scheme required for grant eligibility.
- Nesta — How to Heat 28 Million UK Homes — Independent research on heat pump deployment and running costs.
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