Human thermal sensation and comfort in a non-uniform environment with personalized heating

Abstract

Background: Thermal comfort in traditionally uniform environment is apparent and can be improved by increasing energy expenses. To save energy, non-uniform environment implemented by personalized conditioning system attracts considerable attention, but human response in such environment is unclear.

Objectives: To investigate regional- and whole-body thermal sensation and comfort in a cool environment with personalized heating.

Methods: In total 36 subjects (17 males and 19 females) including children, adults and the elderly, were involved in our experiment. Each subject was first asked to sit on a seat in an 18°C chamber (uniform environment) for 40min and then sit on a heating seat in a 16°C chamber (non-uniform environment) for another 40min after 10min break. Subjects' regional- and whole-body thermal sensation and comfort were surveyed by questionnaire and their skin temperatures were measured by wireless sensors. We statistically analyzed subjects' thermal sensation and comfort and their skin temperatures in different age and gender groups and compared them between the uniform and non-uniform environments.

Results: Overall thermal sensation and comfort votes were respectively neutral and just comfortable in 16°C chamber with personalized heating, which were significantly higher than those in 18°C chamber without heating (p<0.01). The effect of personalized heating on improving thermal sensation and comfort was consistent in subjects of different age and gender. However, adults and the females were more sensitive to the effect of personalized heating and felt cooler and less comfort than children/elderly and the males respectively. Variations of the regional thermal sensation/comfort across human body were consistent with those of skin temperature.

Conclusions: Personalized heating significantly improved human thermal sensation and comfort in non-uniform cooler environment, probably due to the fact that it increased skin temperature. However, the link between thermal sensation/comfort and variations of skin temperature is rather complex and warrant further investigation.

Keywords: Energy saving; Heated seat; Non-uniform environment; Personalized conditioning system; Skin temperature; Thermal comfort; Thermal sensation.