Effect of airflow direction on human perception of draught.

Forty subjects, 20 women and 20 men, were exposed to airflows from five different directions: horizontally towards the front, the back, and the left side and vertically upwards and downwards. The subjects were exposed to stepwise increased air velocities ranging from less than 0.10 m/s to 0.40 m/s at three temperature levels 20, 23 and 26°C. The results showed that airflow direction has an impact on perceived discomfort due to draught. At 20°C and 23°C, airflow from below was perceived as most uncomfortable followed by airflows towards the back and front. At 26°C airflow from above and towards the back caused most dissatisfaction due to draught, but generally only a few of the subjects perceived discomfort at this temperature. Discomfort due to draught was most often felt at the body regions directly exposed to the airflow. These were the legs, the feet, and the lower back at airflow from below; the neck, the shoulders and the hands at airflow from above; the neck, the back, the shoulders and the legs at airflow from behind; the knee and the arm facing the windbox when exposed to air movements directed towards the side; and the hands and the knees when exposed to air movements towards the front.