Definition: SCOP (Seasonal Coefficient of Performance) measures a heat pump’s efficiency averaged across a whole heating season. A SCOP of 3.5 means the unit delivers 3.5 kWh of heat for every 1 kWh of electricity it uses — the higher the number, the cheaper your heating.

SCOP vs COP

COP (coefficient of performance) is a snapshot taken at a single test condition — for example 7°C outside air and 35°C flow temperature. SCOP averages performance across a standardised heating season (the EN 14825 test), including cold snaps and defrost cycles, so it is a far better predictor of real annual running costs. MCS-certified installers use SCOP-based estimates when designing your system. Our guide to COP and your heating bills covers the difference in detail, and there is a separate COP glossary entry.

What SCOP means for your bills

At the July–September 2026 price cap of 26.11p/kWh, a heat pump running at a SCOP of 3.5 delivers heat at roughly 7.5p per kWh — slightly cheaper than a 90%-efficient gas boiler at around 8.1p per kWh of useful heat (gas at 7.33p/kWh). Well-designed air source heat pumps typically achieve a SCOP between about 3.2 and 4.0; lower flow temperatures and generously sized radiators push it higher.

You will find the figure on the manufacturer’s datasheet and on your MCS installation certificate. Check the flow temperature it was measured at: the same heat pump might score a SCOP of 4.2 at 35°C but only 3.3 at 55°C, so quotes should state both the SCOP and the design flow temperature it assumes.

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