The Coefficient of Performance (CoP) is a key metric used to evaluate the efficiency of a heat pump or air conditioning system. It represents the ratio of the useful heating or cooling output a system delivers to the electrical energy it consumes. In simpler terms, it tells you how much heat a heat pump can produce for every unit of electricity it uses.
Acronym: CoP
A CoP of 3.0, for example, means the heat pump produces three times the amount of heat energy than the electrical energy it uses. A higher CoP indicates a more efficient system, translating to lower running costs and reduced carbon emissions. This is particularly relevant in the UK, where the push towards decarbonising home heating has made heat pumps a central technology in the residential retrofit and new build sectors.
In a UK residential setting, a heat pump with a good CoP is essential for maintaining comfortable indoor temperatures efficiently, especially during colder months. The CoP isn't a fixed number; it varies depending on the operating conditions, particularly the difference between the temperature of the heat source (e.g., outdoor air or ground) and the temperature required by the heating system (e.g., the flow temperature for radiators or underfloor heating).
For example, a heat pump might have a CoP of 4.0 when the outdoor air temperature is 7°C, but this could drop to 2.5 when the temperature falls to -2°C. For this reason, a heat pump's Seasonal CoP (SCoP) is often a more useful metric, as it provides an average efficiency over an entire heating season.