Climate change and thermal bioclimate in cities: impacts and options for adaptation in Freiburg, Germany.

The concept of physiologically equivalent temperature (PET) has been applied to the analysis of thermal bioclimatic conditions in Freiburg, Germany, to show if days with extreme bioclimatic conditions will change and how extreme thermal conditions can be modified by changes in mean radiant temperature and wind speed. The results show that there will be an increase of days with heat stress (PET > 35 degrees C) in the order of 5% (from 9.2% for 1961-1990) and a decrease of days with cold stress (PET < 0 degrees C) from 16.4% to 3.8% per year. The conditions can be modified by measures modifying radiation and wind speed in the order of more than 10% of days per year by reducing global radiation in complex structures or urban areas.