A research group led by the German Fraunhofer Isee has carried out what it describes as the first empirical study on PV-supported two-phase HP systems in existing multi-family buildings. The findings show that substantial export of PV electricity results in a greater avoided non-renewable primary energy consumption.
An international research team conducted the first empirical study on the afterwards of PV-supported two-stage heat pump (HP) systems in existing multi-family buildings.
The research is part of the EU funded by the EU To happen Project, which aims to develop solutions that integrate both centralized and decentralized HPs. In these solutions, the centralized system heats the water, which is then heated in a second heat pump in each home.
“The selected Case Study sites are located in Spain, Italy and Austria, each of which works under different climate conditions and with different building characteristics and heating temperature requirements,” the team explained. “This diversity ensures an extensive assessment for the integration of these systems.”
The scientists in particular compared the energy performance of the proposed systems with standard solutions in existing multi-family buildings, aimed at primary energy consumption (People) and CO2 equivalent emissions by the analysis of field measuring data.
The Spanish Case Study (Case_es) is located in Pasaia, in the Basque autonomous community of North Spain; The Italian Case Study (Case_it) in Verzuolo, in the northern region of Piedmont; and the Austrian Case Study (Case_at) in Liezen, in the federal state of Styria.
According to the climate climate climate of Köppen-geiger, these locations are classified as a moderate oceanic climate (CFB), a moist subtropical climate (CFA) and a hot-summerly pure continental climate (DFB), respectively. The diploma days are 925 for Pasaia, 1,717 for Verzuolo and 2,523 for Liezen.
The building in the Spanish store was built in 2008 and has never been renovated. In Italy it was built in the 16th century and renovated between 2006 and 2008. The building with several families in Austria was built between 1940 and 1945 and renovated in recent decades. In all three cases, only two floors are counted as habitable.
The Austrian store has a heated area of 980 m², the Italian has 400 m² and the Spaniards has 620 m². The Austrian building has 18 homes and 31 inhabitants, while the Italian has 10 houses and 14 residents. The Spanish has 8 homes and 24 residents.
In Case_es, two centralized air-water use heat pumps (AWHPs) propane (R-290) as a coolant, which results in a total heating capacity of 36 kW. They are connected to a Thermal Energy Storage (TES) system, consisting of a water tank of 2,000 liters, which preheats water to a low temperature distribution tank. Each home is equipped with a decentralized propane water-water heat pump (WWHP), which offers a total heating capacity of 48 kW. The electricity used by the HPS is partly supplied by PV panels with a peak power of 15 kW.
Case_it consists of three centralized AWHPs with coolant R-32 and a total heating capacity of 45 kW. These AWHPs are linked to two TEs of a total of 1,300 liters. The total thermal capacity of the decentralized WAHPs is 39 kW for heating and 33 kW for cooling. In addition, a PV system with a peak output of 10 kW was installed on the roof, in addition to a battery system with a capacity of 22 kWh.
In Case_at, four centralized AWHPs offer a total heating capacity of 124 kW with a backup electric heating of 6 kW using coolant R-410A. They are connected to four TEs, a total of 3,200 liters and 18 decentralized WWHPs, one for each home. The decentralized HPS coolant R-32 to offer a total heating capacity of 132 kW. A PV system of 28 kW feeds the HP that is installed on the roof of the building.
The assessment period for the study was 12 consecutive months. It took from November 2023 to October 2024, for Case_es and from August 2023 to July 2024 for both Case_it and Case_at.
“The total seasonal performance factors of the heat pump systems are comparable, on average approximately 2.0 in all three case studies. Between 63.5% and 76.3% of the primary energy used for heating and cooling comes from renewable energy sources,” the scientists said. “In comparison with earlier heating supply systems, the emission of heat pump systems emissions are reduced by 65.4% to 84.3%, which achieves the target of the European Union of 60% reduction by 2030. Between 60.9% to 86.4% of the two -style pumping system are attributed to the installation of the two -stalking systems. Up to 39.1% of the photoving-oriented photoving-oriented photoving self-development of the Photoving-Angsters of the Photovolta.
They concluded that afterwards of photovoltaic two-stage heat pump systems in existing multi-family buildings is technically feasible about different climate and energy demand conditions.
The experiments were presented in the newspaper “Energy performance of photovoltaic two-stage heat pump systems in existing multi-family buildings: three case studies from Europe“Published in Energy. Researchers from the German Fraunhofer Institute for Solar Energy Systems (ISE), Spain Tecnalia Research and Innovation, Tecnzenith of Italy and the AEE of Austria – Institute for Sustainable Technologies have contributed to the research.
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