MEASUREMENT OF RELATIVE HUMIDITY AND EVALUATION OF ITS IMPLICATION ON THERMAL COMFORT AT A TROPICAL ENVIRONMENT

Abstract

ABSRACT The attainment of a desirable combination of temperature, relative humidity and air movement for human beings in a tropical environment is studied and presented in this paper. Atmospheric influence on human’s sensation of thermal condition depends on the interaction of heat, moisture and air i.e Dry Bulb Temperature (DBT), relative humidity (RH) and air flow rate and thermal radiation with the human body. Each can have a dominating effect. In addition to a wet and dry bulb thermometer, an experimental evaporative humidifying unit constructed to aid in achieving thermal comfort was also employed. The DBT and WBT (Wet Bulb Temperature) in an isolated room were measured alongside the thermal conditions of some human beings of different sex and ages between 30 and 35 years of age (the human subjects were engaged in normal activities and wearing normal clothing) in a room of dimension 8.24m x 3.46 m x 3.89 m. Variation in their thermal comfort was noted with varying RH and air speed for the months of August, September and October 2004. Their thermal comfort range was observed to be between the RH ranges of 59 and 70 %, DBT range of 26 to 31 oC, and air flow rate of between 4.18 and 6.27 m3/s. There are no psychological and physiological differences in response to exposures of the above ranges in the room and thermal shock was not experienced by the human subjects on moving out of the room. Keywords: Dry bulb temperature, Relative humidity, air flow rate, thermal comfort.