Overcoming the landlord-tenant dilemma: A techno-economic assessment of collective self-consumption for European multi-family buildings

Around half of the EU population lives in multi-family buildings, in which the landlord-tenant dilemma poses a significant barrier to low-carbon retrofits. Collective self-consumption (CSC) could present a promising way to overcome this barrier by creating mutual benefits for landlords and tenants. However, the techno-economic, climatic, and regulatory conditions for CSC show large variations in European countries, which raises the question how they will impact CSC benefits. In this study four different CSC regulations are integrated into a mixed-integer linear programming model, which determines the optimal retrofitting measures in a renter-occupied multi-family building under varying energy cost, climate, and envelope efficiency levels. The results show that CSC is beneficial for both landlords and tenants in all of Europe except for buildings in Western and Central Europe with an average U-value below 1.4 W/m$^2$K and gas costs below 0.08 €/kWh. The findings also suggest that the landlord-tenant dilemma for decarbonizing heat persists in all European climates, pointing to the need for further support measures. In Southern Europe these could be provided in the form of more favorable CSC incentives for buildings with heat pumps, while in Central and Western Europe other measures, e.g. subsidies for heat pumps and renovation, are required.