Non-uniform distribution of clothing insulation as a behavioral adaptation strategy and its effect on predicted thermal sensation in hot and humid environments

Abstract

Adjusting clothing insulation plays a pivotal role as human behavioral adaptation to the thermal environment. Most widely used thermal comfort models, such as the PMV model, assume that the entire body is uniformly covered by clothing. Using these models in hot and humid environments, where people often wear partially covered clothing, can cause an error in predicting the thermal sensation. The object of the present paper is to investigate the effect of the assumption of whole-body uniform clothing coverage on the error of standard thermal comfort models in hot and humid environments. Investigations were performed using a three-node thermal comfort model in the temperature range of 26C to 31C at 50% and 70% relative humidity for three different clothing levels (0.4, 0.6, and 0.8 clo). The results showed that for typical summer clothing (0.6 clo and 80% body surface coverage), ignoring the non-uniformity of clothing insulation distribution can lead to an average of 0.2-to-0.45-unit scale deviation in thermal sensation depending on ambient temperature. This effect is more evident at higher ambient temperatures and humidity. Eventually, a new model was proposed for application in hot and humid environments by considering the non-uniformity of clothing coverage. The model’s performance was evaluated against multiple sets of reported experimental data.