Auswahl von Oberflächenmaterialien für Dächer und Böden zukunftsfähiger Städte

Selection of surface materials for roofs and outer surfaces (ground) in sustainable cities

A lack of shade, high urban density with heat accumulating materials and sealed surfaces lead to heat stress and reduced nocturnal cooling in summer. Suitable building materials can help mitigate these effects. To investigate this, a simulation study was conducted to test the influence of different roof coverings, materials for outer surfaces (ground) and green infrastructure (GI) on the microclimate. The analysis comprises the simulation of 38 data sets for roofs, ground materials and GI in dry and moist conditions in a microclimatic model using ENVI-met. The results for the whole neighborhood show that choosing light-colored ground materials reduces the dry bulb temperature (DBT) at the same height by up to 0.4 K and has a positive effect on the urban microclimate. However, reflective surfaces can have a negative effect on the thermal comfort of the pedestrians as the physiological equivalent temperature (PET) is 1.0 K higher above bright surfaces. This is due to reflected short-wave radiation, which significantly increases the perceived heat stress despite lower air temperatures. During daytime without shade the PET is up to 2.6 K higher at a height of 1.7 m above ground with a dry GI compared to a moist GI.