Study on clothing insulation distribution between half-bodies and its effects on thermal comfort in cold environments

Clothing is important for keeping the human body warm in cold environments. In Fanger's predicted mean vote (PMV) model, clothing insulation is a single input parameter that describes the dressing status of the whole body. The objective of this study was to examine the effects of the clothing insulation distribution between half-bodies. The distribution index (DI) was defined to describe the uneven level of the clothing insulation distribution. An experiment with 20 subjects and 9 different clothing conditions was conducted in a climate chamber. Subjects were asked to be sedentary and wear specified sets of garments in a 20 °C environment. The thermal insulation values of the garment sets were measured by using a thermal manikin. The nine clothing conditions were divided into four groups. Although their thermal insulations were very close, the DI values were quite different in each group. Subjective evaluations of thermal comfort were collected, and seven-point skin temperatures were measured. To investigate this topic with a wider temperature range and greater clothing diversity, a one-year continuous field study was conducted with 18 subjects. The results indicated that the subjective thermal evaluations were different when the clothing insulation levels were close and the DI values were different. Sets of garments with a lower DI were more likely to lead to lower thermal sensation vote (TSV) and more subjects preferring a warmer environment. Clothes with an uneven DI (<0.75 or >1.25) and less clothes on the lower body (DI < 1) made people more sensitive to cold environments.