Following an extension of the project until July 2019, the main evaluation period will run from July 2018 to June 2019. The measurement data will be finally evaluated in the second half of 2019 and the final results are expected to be published in early 2020. The final evaluation will cover 54 installations. The following evaluation contains interim results for the efficiency analysis of conventionally operated heat pumps (no external control via SG-Ready).
The interim evaluation covers the period October 2017 to November 2018. In doing so, 22 air source and 12 ground source heat pumps could be considered. The balance boundary for determining the SPF is shown in Figure 2. In addition to the mainly monoenergetic operation, 4 systems each with an additional oil boiler and an additional solar thermal system are being evaluated. The buildings were constructed between 1850 and 2001.
Figure 3 summarizes the bandwidths and mean values of the SPF, separated according to the heat sources outdoor air and ground. The higher SPF level of ground source heat pumps is mainly due to the higher heat source temperatures during the core heating period. In the lower part of the graph a simplified, static estimation of the CO2Eq emission savings of the heat pump systems compared to a gas condensing boiler is made. Using the 2017 emission factors and the lowest and highest measured SPF, the savings are between 17% and 53%. Projections of future emission factors show the positive contribution of the increasing penetration of renewable generation in the electricity sector. In a conservative scenario, savings in 2030 would be between 38% and 64%, while the optimistic scenario would lead to savings between 65% and 82%. This shows that despite increasingly green electricity, the efficiency of heat pumps will continue to play a significant role.
Figure 4 shows, among other things, the SPF and the maximum heating circuit flow temperatures per air source heat pump, sorted by age of building. It becomes clear that a wide range of results can be found in almost all ages of building. This shows that it is not so much the age of a building as the individual requirements that are decisive for efficiency and thus the ecological and economic result.