Evaluation of thermal comfort in transportation micro-environments under different vegetation configurations

As an important part of road system, green plants play a significant role in improving road thermal comfort. Different vegetation configurations can effectively promote road air circulation, thus significantly improving the comfort of transportation micro-environments. In this paper, ENVI-met simulation software was used to establish a numerical model of the transportation micro-environments in Jinan City, and the general Thermal climate index (UTCI) under different canopy ratio (CR) and leaf area density (LAD) under the southeast wind direction was calculated. Combined with the spatial distribution of temperature and relative humidity, the thermal comfort of the transportation micro-environments under different vegetation configurations was evaluated. The results showed that the street trees with H = 5 m and CR = 0.4 had the best cooling effect at 12:00 noon, and the temperature drop was 0.80ºC. The higher the tree height, the larger the tree crown, the worse the humidification effect, H = 5m, CR = 0.4 the best humidification effect, the moisture increment can reach 0.76%. Street trees with H = 5 m and CR = 0.6 showed the best performance in improving thermal comfort, reducing UTCI by 2.01ºC. When LAD increased by 0.5, the temperature increased by 23.75% to 24.90%, and the cooling and humidification effects of street trees with LAD = 0.5 were the most significant. Under LAD = 0.5, LAD = 1, LAD = 1.5 and LAD = 2, the UTCI of street trees was increased, and the average UTCI value ranged from 38.28°C to 39.13°C. The research results can provide references for the planning and design of road green plants, thermal comfort improvement, microclimate regulation and ecological benefit enhancement in the sustainable development of cities.