Coefficient of Performance (COP)

The instantaneous ratio of heat output to electrical input for a heat pump, measured at a single operating point.

The Coefficient of Performance (COP) is the heat-pump equivalent of miles-per-gallon. A COP of 3.5 means the unit produces 3.5kW of heat for every 1kW of electricity drawn. Manufacturers quote COP at standardised test conditions, most often A7/W35 (7°C outdoor air, 35°C flow temperature) where modern units hit COPs of 4.5-5.0.

COP is a snapshot figure, so it deteriorates as outdoor temperatures fall or flow temperatures rise. Pushing the same unit to A-7/W55 (cold morning, hot radiators) might drop COP to 2.0. That is why SCOP (the seasonal average) is a better real-world metric.

For Cornish customers worried about January performance, our coastal climate is unusually mild: mean January temperature around Falmouth is 6.7°C, well above the rest of the UK. That means the COP penalty heat pumps suffer in cold snaps is much smaller here than in, say, Yorkshire. See our heat pump page for system selection advice.