Strategies for implementing sunshades and street trees for pedestrian heat avoidance in street canyons

Abstract

One of the most effective adaptation strategies for mitigating heat in urban spaces, particularly in hot climates, is shielding the human body from direct solar radiation. This study evaluates the thermal environment mitigation effects of sunshades and street trees through field measurements. Additionally, the results of the sun shading effects are discussed to develop more effective strategies for pedestrian heat control in urban areas. The measurement results indicate that the shading provided by sunshades and street trees lowered the new Standard Effective Temperature (SET*) by approximately 5 °C. A particularly noteworthy finding is that the same large effect was observed in both the morning and afternoon, as well as during the daytime. In the morning and afternoon, while the amount of direct solar radiation on horizontal surfaces, such as the ground, is relatively small, the radiation incident on vertical surfaces is significantly higher. Long horizontal sunshades, extended in the east–west direction, provide 8 to 10 h of solar shading, covering almost the entire day. In contrast, shorter horizontal sunshades in the east–west direction provide only 3 to 5 h of shading, meaning that people would need to move to different spots depending on the time of day. Street trees are particularly suitable for installation at intersections, as they offer shading effects in both the east–west and north–south directions due to their vertical height. This study highlights the significant role of sunshades and street trees in improving the thermal environment for pedestrians, particularly during peak commuting hours. By strategically positioning sunshades and trees, urban planners can enhance pedestrian comfort and reduce heat exposure, contributing to a more sustainable and livable urban environment.