Performance analysis of a mini exhaust air heat pump integrated into a low energy detached house: experimental on-site performance

This paper presents the on-site performance of a mini exhaust air heat pump integrated into a low energy detached house situated in Belgium. The system consists of five components: a simple exhaust ventilation system, an exhaust air heat pump, a backup electrical resistance for space heating only, a domestic hot water storage tank and fan-coil units to heat the building. In that system, the heat source of the heat pump is the air from the ventilation system and the heat pump heating capacity is limited to 1500 W. During the night, the exhaust air heat pump produces the sanitary hot water, which is stored in a water tank. Consequently, the totality of the domestic hot water is produced by the heat pump. During the day, the heat pump can also be used to heat the building. Nevertheless, only a part of the energy requirements related to heating are covered by the machine, due to the limited heating capacity. The remaining heating requirements are covered by the backup electrical resistance. For this reason, this machine is particularly suitable for apartment buildings characterized by a low heating demand and a significant energy demand related to domestic hot water production. In the first part of the paper, the characteristics of the building case study and the different components of the system are presented. The second part of the paper describes the sensors placed in the building used to measure the on-site performance of the machine. In the third part of the paper, the on-site performance of the machine is presented. The influence of the main variables (exhaust water temperature, supply air temperature, outside temperature) on the performance is also discussed. In the last part of the paper, the performance of the whole system is estimated for a typical meteorological year. The estimation is based on the Energetic Performance of Building certificate of the building, and on empirical relationships established with the on-site performance of the machine.