The velocity of the air influences the efficiency of heat exchange between the air and its surroundings. This means that the heat balance for a person in a room is influenced by the speed of the air. At low air velocity, <=0.1 m/s, the effect of air movement in the room is negligible. At low air speed, the updraught of air from the body’s heat emanation will dominate the air velocity. Increased air velocity may cause dissatisfaction with the thermal climate due to cooling of parts of the body. This type of drought problem is one of the more common causes of dissatisfaction with the thermal climate.
The problem of draughts mainly affects people in sedentary jobs, who may be affected by cooling of parts of the body for extended periods of time. Not only air velocity, but also turbulence intensity disturbs the perception of comfort.