In this paper, the effect of fabric thickness and boundary condition at lower temperature side on qmax, an objective measure of fabric warm/cool feeling is investigated through theoretical calculation and experiment. Following results are obtained. The relationship between qmax and fabric thickness is derived through mathematical model of transient heat conduction in the measurement system. The qmax value is constant above dcr, the critical thickness determined by thermo-physical properties of fabrics. This qmax can be called as intrinsic qmax value. Below dcr, qmax deviates from intrinsic qmax value to higher value in spite of the boundary condition at lower temperature side. This relationship between qmax and fabric thickness predicted theoretically is confirmed through experiment.

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We examined the total heat loss, which is the summation of heat loss and evaporation loss, for the firefighters’ protective clothing and the combined clothing samples which were prepared from the firefighters’ protective clothing, the working wear clothing and the commercial T-shirts as determined by a test method specified in ASTM F 1868 part C. We compare the total heat loss, heat loss and evaporation loss obtained from firefighters’ protective clothing and combined clothing samples with those of the commercial T-shirts and a working wear using in a fire station. We confirmed that the total heat loss of firefighters’ protective clothing and combined clothing samples were approximately 2.5 times less and approximately 2.9 times less than those of clothing materials such as T-shirts and working wear clothing, respectively. It was found that very strong correlation existed between total heat loss and evaporation loss. We suggested that the total heat loss determined according to ASTM F 1868 part C could be estimated from the values of evaporation loss.

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