The assessment of the thermal environment is one of the main issues in bioclimatic research, and more than 100 simple bioclimaticindices have thus far been developed to facilitate it. However, most of these indices have proved to be of limited applicability,and do not portray the actual impacts of thermal conditions on human beings. Indices derived from human heatbalancemodels (one- or two-node) have been found to offer a better representation of the environmental impact in questionthan do simple ones. Indeed, the new generation of multi-node models for human heat balance do allow full account to betaken of heat transfer and exchange, both within the human body and between the body surface and the surrounding airlayer. In this paper, it is essential background information regarding the newly-developed Universal Thermal Climate IndexUTCI that is presented, this in fact deriving from the Fiala multi-node model of human heatbalance. The UTCI is definedas the air temperature (Ta) of the reference condition causing the same model response as actual conditions. UTCI wasdeveloped in 2009 by virtue of international co-operation between leading experts in the areas of human thermophysiology,physiological modelling, meteorology and climatology. The necessary research for this had been conducted within theframework of a special commission of the International Society of Biometeorology (ISB) and European COST Action 730.
Krzysztof Błażejczyk [email@example.com], Institute of Geography and Spatial Organization Polish Academy of Sciences, Twarda 51/55, 00‑818 Warszawa, Poland
Gerd Jendritzky, University of Freiburg Chair of Meteorology and Climatology Werthmannstraße 10, 79085 Freiburg: Germany
Peter Bröde [firstname.lastname@example.org], Leibniz Research Centre for Working Environment and Human Factors (IfADo) Ardeystr 67, D-44139 Dortmund: Germany
Dusan Fiala, ErgonSim-Comfort Energy Efficiency Holderbuschweg 47, D-70563 Stuttgart: Germany
Agnieszka Psikuta, Empa – a Research Institute of the ETH Domain Laboratory for Physiology and Protection Lerchenfeldstrasse 5, 9014 St. Gallen: Switzerland;