Study on human skin temperature and thermal evaluation in step change conditions: From non-neutrality to neutrality

The purpose of this study was to explore how the human body adapts to an environment as the temperature changes, and to describe the relationship between the objective skin temperature and subjective thermal evaluation. The influence of short-term thermal experience, which based on minutes and hours scale, could be considered on the prediction of thermal sensation. Usually, the indoor temperature set point is close to neutral, in which state the heat transfer between environment and human body is at a low level. Therefore, we mainly focused on the changes from non-neutral to neutral, to observe the effects of thermal experience in neutral environment. A chamber experiment was conducted with 20 subjects and used five conditions. The control group was maintained at 26 °C. The other conditions consisted of two phases in which subjects were exposed to a hot or cold temperature for a period of time and then go into a 26 °C room, which is considered a neutral environment. We measured the skin temperature on the chest, upper arm, and lower limb. The subjects were asked to complete thermal evaluation questionnaires about thermal sensation, thermal comfort, and thermal acceptance. The skin temperature of subjects varied for the different conditions. We found that even if a poor thermal environment was improved slightly, the thermal satisfaction of subjects increased significantly. This study describes two methods for the prediction of thermal sensation, and the results contribute to our understanding of the mechanism of adaptive thermal comfort.