Herbstforum Altbau 2025: Jörg Knapp – Wärmepumpen-Effizienz in der praktischen Anwendung

Jörg Knapp, a graduate engineer (FH) and head of the technical department at the Baden-Württemberg Association for Sanitary, Heating, and Air Conditioning Technology, emphasized in his presentation at the 27th Autumn Forum for Existing Buildings that in 90 percent of heat pump problems, the issue is not the unit itself, but rather inadequate planning. To avoid such problems, hydraulic balancing is crucial – this also applies to other heating systems. The lower and upper bivalent points and the heating limit temperature also have a significant impact on the efficiency of the heat pump. The expert also explained the importance of cycle times. Excessively long cycle times are detrimental to the lifespan and efficient operation of a heat pump. Values ​​between 1,000 and 2,000 cycles per year are recommended – however, up to 16,000 cycles have been measured in recent projects. Knapp also stressed the importance of the installation location, as it has a significant influence on efficiency. If the outdoor unit of an air-to-water heat pump is located in a niche, for example, the cold air cannot escape. As a result, the unit has no fresh air available as a heat source, only the already cooled exhaust air from the heat pump. This leads to increased energy consumption. Finally, Knapp also addressed the important coordination of interfaces between the electrical and heating trades and the benefits of home energy management systems (HEMS). Further information about the event and the speakers' presentations can be found here: www.zukunftaltbau.de/herbstforum