Development of a planting model for creating street green spaces to improve the urban thermal environment

Cities around the world are working to increase canopy coverage within cities to 30%~ 40% for improving the urban thermal environment. This study developed an efficient and systematic roadside green space planting model aimed at improving the urban thermal environment, focusing on street canyons with low aspect ratios and high thermal stress. The criteria for multi-row planting and installation of vegetative median strips were established based on the width of the sidewalk and road. For street trees with a crown width of 8m, two-row planting showed the highest cooling effect for a sidewalk width of 6m, and three-row planting was identified as the most effective strategy for enhancing the thermal environment along sidewalks with a width of 10m. Additionally, it was shown that the installation of vegetated median strips was effective for roads with four or more lanes. These results are equally applicable to both east-west and north-south oriented street canyons.

Furthermore, solutions for the optimized planting method of multi-row planting and vegetated median strips were also presented. The spacing between street trees should be the same as or narrower than the crown width, and the width of the green strap should be as wide as possible to enhance the cooling effect. The multi-layer structural planting demonstrates that the structure of trees + subtrees + shrubs is the most effective for improving the thermal environment in both multi-row planting and vegetated median strips.

This study is expected that urban planners, designers, and other professionals who plan and design urban spaces will be able to increase the possibility of alleviating urban thermal environment problems by understanding the thermal environment improvement mechanism through green space creation and utilizing it in green space planning and design.