Dynamic thermal comfort of pedestrians in outdoor built environments under solar exposure: Portable microclimate control via umbrella shading

Intense solar radiation heat exposure during summer in low- and mid-latitude cities poses a major challenge to the thermal performance and usability of outdoor built environments. Umbrella shading represents a portable and behaviourally adaptive microclimate control strategy for mitigating outdoor heat exposure, yet its quantitative effects and underlying mechanisms remain insufficiently understood. This study conducted dynamic field walking experiments on a university campus to evaluate the impact of umbrella shading on pedestrian thermal comfort and physiological responses under varying solar radiation conditions. Results showed that umbrella use markedly alleviated heat discomfort, reducing mean thermal sensation vote ( TSV ) by 0.39 in males and 0.26 in females. Under high-temperature conditions, umbrellas reduced TSV peaks by approximately 1.5 units, with mean skin temperature peaks about 0.6 °C lower than without umbrellas, while tympanic temperature differences remained negligible within 12 min of exposure. The effect was mainly attributed to reduced solar radiation on the head and shoulders, lowering mean radiant temperature by 5–10 °C. A first-order stepwise regression model was developed to predict TSV from UTCI and exposure duration. The findings provide empirical evidence for the thermoregulatory benefits of portable shading and underscore the necessity of incorporating time-dependent effects in outdoor thermal comfort evaluation. This research informs climate-adaptive, low-energy design strategies to promote pedestrian travel in low- and mid-latitude cities urban environments.