Effects of Air Temperature Step Changes on Thermal Perception and Perceived Arousal in an Actual Environment under Hot-Humid Climate Conditions

摘要

The use of air-conditioning in offices located in hot-humid regions creates differences between indoorand outdoor air temperatures. Previous studies, which focused on artificial environments, found that airtemperature step changes affect human thermal sensations and comfort. However, their effect on workers’perceived arousal has been rarely discussed. The purpose of the present study is to evaluate the effects ofair temperature step changes (both up-step and down-step) on thermal perception and perceived arousal.Thirty-seven workers from two offices in Jakarta responded to a rating scale questionnaire aboutthermal perception that covered the following sub-topics: overall and local thermal sensations, thermalcomfort, satisfaction, adjustment, and perceived arousal (i.e., alertness, freshness, and concentration)during working time. Air temperature and relative humidity around the subjects were recorded every 5minutes by a data logger, from 10:00 to 17:00. During lunch time, the subjects walked to a nearby restaurant,exposing themselves to non-shaded outdoor temperature before returning to the office.Office A workers experienced larger temperature changes than Office B workers. Indoor and outdoortemperatures of Office A were 22.9 °C and 32.1 °C, respectively, whereas, for Office B they were 24.2 °Cand 29.5 °C, respectively. Perceived arousal decreased significantly in Office A after the workers experiencedthe change in air temperature. However, no significant difference in perceived arousal was registered inOffice B, likely due to a larger gap between indoor and outdoor air temperatures in the case of Office A. Thedata of just before and after the temperature step changes were analyzed: no negative correlations werefound between changes in the overall thermal sensation and alertness (p 0.05), freshness (p 0.05), orconcentration (p 0.01). Therefore, warm sensations after the air temperature changes, associated with ahysteresis effect, should have lowered the perceived arousal. Our findings suggest that thermal perceptionand perceived arousal are altered by relatively large changes in air temperature. These changes aredetermined not only by the range of air temperature steps, but also by the air temperature experiencedpreviously. In addition, mild air temperature changes in the actual environment, combined with exercise,food intake, and direct radiation exposure, induced warmer thermal sensations than those simulated throughlaboratory experiments.