An individual feels comfortable when metabolic heat is dissipated at the rate at which it is produced. Extensive experimentation has shown that for an average, sedentary, lightly clothed person this occurs most readily when the air in a standard room has a temperature of 24.5°C, a relative humidity of 40%, and an air velocity of 0.25m/sec. According to thermal comfort standards currently valid, 80% of all adults dressed for winter indoor conditions find temperatures acceptable between 20-23.5°C, a relative humidity of 30-60% and the air velocity at 0.15-0.25m/sec. Acceptable summer indoor temperature is between 20-26.5°C. Very lightly clothed people prefer a temperature between 26-29°C. The summer temperature can be increased to 28.5°C if the air velocity is increased to 0.8m/sec.

Moreover, two people will often choose a difference approach for deriving comfort from a given situation. For example, for a tourist from Northern Europe, comfort on a tropical island might mean a day of basking, minimally clad in the sun on a beach, whereas for a native it would more likely mean resting, fully dressed, in the shade of a tree. The tourist enjoys the very high rate of water transport through the skin without the wet feeling that a similar perspiration rate would produce in clothed state in still air at home.

Air movement enhances heat transfer between air and the human body and accelerates cooling of the human body. Exposure to wind has the same effect as lowering the temperature of still air. Thus, both processes cause the same sensation.

Air Movement then is essential for bodily comfort as it helps the body to dissipate heat gained from all sources by increasing the effects of convection and evaporation. Air movement in an occupied space gives a feeling of freshness by lowering the skin temperature, and the more varied the air currents in velocity and direction the better the effect. With room air temperatures between 18°C and 21°C, a comfortable but stimulating environment is created by a range of air movement velocities of 0.15 to 0.4m/s. A draught is created when the temperature of the moving air is too low and/or the velocity too high. Desk fans do no change the temperature of the air, but by providing a flow of air across exposed skin, especially the face, a feeling of freshness is created.