The so-called annual performance factor gauges the efficiency of a heat pump heating system. The annual performance factor is the ratio of thermal energy supplied by the heat pump system to the amount of electricity required to operate the system for one year.
Thus, it is not meant to be a snapshot of the heat pump’s operating status unde standard conditions (see coefficient of performance (COP)); instead it is influenced by several different factors.
These include, on the one hand, the heat source and heating system itself.
In the case of the heating system, the temperature difference between the heat flow and the heat return flow is of particular importance. On the other hand, the actual system operation also plays a crucial roll. Here, the flow temperature resulting from the set heating curve is the decisive factor. The term “performance factor” is also often used to refer to the annual performance factor.