Swiss Participation in IEA HPT Annex 62 Heat Pumps for Multi-Family Residential Buildings in Cities: Advancing Heat Pump Retrofit Strategies
The Swiss team is happy to share that they have officially joined this international collaboration project. The main objective of the Swiss project is to pool the experience gained in retrofitting heat production in existing residential multi-family buildings, mainly with monovalent and bivalent air-to-water heat pumps. The aim is to catalyze more projects by drawing up useful guidelines for the various players involved.
Carolina Fraga (SIG Geneva’s Industrial Services) is the national project leader for the contribution from Switzerland to HPT Annex 62, in collaboration with UNIGE (University of Geneva) and with the participation of CSD Ingénieurs SA. The Swiss project is in line with the Swiss Confederation’s Net-Zero 2050 strategy, supporting and encouraging the development of heat pumps in multi-family buildings, where their development must accelerate in order to achieve the energy transition targets set, notably 1.5 million heat pumps compared with 0.3 million today.
Currently (2023), Switzerland has 1.79 million residential buildings and 4.79 million dwellings. 37% of buildings are heated with oil, 17% with gas, and 21% with heat pumps. The bar chart (Figure 1) illustrates the distribution of heat pumps by building age. While heat pumps account for a large majority of heating systems in recent housing, their share decreases with the increase of the building age.
In 2023, while ¾ of units sold in the heating market are heat pumps, only 13% have a capacity above 20kW. Since the Swiss multi-family building stock requires systems above 50 kW, there is still a long way to go to its decarbonization. Even more so, because multi-family buildings represent 36% of the Swiss housing stock, with an even higher share in energy consumption because they house 60% of the Swiss population.
Therefore, the Swiss project focuses on the analysis of a concrete case study – “Montagne” – Switzerland’s largest fossil fuel / air-water heat pump substitution operation (heated area of ~28,000m2 with 250 apartments) (Figure 2). The fuel switch is achieved with the installation of 7 rooftop 75 kW A/W heat pumps and a gas boiler. The performance of this case study (a renovated building) will be compared to the performance of non-renovated buildings heated by a monovalent / bivalent heat pump (previously studied within HPT Annex 50 Heat Pumps in Multi-Family Buildings for space heating and DHW).
Furthermore, 10 factsheets of case studies of heat pumps for collective housing will be produced. They are based on detailed measurements and system analyses, under real-life conditions that were developed over the last fifteen years by the University of Geneva. They include the “lessons learned” for each case study, thus enriching the content in a pragmatic way.
It should be noted that other complementary projects are underway and offer good synergies as well as interest to Annex 62, namely: i) RENOWAVE – SP2.1: Sizing, integration, and control strategies for HP systems above 50 kW; ii) T-DROP: Lowering of heat distribution temperatures, for integration of renewables and decarbonization of multifamily buildings in dense districts.
The project team’s contribution to HPT Annex 62 is based on its specific experience of a market mainly of centralized heat production systems, and with projects involving the retrofitting of heat production systems in existing buildings. Discussions between HPT Annex 62 participants open up international perspectives that go beyond the participants’ own experience and market.
Figure 1: Residential buildings by main heating energy source and period of construction 2023
[Buildings and Dwellings Statistics 2023 – GNP Diffusion (admin.ch)]
Figure 2 : Switzerland’s largest fossil fuel / air-water heat pump substitution operation (heated area of ~28,000m2 with 250 apartments)