Heat pump seasonal coefficient of performance
of a heat pump
at the most basic level is a representation of the energy out (kw heat) compared to the energy in (kw of electricity). A COP of 4 may be given which would indicate that for every 1kw of electricity the heat pump uses to run it will output 4kw of heat to the home or hot water store.
is referring to the seasonal average
, this is a more important figure as the cop may only state the best case scenario. For instance an air source heat pump running on a mild day and outputting a low heat to a well insulated home would hit the maximum cop of say 5 or more but in the depths of winter it would only manage 2.5, the average is calculated and each appliance is rated.
SCOP and SEER are new ratings driven by the E.U ErP directive in order to make a clearer and more fair comparison for homeowners, previously when just the COP was given it was easy for heat pumps to be mis-sold. The cost difference between electricity prices and (for instance) gas prices have meant that often it is not cost effective to install a heat pump in place of a more traditional heat source but when salespeople could state the maximum efficiency rather than average it was confusing for the end user.
SEER is the seasonal energy efficiency rating in cooling which we won't go into here, many heat pumps are capable of cooling a space as well as heating. SEER this measures that efficiency and gives it a rating in the same way as the SCOP rates heating. We will be mainly focussing on heating spaces and water within this article.