Discomfort due to air velocities in spaces.

Draught is maybe the moat common cause or complaint in ventilated or air conditioned spaces. The purpose or the present study* is to investigate experiaentally under which conditions man can be expected to experience draught. Draught is here defined as an unwanted local cooling of the human body caused by air movement . Draught can be experienced even though man feels thermally neutral for the body in general, e.g., he does not know wether he would prefer a wamer or a cooler environment. The comfort equation /2/ provides information on combinations of air temperature, air velocity, mean radiant temperature and humidity that will keep most people thermally neutral. The satisfaction of the comfort equation is a necessary but not a sufficient condition for optimal comfort . It is a further requirement that no local discomtort be experienced anywhere on the human body. To omit local discomtort, caused by air movement, it is necessary to establish separate requirements for the air velocities occurring in the occupied zone or a space. Widely varying limits for velocities are given in standards in different countries, but very few experimental draught studies have been reported in the literature. The most comprehensive earlier study vas performed by Houghten /3/ who studied ten male subjects exposed to constant local velocities at the back or the neck and at the ankles. In practice, however, the air velocity in spaces is never constant , but fluctuates in a random way around a mean value. In the present experiments a study was made of the subjective responses of a larger number of both male and female subjects exposed to fluctuating velocities with varying amplitudes and frequencies at different air temperatures.