COP

Coefficient of Performance

A ratio measuring how efficiently a heat pump or reverse-cycle AC converts electricity to heating.

Coefficient of Performance is the ratio of heat output to electrical input for a heat pump or reverse-cycle air conditioner. A COP of 4.0 means the unit delivers 4 kW of heat per 1 kW of electricity consumed — far more efficient than a 1:1 resistive heater. COP is typically measured at a specific outside temperature (commonly 7°C). Higher COP = lower running cost. The seasonal equivalent is ACOP (Annual Coefficient of Performance).