State of the Art

Download Annex 49 Report part 1 – State-of-the-Art of heat pump application in nZEB

The political framework with the respective EU Directives and different approaches to support a harmonised definition for the implementation of nZEB in the EU member countries states is discussed: Based on a 10-year transition period for nZEB implementation for all new buildings, the nZEB requirement will become the standard by Jan 1, 2021 in the EU. Due to a rather vague definition of an nZEB in the EPBD, different harmonisation initiatives published a definition of nZEB with the intention to harmonise the implementation of nZEB in the EU member states. The Europaen Federation of Heating, Ventilation and Air conditioning Associations (REHVA) and the European stanardisation organisation CEN published a definition and system boundaries for an nZEB rating. A similar definition has been published in the USA by the DOE. CEN additionally supported the nZEB implementation with an nZEB rating procedure and a set of standard for the energy calculations, which are currently also transferred to International Standardisation Organisation (ISO) level. The EU has made amendments of guidelines regarding cost-optimality and published benchmarks as orientation of the expected ambition level.

However, the implementation of the participating countries Austria, Germany, Norway, Sweden and Switzerland, which is analysed and described in more detail, confirms, that the implementation in the single participating countries differs in terms of system boundaries, criteria and limits for the nZEB rating, which is also backed-up by other comparative studies. Thereby, the ambition level to achieve a high energy performance in the new built sector is hard to compare, which is additionally hindered due to different calculation methods and different boundary conditions used in the single countries. Therefore, a methodology to compare the ambition level across different countries has been developed using building and system simulation and tested for the countries Germany, Austria and Switzerland for a single family house. The method transforms a standard single family house to the national nZEB according to the national implementation and then back to common boundary conditions. Compared to a reference building, a methodology allows a relative comparison among nZEB implementations, which show significant difference among the countries. While some countries make a step forward to higher energy efficiency and are actually approaching a nearly zero energy consumption, other countries stay virtually on the same level as before. However, the methodology has only been tested for single family buildings and heat pump heating systems. Based on the strong differences in the results, the method should be further developed to cover other building use and shall be tested for different heating systems in order to enable a more general evaluation.

Furthermore archetype concepts for nZEB are described, and upcoming technologies used in nZEB are linked to the Annex 49 contributions. As outlook, an overview of high performance building labels is given. As general conclusion heat pumps are already well establish in nZEB building concepts and are seen as a key technologies for nZEB. On the other hand, the introduction of nZEB will promote heat pump markets also for the application in larger buildings in order to reach ambitious energy requirements. Moreover, integration of storage and adapted controls can notably improve self-consumption and grid-supportive operation. However, larger storage design for higher energy flexibility is mostly not economic for the owner at current market conditions. These results are confirmed by the investigation of Annex 49 contributions and described in detailed in the other parts of the Annex 49 reports on field monitoring, prototype developments and accompanying simulation studies.