In temperatures between -10C and 5C heat pumps are on average more than twice as efficient as gas boilers

Coefficient of performance measurements (COP) for 550 heat pumps, by outside temperature

6 COP

A COP of 3.5 means the heat

pump supplies 3.5x as much

energy as it consumes

5

Mild cold

temperatures

4

3

Average

2

1

0.87 Gas boiler equivalent

Average outside temperature

0

−20C

−15

−10

−5

0

5

10

6 COP

Mild cold

temperatures

A COP of 3.5 means the heat

pump supplies 3.5x as much

energy as it consumes

5

4

3

Average

2

1

0.87 Gas boiler equivalent

Average outside temperature

0

−20C

−15

−10

−5

0

5

10

Guardian graphic. Source: Coming in from the cold: Heat pump efficiency at low temperatures. Joule, Duncan Gibb et al. SEAI. Note: The gas boiler efficiency rating has been converted from % to a COP rating