Thermal sensation responses in hot, humid climates: Effects of humidity

Experimental data from five previous comfort studies are used to derive formulas for the thermal sensation of sedentary and near-sedentary residents, and to examine the effect of one variable, humidity, on the perceived levels of comfort. Studies in Thailand, Singapore and Indonesia (two studies) investigated indoor comfort, and a further study in Japan investigated outdoor comfort. Thermal sensations of human subjects were recorded under different conditions of temperature, air speed and humidity. In the outdoor study in Japan, solar radiation and surrounding surfaces temperature were also measured. All these studies found that the effect of humidity, expressed as the humidity ratio (gr/kg) on the thermal sensations of sedentary and near-sedentary resident persons tested, was very small to negligible, suggesting an insensitivity of the (acclimatized) subjects to the humidity level within the range encountered in the countries where the studies were conducted.