Study on the influence of air velocity on human thermal comfort under non-uniform thermal environment

Abstract A differentiated thermal environment with different air temperature and radiant temperature can influence human thermal comfort levels when compared to the uniform thermal environment. The environment with the difference between indoor surface temperature and air temperature is the non-uniform thermal environment. However, existing research on the non-uniform thermal environment mainly focused on the impact of radiant environment on human thermal sensation, and few studies have focused on methods to improve the thermal comfort in the non-uniform thermal environment. In order to investigate the improvement of thermal comfort due to air velocity (va) in the non-uniform thermal environment, 20 subjects were recruited, and climate chamber was used in order to create air temperature and radiant temperature differential thermal environment (Δt = 0 °C, Δt = 5 °C, Δt = 10 °C, and va = 0 m/s, va = 0.6 m/s, va = 1.2 m/s). Furthermore, questionnaire survey combined with the physiological experiments was used, and the influence of va on thermal comfort in a hot environment was discussed. The results showed that increasing va can improve thermal comfort and reduce thermal discomfort caused by the difference between radiant temperature and air temperature. When va = 1.2 m/s, the percentage of thermal dissatisfaction can be reduced by a maximum of 20% (compared to when va = 0.6 m/s). Moreover, when va increased to 1.2 m/s, the limit value of acceptable operating temperature increased by 2 °C (compared to when va = 0.6 m/s). The results of this study will be useful in providing a theoretical basis for the design of the parameters of the indoor non-uniform thermal environment.