Waste Heat Recovery by Electric Heat Pump from Exhausted Ventilating Air for Domestic Hot Water in Multi-Family Residential Buildings

The article discusses the possibility of recovering waste heat from the exhaust air from the ventilation system of multi-family residential buildings. A system of waste heat recovery from the extracted air with an electric heat pump was proposed for the preparation of domestic hot water (DHW). The proposed system has been analysed in TRNSYS 17 software for exemplary multi-family residential building. The influence of exhaust air humidity and heat pump outlet temperature on the energy effect was analysed. For the analysed case and the Polish conditions of electricity production, a possible reduction of the final energy amount for DHW preparation (EKW) by 35.1% and primary energy consumption (EPW) by 9.1% was determined in comparison with the use of a gas condensing boiler only. The factors influencing the energy effect of the system for the recovery of waste heat from the exhaust air were indicated. The authors specified directions of further research aimed at determining how to recover available waste heat from the exhaust air with lower energy expenditure and for which installations in the building they should be used.