Presentation No 947 – Monovalent and Hybrid Air-source Heat Pump Concepts for Existing Multifamily Buildings – Energy Performance and CO₂ Savings – 14th IEA Heat Pump Conference, Chicago, USA
Heat pump suppliers only propose hydronic concepts for buildings up to 15 kWth, and very few suggest diagrams for large air-source heat pumps (> 50 kWth) in existing multifamily building. This paper analyses the energy and environmental performance of hybrid diagrams adapted to existing and large multifamily buildings via a validated numerical simulation model. The concepts correspond to different fuel-switch scenarios with the possibility of using existing boilers as a back-up. For each concept, sensitivity analysis assesses the impact of different levels of heat demand and heat pump capacity. As a result, over the different scenarios, the seasonal performance of the heat pump varies between 2.8 and 3.3, and the overall performance (heat pump and boiler) between 1.5 and 2.9. Considering the hourly CO2eq content of the Swiss electricity mix, emissions of hybrid systems are 1.4 to 2.2 times higher than with a monovalent system. However, they remain 2.3 to 3.5 times lower than a gas boiler, which points out their adequacy as a transitional solution to proceed to a fuel-switch before retrofitting the building envelope.