Influence of domestic hot water demand profiles on energy performance of combined solar thermal and heat pump systems

A well designed and controlled application of combined solar thermal and heat pump (SHP) system in the residential sector can contribute to the objectives regarding energy performance of buildings and the use of renewable energy sources aimed at in the European EPBD and RESD directives. The share of energy demand for the production and distribution of domestic hot water (DHW) in the total amount of energy demand in residential applications is growing with the efforts to reduce the energy use for space heating (SH). Two SHP systems sized to cover SH and DHW demand of a single family, low‐energy house in Belgian climate are subjected to various DHW draw‐off profiles and setpoint temperatures of the DHW storage tank. System 1 uses a stratified tank for heat storage for SH and DHW distribution with a ground source heat pump and glazed solar thermal collectors whereas system 2 uses two different tanks in parallel for DHW and SH with an air source heat pump and evacuated tube solar collectors. The systems perform best for a DHW tank cut in temperature of 45°C to deliver the DHW profile taken from IEA‐SHC task 44/annex 38. The results indicate that lower SPF values can be expected for properly sized SHP systems when subjected to another DHW profile as a result of a change in household size.status: publishe