Experimental study of thermal sensation and physiological response during step changes in non-uniform indoor environment

To examine thermal comfort and the corresponding physiological responses in non-uniform and dynamic indoor thermal environments, this article presents the investigation of thermal sensations and skin temperatures during step changes between the ambient environment and the workstation where local ventilation devices supplied air motion around the subjects’ heads. Twenty-three lab tests with human subjects were conducted to provide summer cooling in a controlled-environment chamber. Overall thermal sensations and skin temperatures were collected and analyzed. Data collected as subjects stepped between the ambient environment and the controlled-environment workstation displayed hysteresis and overshooting. That facial skin temperature correlates with thermal sensation provides a causal explanation of the overshooting and hysteresis. Further, the minimum change on facial skin temperature required to register a just-noticeable difference on thermal sensation was calculated to explore the correlation between facial skin temperature and overall thermal senation. In conclusion, thermal sensation data provide a sound quantifiable foundation for comfort-positive non-uniform indoor thermal environments. Facial skin temperature explains thermal sensation's changing characteristics during step changes in non-uniform thermal environments under varying local cooling methods.