Perception of draught in ventilated spaces

Abstract

One hundred subjects were exposed to air velocities fluctuating in the same manner as in typically ventilated spaces. Each subject, dressed to obtain a neutral thermal sensation, participated in three experiments at an air temperature of 20, 23 and 26°C. In each experiment subjects were sedentary and exposed to six mean air velocities ranging from 0·05 to 0·40m/s. They were asked whether and where they could feel air movement and whether it felt uncomfortable. Based on the results a draught chart (figure 18) has been evolved identifying the percentage of subjects dissatisfied due to draught as a function of the mean velocity and the air temperature. The turbulence of the air flow in real spaces makes people more sensitive to draught than was found in previous studies with laminar flow. A reduction of velocity limits specified in existing standards is required to diminish complaints. The head region was the most draught-sensitive part of the body for persons wearing normal indoor clothing. No significant differences were found between the draught senstivity of men and women.

Keywords:

• Draught
• Air velocity
• Air motion
• Thermal comfort
• Ventilation
• Indoor environment