Using a mathematical model of human temperature regulation to evaluate the impact of protective clothing on wearer thermal balance

Thermal factors are often important in determining whether a given clothing ensemble is suitable for use under specified conditions. Although final approval of a particular ensemble often involves field trials, the need for such trials can be minimized by measuring the thermal properties of the garment using a heated manikin and then predicting human behavior using a mathematical human thermal model. While many laboratories are capable of measuring the properties of garments using manikins and several mathematical models exist, there have been very few published comparisons of actual human behavior with model predictions. The purpose of this paper is to present such a comparison for soldiers wearing a Slovene Armed Forces summer clothing ensemble during a three-hour hike across a 160 m high ridge. Values measured during the trial were: oxygen consumption; skin and core temperatures; regional thermal fluxes; clothing temperature; and environmental conditions. Subjective assessments of thermal comfort were made at regular intervals during the hike. Agreement between predicted and actual behavior was reasonable, although there were significant differences which could be attributed both to deficiencies in the model and to difficulties inherent in conducting field trials of this kind.