木漏れ日に着目した単木落葉樹の日射遮蔽に関する数値解析

概要

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In order to create more attractive urban spaces by greening, we need to take into account the various effects of greenery, for example solar shading of tree crown and cooling effect by transpiration, when designing green urban spaces. The purpose of this study is to develop numerical tree model of a deciduous tree for simulating the effects of solar shading by tree crown on the surface temperature, brightness distribution and illuminance distribution under tree crown. As a fundamental study, this paper investigates relationship between tree geometry and solar transmittance using the CG tree model. The solar transmittance ratio is determined as the ratio of sunlight through a tree into the tree shadow. Several tree species and variation are created by a CGsoftware. Hourly the solar transmittance ratio is calculated by the ray-tracing method using the CG model. The relationship between the tree geometry depending on tree species and the solar transmittance ratio is analyzed. The result shows that the solar transmittance ratio of Prunus x yedoensis and Platanus x acarifolia have no relationship to these factors, although the ratio of Zelkova serrata, which has similar geometry type to plant community, is depended on LAI. These indicate that a tree model for solar transmittance need several parameters such as LAI, size of leaf and density of branch.
社団法人　日本造園学会の論文