Building materials for cities and climate change - A material catalogue with recommendations

Abstract

High urban density with heat accumulating materials and sealed surfaces can cause heat stress and reduced nocturnal cooling in summer. Appropriate building materials may contribute to the mitigation of this effect. The research project evaluates building materials for façades and outer surfaces (ground) on the resulting urban microclimate and on factors like glare, acoustics and embedded energy. The present publication focuses on the impact on the microclimate. The analysis comprises the simulation of forty-seven data sets in a microclimatic model with ENVI-met. The results show that during daytime the PET for the whole neighborhood ranges between 30.1 and 36.4 °C. Choosing a bright instead of a dark color can lower the PET between 0.2 and 1.0 K. Dark colored metal sheets may cause turbulences which lead to a reduction of the PET between 2.0 and 3.8 K (compared to a bright metal sheet). However, this effect may not be reproducible under varying boundary conditions. During night-time, the resulting span of ambient temperatures between the materials reaches 21.4 to 22.0 °C (level 1.7 m). The temperature difference between the materials at the level of 10.7 m (for night ventilation) is found to be approx. 0.3 K and can be considered irrelevant.