Application and comparison of UTCI and PET in temperate climate conditions

  • Andreas Matzarakis Albert-Ludwigs-University Freiburg
  • Stefan Muthers University of Bern
  • Frank Rutz Fraunhofer-Institut für Angewandte Festkörperphysik


The assessment of the thermal bioclimate is based on the human energybalance and derived indices such as Physiologically Equivalent Temperature (PET) or UniversalThermal Climate index (UTCI). These two indices were compared over a period often year based on hourly data in a middle European city with a temperate climate. Theanalysis performed shows that the differences obtained result from the different thermophysiologicalsettings of clothing insulation. For conditions with extremely high vapourpressure values, UTCI yields higher values than PET, which could describe the thermophysiologicalstress more appropriately.