The effect of exposure time on the percentage of people dissatisfied with draft was studied by exposing subjects to the airflow for 1 h. The results showed that the percentage of subjects dissatisfied with draft increased dramatically in the first 20 min of the exposure, then changed slowly in the last 40 min of the exposure. Based on the experimental results, a model was established to correlate the percentage of dissatisfied due to draft with exposure time as well as airflow velocity, temperature and turbulence intensity. The model is useful to design the air conditioning systems and the layouts of the interior spaces of buildings. (C) 2012 Elsevier B.V. All rights reserved.