Utilizing a heat pump in a run-around heat recovery system

In Finland, 32 % of the total energy consumption results from buildings, making it necessary to decrease carbon emissions from buildings\cite{SuomenRakennusinsinoorienLiittoRILry2019}. The thermal losses through air infiltration and through the building envelope are greatly decreased, in new buildings, hence the ventilation heat losses are one of the greatest sources of heat losses from a building. The built environment is in the key position in reducing greenhouse gas emissions by improving energy expedition and thus focus on the problem of global warming. The main objective of this study was to analyse the monetary and energy savings potential of utilization of a heat pump in a run-around heat recovery system (RAHRS). The research examined two different heat pump connection types, Between and Inline connection, with different brine flow rates in the case building located in Vantaa. Cost-saving potential and difference between the heat pump combined with a run-around system and basic run-around system were evaluated. Also, the optimum sizing of the heat pump was considered. Retrofitting a heat pump into a run around system with Between connection or with Inline connection was found to be energy efficient and increase the annual temperature efficiency. There are multiple advantages as for the retrofitting of a heat pump to a system set-up such as the easiness of installation. Other advantages include a small temperature difference between the source and load temperatures over most of the operations hours and a constant source temperature which induce an efficient heat pump performance. Current building stock contains several different systems that are built according to old frameworks and regulations. This introduces new possibilities to retrofit heat recovery systems to increase the energy performance of buildings. In the case building observed in this study, the increase of annual efficiency of heat recovery in ventilation could be increased over 30 %, giving the system coverage of 90 %