The efficiency of a heat pump system can be expressed purely for the unit itself and no external power requirements (e.g. pumps) or for the wider system whole or part) at a single standard operating point. In addition the efficiency can be expressed over the season and hence a range of source and/or delivery temperatures.
The table below summarises this in principle.
When considering the wider system there are various system boundaries that can be used.
See Glossary of Terms for CoP, CoSP, SCoP and SPF.