Commissioning and numerical performance assessment of a hybrid heat pump system for an office building

With the increased number of new measures approved each year, the European Union (EU) is aspiring towards a myriad of actions for lowering greenhouse gas emissions and increasing the share of renewable energy sources. The space heating and domestic hot water energy demand of buildings dominates the total energy use in the EU with a share of more than 20%. Moreover, the majority of the buildings are constructed before the introduction of energy saving policies. To refurbish these buildings large investments are necessary. Besides, sudden penetration of electrically driven heat pumps can endanger the entire electrical system supply network. In other to mitigate these issues, hybrid heat pump systems are proposed. In this work, the commissioning of a hybrid heat pump system for an office building is analysed through numerical simulations made in the modelling language Modelica and software tool Dymola. The installation considers two gas-fired boilers and two air source heat pumps with the total designed capacity of 500kW. By using real time measurements from the building information management, a replica of the newly installed hybrid heat pump system is modelled and performance improvement suggestions have been made in this work. Increasing the flow rate and supply temperature of the heated medium out of the heat pumps while also changing the bivalent working point of the heat pumps from 5°C to 0°C and reconsidering the control strategy can lead to the yearly natural gas use reduction of 63%, total cost savings of 18% and CO2 emission reduction of 61%