Study on optimum arrangement of trees for design of pleasant outdoor environment using multi-objective genetic algorithm and coupled simulation of convection, radiation and conduction

Outdoor thermal environments represented by the urban heat-island phenomenon that accompanies urbanization have become markedly worse in recent years during summer in Japan. Many researches have been conducted into the effect of plants on the outdoor thermal environment during summer. However, the optimum design system for such plants has not been established yet. In this paper, (1) a multi-objective optimum design method for a comfortable outdoor thermal urban environment is developed using a multi-objective genetic algorithm (MOGA); and (2) in order to examine the validity of the proposed optimum design method, two cases are analyzed: a single-objective optimization problem from the viewpoint of human's comfort and a multi-objective optimization problem involving various factors, such as the landscape, outdoor thermal environment, and economy. The results of this method show the trade-off relationship between two or more objective functions, and the Pareto-optimal solution set is achieved.