The Extent and Implications of the Microclimatic Conditions in the Urban Environment: A Vienna Case Study

Recent challenges in the realm of urban studies concern better understanding of microclimatic conditions. Changes in urban climate affect cities at local and global scales, with consequences for human health, thermal comfort, building energy use, and anthropogenic emissions. The extent of these impacts may vary due to different morphologies and materials of the built environment. The present contribution summarizes the results of a multi-year effort concerned with the extent and implications of urban heat in Vienna, Austria. For this purpose, high-resolution weather data across six locations are obtained and analyzed. This allowed for an objective assessment of urban-level climatic circumstances across distinct low-density and high-density typologies. Subsequently, a systematic framework was developed for identification of essential properties of the built environment (geometric and material-related) that are hypothesized to influence microclimate variation. Results point to a number of related (positive and negative) correlations with microclimatic tendencies. Additionally, the impact of this location-specific weather data on building performance simulation results is evaluated. The results suggest that buildings' thermal performance is significantly influenced by location-specific microclimatic conditions with variation of mean annual heating load across locations of up to 16.1 kWhm(-2)a(-1). The use of location-independent weather data sources (e.g., standardized weather files) for building performance estimations can, thus, result in considerable errors.