Subjective Perception and Cooling Effect for Dynamic Ventilation with Fluctuating Air Velocity

Dynamic ventilation has proven effective in enhancing indoor thermal comfort. However, previous studies often expose participants to inconsistent thermal environments, potentially compromising the accuracy of subjective evaluations. To address this limitation, this study implemented dynamic ventilation with fluctuating air velocity in an accurately controlled environmental chamber. Objective measurements of indoor air velocity and air temperature distribution are conducted, and subjective thermal sensation votes are collected under thermally consistent environments among participants. During the experiment, all participants experience similar dynamic thermal environments. The results show that participants experience thermal comfort under dynamic ventilation. Dynamic ventilation enhances convective heat transfer between the human body and the surrounding air and stimulates cutaneous cold receptors. The pronounced cooling effect of dynamic airflow contributes to a reduction in skin temperature on the head, chest, upper arm, forearm, hand, and thigh, with a temperature drop ranging from 1.3% to 2.8%. In addition, dynamic ventilation significantly reduces draft risk, with the proportion of participants reporting a dissatisfied sensation decreasing from 10% to 0%. This study demonstrates the advantages of dynamic ventilation in improving thermal comfort and minimizing draft risk under controlled and uniform environmental conditions for all participants.