The effects of simulated solar radiation to the head and trunk on the thermal comfort of seated subjects

Abstract

The aim of the laboratory experiment presented in this chapter was to determine the relative effects of simulated solar radiation to the head and trunk on the thermal comfort of seated persons. It was also to determine how thermal discomfort caused by radiation exposure to both head and trunk simultaneously can be predicted from a knowledge of the levels of the individual radiation components to head and trunk separately. Ten healthy male participants were exposed to simulated solar radiation levels of 200, 400 and 600 W m−2 to the head only, 400 W m−2 to the trunk only and 400 W m−2 to the head and trunk together in an order determined by two 5×5 Latin squares. The participants wore light, clothes (0.72 clo) and physiological (skin temperatures) and subjective responses were recorded in a standard protocol involving 30 min of exposure to simulated solar radiation. The results show that there is a linear relationship between radiation level to the head and thermal sensation. An increase in 200 W m−2 corresponds to an increase of 0.7 in thermal sensation scale value. Subjects were significantly (p<0.05) less sensitive to ‘head only’ radiation than to ‘trunk only’. Exposure to trunk and head together was not found to be additive.