Simulation study of the influence of different urban canyons element to the canyon thermal environment

Heat island is a big issue for large cities especially located in hot and moist climate in Asian countries. The phenomenon is severer in an urban canyon because of surrounding highrise buildings causing little ventilation and heat dissipation from traffic. The first purpose of this study is to investigate thermal environment of a main street in Osaka by intensive  measurement in the summer of 2006. Osaka is the second largest city and suffers from the most severe heat island in Japan. The second purpose is to propose several fundamental renovations and a composite renovation for the improvement of thermal environment in the canyon and verify the efficiency of the measures by CFD simulation. It was found that modifications in the building height along the street and ground surface materials, and increase of quantity of green can improve thermal environment to the level of 2.0 K reduction in SET* in maximum.