Drafts in cold environments: The significance of air temperature and direction

Abstract

This paper concerns the influence of air temperature and of the direction of drafts on subjective and physiological responses. In three experimental series 58 healthy persons (50 men, 8 women, 20-29 yrs) were exposed to drafts in overall 446 experimental sessions. Drafts were applied either horizontally or vertically with mean air velocities of 0.1 to 0.3 m/s and a turbulence intensity of 50%. Air temperature was varied between 11 and 23°C and metabolic rates between <70 and 156 W/m2. These parameters were kept constant during the single one-hour sessions. The subjects were dressed for thermal neutrality. Draft-induced annoyance was registered every 5 minutes using a list of prescribed body parts and skin temperature was measured at the forearm and at the neck. Subjective and physiological responses were systematically related to air temperature. Draft-induced general annoyance, draft-induced local annoyance (neck, forearm) and the drop of the corresponding skin temperature were inversely related to air temperature. Concerning the direction horizontal drafts seem to cause somewhat stronger reactions. The predictive model developed by Toftum underestimates the percentage of persons annoyed. A modified version increases the predictive power significantly.