Local Thermal Comfort and Physiological Responses in Uniform Environments

The thermal perception of different body parts can vary greatly throughout the human body and have different influences on overall thermal sensation and comfort. Various personal comfort systems (PCS) have been developed to stimulate local body parts for the purpose of enhancing human thermal comfort, yet the most effective body parts for intervention remain undetermined. Therefore, a series of climate chamber experiments under five uniform environments with three sets of suits were conducted in this study. The results showed that the head, chest, belly, and hands tended to feel no cooler than overall in cooler environments, but arms and legs felt generally no warmer than overall in warmer environments. The head, trunk and upper arms were more likely to be the comfort-dominant body parts. Additionally, the upper arms and upper back expected temperature regulation measures the most under non-neutral environments, thus they seem to be the two most needed and effective targeted body parts that a PCS could be applied to. The skin temperature and thermal sensation of limbs were more sensitive to indoor air temperatures than those of the torso. However, variations in the skin temperature of the head, chest, upper back, and calves had the strongest correlation with overall sensation vote changes. The above results and conclusions can not only serve as the basis for the future studies of local thermal comfort, but also provide theoretical guidance for the design of future PCS products.