1 EFFECT OF SWEAT ACCUMULATION IN CLOTHING ON TRANSIENT THERMOPHYSIOLOGICAL RESPONSE OF HUMAN BODY TO THE ENVIRONMENT

The experiments involving clothed subjects are conducted to reproduce the situation in which people enter an air-conditioned room just after sweating, and analyzed using a combined model, which consists of two-node model for thermophysiological response of human body and simultaneous heat and moisture transfer model for thermal and hygric behavior of clothing. The experimental and calculated results of the skin temperatures, the clothing temperatures and the weight are compared. By tuning the parameters related to the moisture transfer in and around the clothing, a quantitative grasp of the characteristics of the moisture behavior during the process is tried in the analysis. INTRODUCTION In an environment where body temperature cannot be regulated without a lot of sweating, we often try to get rid of heat from our body by turning on the air conditioning systems or moving into a conditioned room. Just after the change of the environment, we will feel 'cool' or 'comfortable'. But the sweat accumulated in clothing evaporates gradually, until the heat loss from our body can be more than needed and at last we might feel 'cold' or 'uncomfortable'. Is this situation proper for our health? Isn't there any better way of controlling the environment? In order to clarify this problem, it is necessary to investigate, first of all, the thermophysiological response of human body to an environment taking into account moisture accumulation in clothing. In other words this problem should be treated as a non-steady state problem. A lot of studies have been made on human thermal sensation and thermal comfort, but most of them discuss only steady state and treat clothing just as a resistance to heat and moisture transport (ASHRAE, 1997). Very few studies consider the moisture capacity of clothing. Experiments in which subjects are exposed to thermal transient conditions have been conducted (Hardy et al., 1966; Takemori et al., 1995). The sweat rates and evaporation rates under heat stress have been measured (Kakitsuba et al., 1997). These studies are for unclothed subjects and there are few measurements for clothed subjects or for the temperature of clothing itself. Heat and moisture transfer between the skin and the clothing has been investigated from various viewpoints (Mochida et al., 1977; Farnworth, 1986; Lotens et al., 1995). The relation between the physiological response of human being and the non-steady characteristics of the clothing has not been fully clarified in their studies. Jones et al. (1992) have studied the non-steady state characteristics of the heat and moisture transfer between the human body and the ambient. However, in that study, the moisture transfer in and around clothing is not investigated enough in a real situation. In this study, so as to clarify the effect that moisture accumulation in clothing has on the physiological response of human body in the transient state, we conducted experiments involving clothed subjects to reproduce the situation in which people enter an airconditioned room just after sweating, and at the same time, analyzed the experimental results by making use of a combined model, which consists of two-node model for thermophysiological response of human body (Gagge et al., 1971; Jones et al., 1992) and simultaneous heat and moisture transfer model (Matsumoto, 1984) for thermal and hygric behavior of clothing. A quantitative grasp of the effects the sweat accumulation has on the human body is tried in as real a situation as possible. EXPERIMENT Procedures Table 1 Physical Data on Subjects No. Date Subject Age Weight [kg] Height [cm] 1 Sep. 2 M 22 58 178 2 Sep. 3 N 22 65.5 179.5 3 Sep. 4 H 23 65.8 174.3 4 Sep. 8 M 22 58 178 The subjects were three university students in good health. A series of experiments from No.1 to No.4 were carried out in the laboratory of Kyoto