Differential Coefficient of Equal Warm Sensation Line

Abstract

With a purpose to investigate the relationship between average skin temperature and wettedness of man that feels an equal thermal sensation, the experiments were conducted on sitting-resting subjects in a test chamber. The subjects were dressed in athletic short and were exposed to warm conditions for one hour.From the analysis of the present experimental data, the following conclusions were drawn regarding an equal thermal sensation. When subjects voted the thermal sensation “warm”, the average skin temperature and the skin wettedness hold different values depending upon the different combinations of ambient air temperature and environmental humidity. In other words, as the humidity gets higher, the average skin temperature goes down and the skin wettedness becomes larger. Further the data suggest that both experimentally and theoretically the locus of equal thermal sensation may not be a straight line, but rather a curved line plotted on a psychrometric chart.