A Fan in Winter

Abstract

In order to determine the effect of ceiling fans on human thermal comfort under winter indoor conditions, 72 subjects (36 men and 36 women) were exposed to 21°C/40% rh for 3 hours while experiencing still air conditions (0.08 m/s) and air velocities where a ceiling fan was operating in a upward-thrust mode at 2 velocities (0.18 and 0.28 m/s). Two subjective responses, thermal sensation and thermal comfort, were recorded each half hour. The results showed that after 2 hours, which may be assumed to be the maximum period of time that an individual would sit without getting up, the subjects recorded (1) the same neutral thermal sensation when the fan was at the still air condition (0.0 8 m/s) as when it was producing an air velocity of 0.18 m/s, (2) a slightly cool thermal sensation at a velocity of 0.28 m/s and (3) no significant difference in thermal comfort between still air (0.08 m/s) and velocities up to 0.28 m/s. It was concluded that the air movement created by operating the ceiling fan under winter conditions does not contribute to nor detract from human comfort nor did it produce any response resembling wind chill. These results were considered conservative since no temperature stratification existed in the test chamber air space which would be expected in exist in a conventionally heated room space.