Exploring thermal comfort and pleasure in outdoor shaded spaces: Inspiration for improving thermal index models

Engaging in outdoor activities offers numerous benefits for physical and mental well-being, highlighting the importance of prioritizing outdoor comfort and safety. Shaded spaces are sought after during hot summers due to their lower surface temperatures and improved thermal comfort. This study conducted group walking experiments in both overhead layers and tree-shaded areas to investigate variations in thermal comfort based on different thermal environments and activity levels. The findings reveal significant differences in the thermal environment between the two areas, with tree shading reducing mean radiant temperature by approximately 3 °C and wind speed by about 1 m/s. Regardless of the walking space, the lowest thermal pleasure and comfort are experienced at a speed of 1.80 m/s. Moreover, the study demonstrates that thermal pleasure (Tp) is influenced by both the objective thermal environment and the human body's thermoregulatory mechanisms. It is also affected by subjective psychological expectations, reflecting the combined outcome of metabolic heat production, external thermal stimuli, and psychological emotions. Thus, pedestrians experienced different levels of thermal pleasure based on their walking speeds and the type of shaded space. These findings underscore the importance of integrating physiological and psychological factors into thermal index models to accurately evaluate outdoor thermal comfort conditions. The study contributes to developing improved thermal index models by enhancing their correlation with the perceived thermal sensations and considering the emotional aspect of thermal pleasure. The implications of this research can guide urban planning efforts to provide more comfortable and enjoyable outdoor shaded spaces.