Assessment of human biometeorological conditions in urban areas embedded in complex topographies in Southwest Germany

The complex region of Stuttgart, located in the south-westerly part of Germany, favours warm and humid climate accompanied by a low wind speed. Stuttgart lies in a Keuper sink and is surrounded by hills, a fact, which enforces the specific formation of these thermal and air quality conditions. The Urban Heat Island (UHI) of Stuttgart and its spatial distribution should be assessed using human-biometeorological methods. The most important and popular indices, Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI), are applied and compared. The spatial variability of the thermal bioclimate in Stuttgart is mainly governed by differences mostly in wind speed. UTCI and PET show the largest differences in the very low and high ranges due to different scaling to thermal perception and clothing models. But also in the range of thermal response, they might differ by one range in the thermo-physiological assessment scale.