The characteristics of dynamic and non-uniform thermal radiation experienced by pedestrians in a street canyon

Thermal comfort of outdoor pedestrians is a crucial factor affecting the quality of urban life. The quantification of the thermal radiation environment near the ground of an urban street canyon is essential for understanding the thermal comfort of pedestrians. Most studies on the thermal comfort of outdoor pedestrians did not consider the dynamic changes in the thermal radiation on the pedestrian route. The mean radiant temperature for a given location does not adequately represent the effect of non-uniform thermal radiation on the human body. In this study, a simulation method is proposed to investigate thermal radiation experienced by pedestrians in street canyons. We obtained the main parameters affecting the dynamic and non-uniform thermal radiation in the central district of Guangzhou. The results show that an exponential function describes the relationship between the time a pedestrian remains in the post-change environment and the solar elevation angle (hs) as the pedestrian travels through sunlight and shadow areas. A quadratic function describes the relationship between a change in the temperature of thermal radiation and the hs and between the sunlight-shadow frequency and hs. Non-uniform thermal radiation is attributed to the direct shortwave radiation (SWdir) in sunlight areas. The different directions of SWdir irradiating the human body cause a temperature difference in the non-uniform thermal radiation between different parts of the human body.