Effects of Humidity on Thermal Comfort in Office Space : Part 2-Subjective Experiment under the Constant SET^* Conditions

Abstract

Subjective experiments were conducted in order to investigate the effect of indoor humidity on subjective thermal comfort under the constant SET^* conditions. Two levels of SET^*, SET^*26℃ and SET^*28℃, were set. Four relative humidity conditions, 35%RH, 55%RH, 65%RH and 75%RH, were examined for each SET^*, adjusting the air temperature. Subjects were exposed in a climate chamber for 180 minutes. They were asked to walk up and down 12 steps every 10-minute during the first 90 minute, 20 steps every 5-minute during next 15 minutes, and then 12 steps every 10-minute again during the last 75 minutes. Effects of indoor humidity on subjectve thermal comfort, humidity sensation were moderate under the steady state. It would be because of higher temperature at lower humidity in order SET^* to be kept at constant for 4 humidity conditions. People felt the air was warmer and reported greater discomfort at high humidity when their metaboric rate was higher. Subjective dryness sensation was lower under the transient conditions with 1.6met of metabolic rate than steady state with 1.2met. It was observed that their skin moisture was significantly higher at high humidity even under the constant SET^* conditions.