Cost-optimal dimensioning of combined run-around heat recovery and exhaust air heat pump systems in a Nordic hospital

Given the continuous and intense ventilation strategy and low-efficiency run-around heat recovery applied by hospital buildings to reduce risk of cross-infection, a significant amount of waste heat can hardly be recovered. They can be further recovered by utilizing well-dimensioned combination of run-around heat recovery and exhaust air heat pump (EAHP). This article analyzes the impact of implementing different sizes of run-around heat recovery, EAHP and photovoltaic (PV) system on the energy efficiency and cost-effectiveness of a demo hospital building located in Tampere, Finland. The cost-optimal sizes of these systems were investigated under two different district heating (DH) tariffs including current commercial DH price and a hydrogen waste heat DH price, which is the levelized cost of DH utilizing hydrogen production waste heat. IDA ICE 5.0 software was utilized for building energy simulations. The research indicates that 71 % of total building heating demand and 92 % of ventilation heating demand of relevant AHU can be covered by ventilation waste heat recovered by well-dimensioned EAHP and run-around heat recovery. DH tariffs show no effect on the cost-optimal sizes of investigated systems. The combination of highest-efficiency run-around heat recovery, a lowest capacity EAHP and a highest capacity PV system is recognized as the cost-optimal option under both commercial DH price and hydrogen waste heat DH price, leading to a life cycle cost (LCC) saving of 16.6 % and 12.9 % compared to the reference case with heat recovery efficiency of 46 % and no EAHP, respectively. • Cost-optimal sizing of ventilation heat recovery in hospital. • Life cycle costs analysis of hydrogen-waste-heat-based district heating. • Heat recovery covers 92 % of ventilation and 71 % of total heating demand. • Life cycle costs saving between 16.6 % to 12.9 % with optimized system.