Effect of outdoor thermal environment on pedestrians' behavior selecting a shaded area in a humid subtropical region

• Effect of microclimate on pedestrians' behavior was examined in a subtropical region.
• Thermal index UTCI was derived from measured parameters in sunlit and shaded areas.
• The average UTCI in the sunlit area was 8.7 °C higher than that in the shade.
• Males and females tended to wear hats and parasols, respectively, to avoid heat.
• 50% of pedestrians chose the shade when stopping at traffic signals at 40 °C in UTCI.

This study analyzes the effect of microclimatic conditions on pedestrians' behavior in selecting shaded places when standing at the traffic signals in a subtropical region of Nagoya, Japan. On-site microclimatic measurements and unobtrusive observations were performed 18 times in two periods, July to October, 2012, and May to August, 2013, in order to obtain physical data and the number of pedestrians in sunlit and shaded areas. The universal thermal climate index (UTCI) model was adopted for assessing the outdoor thermal environment in the sunlit and shaded places in this study. The average UTCI values in the sunlit and shade areas over the measured periods were 38.0 °C and 29.3 °C, respectively, and the difference was 8.7 °C. The number of pedestrians was hardly influenced by heat environment since the observations were conducted on weekdays, thus, almost all had to go out for their routine tasks or work regardless of the conditions. Male and female pedestrians tended to wear hats and parasols, respectively, in order to avoid excessive heat during the hot season. The analytical results indicate that half of the pedestrians select shaded areas when stopping at the traffic signals in a hot environment over 40 °C in UTCI. Female pedestrians are more careful to protect themselves from solar radiation including ultraviolet rays than males. “Shade Design in the City” will be a critical strategy to improve the safety, comfort, and attraction of cities in a hot environment.