Windsor Conference 2016 - Making Comfort Relevant - Proceedings

The Universal Thermal Climate Index UTCI assesses the outdoor thermal environment based on the multi-node UTCI-Fiala-model of thermoregulation, which was coupled with a clothing model considering the clothing behaviour of an urban population. The applicability of UTCI to exercising, resting or occupational settings is currently limited by the assumed moderate activity level (2.3 MET) and the maximum exposure time of two hours. However, the high level of detail devoted to the modelling of the physiological and clothing system will allow for expanding UTCI to varying exposure times and activity levels, as will be demonstrated by this paper. We calculated UTCI adjustment terms for activity varying from a resting to a high (5 MET) level and for exposure duration covering an 8-hour shift length in 30-min steps. Simulations with the UTCI-Fiala model were performed using the adaptive UTCI-clothing model with air temperatures from -50°C to +50°C for UTCI reference climatic conditions. The adjustment terms indicated that thermal stress decreased with shorter exposure and increased with longer times, and that high activity increased heat stress, whereas low activity increased cold stress. Effect size was moderated by stress category with greater effects of activity and exposure time in the cold compared to moderate or warm climates. These results demonstrate UTCI's capabilities for a comprehensive assessment of dynamic thermal stress in occupational and other relevant outdoor settings. However, extensive simulations are still necessary to include the effects of special leisure and work clothes.