Integration of heat pumps in positive energy districts – Simulation and monitoring results from IEA HPT Annex 61
IEA HPT Annex 61 has investigated heat pump (HP) applications in positive energy districts (PED) by simulation and monitoring in order to derive recommendation for district integration of HP. HP offer unique features for load balancing and waste heat recovery which are favourable features for a high HP performance to reach ambitious objectives of PED. Based on a state-of-the-art analysis of PED definitions and realized PED, five categories of integration options have been derived from individual building to a central HP integration, which are further investigated by simulation and monitoring of 14 HP installations in PED. Presented results cover interim results from simulation and monitoring both for new built and retrofit cases. In newly built systems, special attention has to be paid to system losses and auxiliaries as well as to integration variants to preserve low temperature levels and thereby maintain high HP and system performance. As retrofit strategies, a centralised integration has the advantage of low installation expenditure on individual building level when many houses are to be connected. Centralised solutions can also exploit simultaneous generation of heating and cooling loads, if different building loads are connected by a grid increasing the performance in combined operation. However, by centralised operation, also higher grid temperatures can be caused by individual loads, which raises the importance to keep grid temperature to a minimum level. In districts with similar building types a highly reproducible model retrofit strategy can be applied, using control and shared application of on-site PV to increase the economy of the retrofitting. Results of case studies will be documented to give recommendations and best practice systems in order to contribute to a replication and multiplication of HP integration in high performance districts like PEDs.