Prediction of mean skin temperature as an index of human response to the thermal environment

In this paper, the steady state thermal conditions of body exercising in a hot environment is evaluated, in which the thermal equilibrium of human body seems to be attained in less than one hour. An assumption, that the regulatory thermal sweating rate is a linear function of the deviation of mean skin temperature from that of thermal neutrality, is tested and proved to be acceptable. Applying this assumption to the heat balance equation of the human body, the mean skin temperature is expressed explicitly as a function of four environmental factors (air temperature, air velocity, humidity and radiation) plus two human factors (clothing insulation, and metabolic rate). In cool environment, however, it takes more than several hours to reach thermal equilibrium, that requires the time dependent evaluation of thermal conditions of subjects who stay in a room whose temperature is lower than that of thermal neutrality. In this paper, the mean skin temperature of subjects in a non-steady state who transfer from a room of thermal neutrality to one of lower temperature is also estimated.