Thermal Comfort Improvement between Two Urban Parks with Different Vegetation Structures

The urban heat island effect has become increasingly serious in recent years under the influence of climate change and global warming. Rising temperatures caused by the heat island effect significantly impact the quality of life in cities because it directly affects people's satisfaction with the urban environment and their use of outdoor spaces. This study used a mobile heat stress tracker to measure microclimate factors, including temperature (dry-bulb temperature), relative humidity, wind speed, and wet-bulb globe temperature (WBGT) at a distance of 1.5 m above the ground. The variance in the thermal comfort of two 2 urban parks (Taipei Botanical Garden and Zhonghe Park) was analyzed through the measured data. Research results showed that the average temperature and WBGT in the understory of the botanical garden was 2℃ lower than on the sidewalk of the street. The single-layered and low vegetation coverage of Zhonghe Park allows for better ventilation and minimal humidity difference between inside and outside of the park. However, it also results in a significant WBGT difference of up to 4.5℃ between the pavement and the understory areas, indicating that the distribution of WBGT within Zhonghe Park varies significantly. The multi-layered and high vegetation coverage of Taipei Botanical Garden intercepts solar radiation through multiple layers of vegetation. This vegetation structure helps disperse the understory's cooling effect on the park's pavement areas. The maximum WBGT difference between the pavement and understory was only 0.9℃, indicating a relatively even distribution of WBGT within Taipei Botanical Garden. Visitors walking on the pavement can experience similar thermal comfort as in the understory within the park. © 2023 Taiwan Forestry Research Institute. All rights reserved.