Human comfort and perceived air quality in warm and humid environments with ceiling fans

The effects of air movement from ceiling fans on subjective thermal comfort and perceived air quality (PAQ) were examined for warm-humid environments. In a climate chamber controlled at three temperatures (26°C, 28°C and 30°C) and two relative humidity (RH 60% and 80%), sixteen subjects (8 males and 8 females) dressed in summer clothing (0.5 clo) were exposed to 7 levels of air speed ranging from 0.05m/s to 1.8m/s. The subjects were asked to rate their thermal sensation, comfort, PAQ, air movement acceptability, humidity sensation, eye-dryness during the 2-hand 15min long tests. Air movement significantly improves the subjects' thermal comfort, PAQ, and humidity sensation without causing dry-eye discomfort. Without air movement, the 80% acceptable limit established by the ASHRAE standard 55 was reached at 26. °C/60%RH, 26. °C/80%RH, and 28. °C/60%RH. With air movement, more than 80% of the subjects perceived the environments acceptable at 28. °C/80%RH, 30. °C/60%RH, and 30. °C/80%RH. The preferred air speeds for ceiling fans were in many cases higher than the limit specified in ASHRAE Standard, which is 0.8m/s when users have no control over the fan.