Simulation Results

Download Annex 49 Report part 3 – Simulation of System integration, Design and Control for heat pumps in nZEB

 
Simulation Results of IEA HPT Annex 49
A focus of the Annex 49 contributions of the participating countries was the detailed monitoring of heat pump system monitoring in more than 15 different types of nZEB which is documented in the Report Annex 49 part 2. For many of the monitored system, though, also accompanying in depth investigations by simulations have been performed, Results are given in this report based on the integration, design or control of the heat pump.
A focus of these accompanying investigations was set on smart integration of the heat pump with other building components, in particular thermal and electric storages.
For the building Berghalde, a single family house with large PV installation investigated at the Steinbeis innovation centre energie+ (SIZ energie+), both self-consumption and grid supportive operation have been evaluated by adapted control as well as thermal and electric storage design. Electric storage can notably increase the self-consumption, but is not yet economically feasible depending on the boundary conditions. Moreover, control strategies and thermal storage have the potential to increase self-consumption. Design diagrams have been derived based on the investigations.
For 8 single family terraced houses in the HerzoBase project of the Energy campus of the Technical University Nürnberg, rule-based control has been applied for the load management of the central battery as well as central and decentralized thermal storages. Simulations confirm that grid load peaks could be reduced up to 24% in winter month. While direct use of PV electricity could be increased up to 21%, grid feed-in could be reduced by 10% and battery charging by 11%.
At the IWT at TU Graz, the storage of solar heat produced by solar thermal or solar PV in the building structure has been investigated. It was found that thermally-activated building system can offer a favourable option to reach high solar fraction both for PV and solar thermal yield.
At the Unit of Energy Efficient building at UIBK, two multi-family passive houses have been modelled in detail and validated with monitoring data of four year measurements. The validated models have been used to perform detailed investigations on desuperheater use, system configuration variants and optimization potentials of the nZE balance. Results confirm that with an extended PV-area instead of solarthermal, the nZE balance can be reached. A desuperheater use at low space heating demands of the building does not promise high performance increase in this configuration due to a reduced running time.
At the NTNU in Norway, the load management has been assessed from the grid perspective. By the control of the heat pump the CO2-balance of electricity use can be improved, but this may counteract with electricity pricing.
At the IET of OST Eastern Switzerland University of Applied Sciences Rapperswil, the design of capacity-controlled heat pumps for the application in nZEB has been investigated. It was found that a rather scarce design yield higher part load fractions at high COP values. Together with the NTNU, smart control has been tested. Results are ambiguous, since costs can be reduced, but at the same time energy use increases.
Results of the in-depth analysis of heat pump application in nZEB underlines the suitability of the heat pump as heat generator in nZEB. In particular by the on-site electricity production in nZEB and the optimised building loads which can be covered with low supply temperatures increase the heat pump performance even more than in other buildings. Furthermore, as a main electricity consumer, the heat pump unlocks the potential to increase PV self-consump-tion and energy flexibility by demand response. However, meeting ambitious nZEB targets still need optimised building operation, which has been addressed by the accomplished in-depth studies contributed to Annex 49.