Mitigation and adaptation in multifamily housing: overheating and climate justice

Abstract

Can thermal retrofit measures also enhance summer heat resilience and climate justice? Two common building types of multifamily dwellings in Central Europe are investigated: the ‘Grunderzeithaus’ and post-war large-panel construction along with their different inhabitant demographics. Thermal simulations and demographic surveys were undertaken for dwellings in both building types to evaluate the effectiveness of retrofit measures in reducing winter heat demand and to understand the impacts on summer overheating. Results indicate that standard retrofitting measures can reduce the overheating risks. The high summer temperatures on the top floor can be significantly lowered to values comparable with the ground floor. The remaining overheating in highly exposed rooms is reduced by additional selective adaptation measures. Adaptation requires more than technical interventions. Demographic surveys conducted for both building types show that different social groups are affected. The economics of retrofit requires policy clarity to avoid placing additional burdens on economically disadvantaged people. Inhabitants’ active involvement in night-time ventilation are vital for avoiding overheating. Appropriate affordances and a clear guidance for manual window opening/closing can reduce overheating. However, inhabitants who are unable to act (e.g. the elderly, immobile or those with chronic diseases) will be increasingly vulnerable and disadvantaged by increased exposure to overheating. Practice relevance The existing approaches for reducing heating demand and their impacts on overheating are examined for two common building types in Central Europe: the Grunderzeithaus and post-war large-panel multifamily housing. The evidence of physical effects and social interdependencies provides a basis both for decision-makers to select suitable measures, and for inhabitants to apply appropriate behavioural practices. Thermal retrofitting strategies for reducing winter heating demand can lead to enhanced resilience to hot summer weather, but also entail inhabitants’ active involvement. Additional technical measures are needed to ensure reduced levels of overheating. Inhabitants’ practices have a significant influence on resilience and the reduction of overheating. Therefore, technical interventions must be accompanied by clear strategies to empower inhabitants to control internal temperatures using natural ventilation. Elderly or ill inhabitants may not be able to perform these practices and, therefore, remain vulnerable. Increased rents caused by retrofits may displace socially disadvantaged inhabitants.