Reviews and summarises the effects of air temperature, humidity, and air movement on thermal comfort under hot and humid conditions with a view toward energy conservation. Recently, ASHRAE published a new comfort envelope in Standard 55-1992. In that standard, the upper limit of relative humidity (RH) was set at 60%. In hot and humid regions, humidity levels higher than 60% may often be observed. This upper limit of humidity is discussed based on the subjective data. In addition, the results show that under hot and humid conditions, air movement may be one of the least expensive methods of providing thermal comfort. The effect of air movement is also described.

KEYWORDS: air temperature, relative humidity, humidity, air movement, thermal comfort, air conditioning, ventilation, tropics, subtropics, energy conservation, experiment, clothing, draughts, climate chambers, evaporation, heat loss, human body, skin