Seasonal Coefficient of Performance (SCOP)

A weighted-average efficiency rating that reflects a heat pump's real-world performance over a full heating season.

SCOP averages a heat pump's efficiency across an entire heating season, weighting each operating point by the hours spent there. It is the figure that actually predicts your annual electricity bill. UK MCS-listed heat pumps must publish a SCOP at "Average climate, 35°C" and "Average climate, 55°C" flow temperatures.

Typical 2026 SCOP figures look like:

ASHP @ W35: 4.0-4.6 (underfloor heating)
ASHP @ W55: 2.8-3.3 (existing radiators)
GSHP @ W35: 4.7-5.2
GSHP @ W55: 3.5-4.0

Why does SCOP matter? At 24.67p/kWh electricity (Ofgem Q1 2026 cap), a SCOP of 3.5 gives heat at 7.05p/kWh — cheaper than oil and roughly on par with mains gas. A SCOP of 2.8 gives heat at 8.81p/kWh, which is borderline against gas. Always ask your installer to design to the highest SCOP your fabric and emitters allow. See our heat pump vs gas comparison.