Overview

Mid-latitude cities are situated in general climatic situations making heat stress a frequent phenomenon during the warm seasons while heating of building is required during the cold seasons. Thus, many buildings in mid-latitude cities are today equipped with air-conditioning systems consuming huge amounts of energy. Urban regions modify regional climates, in particular by the formation of urban heat islands, such that heat-stress hazards are increased while energy demands for heating of buildings are reduced, as compared to their rural neighbourhoods. Global climate projections for the next decades indicate that the above- mentioned tendencies will be further increased by changing climates. However, down-scaling of global climate projections to urban scales is still an unsolved scientific problem. Nevertheless, air conditioning of buildings will, most probably, become even more common, resulting in increased energy demands for cooling of buildings, which will then cause an increase in green-house gas emissions.

Research Unit 1736 "UCaHS" addressed the complex scientific questions related to heat stress in mid-latitude cities by a multi- and interdisciplinary approach involving climatologists, urban geographers and hydrologists, physicians, architects, physicists and engineers, urban planners and social scientists. The causal chains spanning from climate modifications by urban regions to out- and indoor heat stress hazards were analysed in detail for the example of Berlin. Heat-stress risks were studied by available observational data, in particular for specifically vulnerable groups of senior people or patients residing in hospitals.