Deriving the operational procedure for the Univers

Authors: Peter Bröde Dusan Fiala Krzysztof Błażejczyk Ingvar Holmér Gerd Jendritzky Bernhard Kampmann Birger Tinz George Havenith

Publish Date: 2011/05/31

Volume: 56, Issue: 3, Pages: 481-494

PDF Link

Abstract

The Universal Thermal Climate Index UTCI aimed for a onedimensional quantity adequately reflecting the human physiological reaction to the multidimensionally defined actual outdoor thermal environment The human reaction was simulated by the UTCIFiala multinode model of human thermoregulation which was integrated with an adaptive clothing model Following the concept of an equivalent temperature UTCI for a given combination of wind speed radiation humidity and air temperature was defined as the air temperature of the reference environment which according to the model produces an equivalent dynamic physiological response Operationalising this concept involved 1 the definition of a reference environment with 50 relative humidity but vapour pressure capped at 20 hPa with calm air and radiant temperature equalling air temperature and 2 the development of a onedimensional representation of the multivariate model output at different exposure times The latter was achieved by principal component analyses showing that the linear combination of 7 parameters of thermophysiological strain core mean and facial skin temperatures sweat production skin wettedness skin blood flow shivering after 30 and 120 min exposure time accounted for twothirds of the total variation in the multidimensional dynamic physiological response The operational procedure was completed by a scale categorising UTCI equivalent temperature values in terms of thermal stress and by providing simplified routines for fast but sufficiently accurate calculation which included lookup tables of precalculated UTCI values for a grid of all relevant combinations of climate parameters and polynomial regression equations predicting UTCI over the same grid The analyses of the sensitivity of UTCI to humidity radiation and wind speed showed plausible reactions in the heat as well as in the cold and indicate that UTCI may in this regard be universally useable in the major areas of research and application in human biometeorologyThis work was supported within the COST Action 730 “Towards a Universal Thermal Climate Index UTCI for Assessing the Thermal Environment of the Human Being” The stimulating input from the lively discussions with our colleagues within this action is gratefully appreciated COST is supported by the EU RTD Framework Programme

Keywords: