Tokyo Heat Island Adaptation Measures

Abstract

“It is difficult to improve the quality of life because Tokyo is already so developed. Tokyo has come about without any urban planning,” said former Tokyo Governor Shintaro Ishihara. The heat island effect in Tokyo, which is one of the most densely populated areas in Asia, has been intensifying in recent years. In order to solve this problem, urban and regional planning must be used to devise the layout of buildings and land cover, and appropriate countermeasure need to be taken to improve the environmental. This chapter describes recent efforts in Tokyo to secure the flow of wind through urban spaces and actual trials for cooling outdoor apparent temperatures. Section 6.1 outlines the current state of the heat island effect in Tokyo. It illustrates the number of tropical nights in Tokyo and temperature conditions, and explains the effect on the heat island phenomenon, people and the urban environment. In Sect. 6.2, the sensible temperature in urban spaces and the analyzing methods are described. A person standing in urban spaces receives various heat from the sun, soil surface, building walls and atmosphere. We developed a numerical model of radiant heat exchange in urban spaces considering the complex 3D geometries formed by buildings and the location of surface materials to estimate the district plans that lower sensible temperatures. This analysis method was applied to a marathon course in the Ginza district, and the thermal impact on people through various cooling measures such as planting trees, water sprinklers and road materials were discussed. Another topic is the case of a bus stop in a semi-open outdoor space equipped with a cooling bench using groundwater. It is unique in that physiological and psychological factors such as heart rates and thermal physiological effects were surveyed with thermal conditions. Section 6.3 is about wind paths. The Tokyo wind path mapping method featuring sea wind is explained and actual urban projects were introduced. Additionally, a quantitative analysis was performed to find a relation between the wind path securement method and sensible temperatures.