Sizing a collective heat pump system in an apartment building

impact of occupancy profiles

Abstract

Current sizing of collective heating systems utilizes conservative methods to size the capacity of the heat production unit, which results in an over sizing of the system. When collective heat pumps (CHP) are considered, an exact sizing would increase their competitiveness on the market. Residential user patterns are often not considered in the sizing strategy, neither is the simultaneity between central heating and domestic hot water (DHW) demand. This paper aims to identify the impact of occupancy patterns on sizing of a collective heat pump in an apartment building. The use of an occupancy-based heat and DHW demand model opens the possibility to reach a more appropriate sizing of the collective heat pump. This occupancy-driven model includes time dependant occupancy, temperature set points and DHW consumption. The impact of the occupancy patterns is analysed by building energy simulations (BES) in Open Studio for a case study apartment building in Belgium. A collective heat pump (CHP) system is considered where the link between consumption (building) and production (CHP) is made through a buffer tank. The production of DHW is individually supported by booster heat pumps heating up a small buffer tank. The simulation results illustrate that only 42% of the summed design capacity for heating and DHW is required to cope with the heat demand. It can be concluded that there is a significant impact of the occupancy profiles on the sizing of the collective heat pump system in this case study.