Prognosticated heat waves in the context of climate change require appropriate strategies to prevent harmful health effects in the population. In a model project within the public health department of the Kassel region, elderly living in areas at risk of over-heating will be identified and advised. The localization of high-risk residential areas was part of the planning process. Through mapping of demographic and microclimate data and the characteristics of the material of the residential buildings, high-risk areas that require preventive measures as a top priority were identified. The prevention of heat-related mortality and morbidity by communal health authorities requires close cooperation with other administrative bodies, especially with town planning departments. Mapping demographic and microclimate data and the characteristics of the material of the residential buildings can facilitate the planning of preventive measures.