Thermal Comfort Disturbed by Local Airflows in Winter

Abstract

The human body is enveloped in a natural convection that is created by the body′s own metabolic heat. This natural convection does not cover the body′s surface equally, however, so disturbances caused by outside airflows are also not equal over the body surface. In this study, horizontal local airflows of various temperatures and velocities were directed at two locations on the bodies of several subjects: the backs of the necks and the left sides of the ankles. In this paper, the subjects′ perceptions of temperature and air motion at both locations were compared during experiments held in winter. Airflows directed at the ankles were perceived to be higher in temperature and velocity than identical airflows directed at the back of the necks, while airflows directed at the neck produced greater thermal comfort than identical airflows directed at the ankles. Therefore, the percentage of dissatisfied (PD) was smaller at the neck than at the ankles. In practical terms, to prevent the sensation of being cold, low-temperature airflows directed at the ankles should be avoided, and to increase comfort at the neck, high-temperature, high-velocity airflows should be avoided.