Study on Urban Greening Method for Mitigation of Thermal Environment based on Distribution of Daily Solar Radiation Using 3D CAD

Abstract

In this study, urban greening method was proposed for mitigation of thermal environment based on distribution of daily solar radiation using 3D CAD. This approach is verified to an actual urban block on the center of Tokyo, which applied to planned development design system. And the feasible greening plan, considering the live loads, legal conditions and daylight conditions for vegetation growth, was constructed. And the appropriate greening plan was constructed using distribution of daily solar radiation. Then numerical simulations are conducted for the present conditions, the feasible greening plan and for the appropriate greening plan. And three indices were used to evaluate the outdoor thermal environment: surface temperature distribution, Heat Island Potential (HIP) as an index of the sensible heat flow rate on all surfaces in an urban block, and mean radiant temperature distributions at a height of 1.5 m as an index to evaluate the thermal comfort of outdoor living. After all considerations, it was revealed that the sensible heat flux, based on the appropriate greening plan, would be decreased by nearly 50% in maximum from the present condition. In addition, MRT distribution of the appropriate greening plan is vicinity to the air temperature for most of the day.