18 May 2017
The compulsory energy labelling for heat pumps within the European Union will have a large influence on the design of heat pump systems. In the future, most buildings will be nearly Zero Energy Buildings (nZEBs). Due to these reasons we should learn more about real operation conditions for heat pumps in nZEBs and how well these are reflected by the performance data for the labelling, in order to be able to influence a revision of the regulations if so needed.
In this study, operation parameters such as flow temperature (heating water) and brine temperature were analyzed in real operation in two different nZEBs. Factors that were studied were compressor control technology (on/off or inverter), performance of an extra storage tank for the heating system and choice of distribution system.
The results show that the flow temperature was higher than what is described in the standard harmonized with the labelling regulation (EN14825) for a low temperature application. However, the brine temperatures were often considerably higher than the test conditions described in EN14825. The conclusion is that more similar test data from heat pumps in nZEBs are needed when the regulation is to be revised five year after publication in order to secure that heat pumps optimized for the label also are optimized for real operation in a nZEB. Another finding was that in order to reach the highest overall energy performance the heat pump and the heating system must be optimized together and not separately, which often is the case today.