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Coefficient of performance (COP)

A heat pump moves heat from cold outdoor air or ground into the house. It uses electrical work to do so, but delivers much more heat than the electricity it uses. The ratio of delivered heat to work used is called the coefficient of performance, COP.

COP_{HP} = \frac{Q_H}{W}

COP of a heat pump

Q_H = Q_C + W

energy balance

Symbols

$Q_H$	heat delivered to the house	J
$Q_C$	heat taken from the cold side	J
$W$	electrical work	J

Example

The heat pump uses 2 kWh of electricity and takes 6 kWh from the air:

$Q_H = 8$ kWh and $COP = 8/2 = 4$ .

COP drops when it is cold outside, because the temperature difference becomes larger.

Practise heat pumps and refrigeration for free →

← Throttling and isentropic processes · Refrigeration COP →

Part of Thermodynamics: Heat pumps and refrigeration.