Dynamic thermal responses and showering thermal comfort under different conditions

Abstract

This study conducted a series of human subject experiments on shower thermal comfort to investigate the dynamic thermal responses under different conditions. Questionnaires (including thermal sensation votes, thermal comfort votes, sweating sensation votes, and mood-related votes) and physiological parameters (including skin temperature, core temperature, heart rate, blood pressure, and brain waves) were collected from 27 subjects. The results showed that the subjects’ comfort-related votes changed dynamically during the pre-, mid-, and post-showering phases. The changes in thermal sensation, thermal comfort, fatigue relieving, and sweating sensation during the 10-min shower were 0.7 ± 0.8, 0.9 ± 1.2, 0.9 ± 1.0, and 0.9 ± 0.9, respectively. After a 10-min shower, 16 mood-related questions were answered toward positively. The heart rate and mean skin temperature of the subjects increased by approximately 10% and 8%, respectively. The body temperature tended to be more uniform, with smaller temperature differences between the trunk and extremities. The changes in core temperature, blood pressure, and brain waves were less significant because the reference test condition (25 °C air temperature, 40 °C showering water temperature, and 10-min duration) was not intensive. Further analyses indicated showering water temperature and duration were the most significant factors affecting the mid-showering thermal comfort. The ambient temperature and airspeed were the most significant factors affecting post-showering thermal comfort. The initial thermal status primarily affects thermal comfort before showering. No significant difference was observed between the elder and the younger subjects under moderate conditions.