Influence of mean radiant temperature on thermal comfort of humans in idealized urban environments

Studies about thermal comfort of humans in urban areas require the meteorological parameters air temperature, air humidity, wind speed, short- and long wave fluxes. The radiation fluxes can be expressed for this studies by the mean radiant temperature, a parameters with high variability in urban area at least by the modification of the global radiation. Wind speed in urban areas is influenced by the urban obstacles and their orientation. This two factors mean radiant temperature and wind speed can be modified or changed by different height to width ratio or orientation. Aim of the study is to quantify the influence of the height to width ratio and effect of the orientation in an a typical urban canyon in a western European City. For this purpose hourly measurements of air temperature, air humidity, wind speed and global radiation of a ten year period have been used in order to calculate the mean radiant temperature and the physiologically equivalent temperature. The simulations have been done by the use of the RayMan model, which is able to transfer the global radiation from an area with free horizon to urban structures. An idealized urban canyon has been simulated and modified in his height and width and orientation by 10° step changes. The results shows that the mean radiant temperature can be modified very strong and is important for the quantification of hat stress and possible adaptation strategies in urban areas.