Mitigation and adaptation in multifamily housing: Overheating and climate justice

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 'Gründerzeithaus' 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.