●Research Trends and Results

Development of technologies for city planning to takeeffective urban heat island countermeasures
KAGIYA Koji (Ph. D.), Senior Researcher
Urban Planning Department, Urban Development Division
ASHIE Yasunobu (Dr. Eng.), Head
Building Department, Environmental and Equipment Standards Division(Key words) Urban Heat island, ventilation path, simulation, city planning
1. Introduction
The NILIM has been, through cooperative researchwith the Building Research Institute, conducting aresearch project jointly with the concerned bureaus ofthe Ministry of Land, Infrastructure, Transport andTourism (MLIT) to provide simulation tools and urban
planning guidelines to local governments in order toenable them to systematically implement effective
urban heat island (UHI) countermeasures.
2. Ventilation path as a heat island countermeasure
In order to clarify the actual state and effectivenessof ventilation paths, which have attracted attention asa UHI countermeasure, we are performing large-scalemeteorological observations at 190 locations on streets
and rooftops of buildings in central and bay area inTokyo and carrying out numerical simulations using
super computer.
It has, for example, been predicted that as the resultof creation of a ventilation path accompanying
large-scale redevelopment around Tokyo Station,
airflow will improve, lowering the air temperature byup to 2°C (Fig. 1) over a wide area.

effects of district scale countermeasures. This software
has been used by local governments such as Chiyoda
Ward in Tokyo, Osaka City, and Kita-kyushu City.
And an environmental atlas called Climatic Atlas ofUrban Environments was trial prepared withnumerical simulations visualizing the thermal
environment including air temperature distribution andairflow etc. as reference information for city planning.
Figure 2 is an example of a prototype based on thecountermeasure effects of ventilation path etc.
Reduction of artificial heat exhaust (by conserving
energy consumed by air-conditioners/ introducing adistrict heating/cooling system)
Restoration of vegetation (planting roadside trees), etc.
Ventilation Path (class 2)
Ensuring open space andgreening buildings and groundsurface

Ensuring open space andgreening buildings andground surface

Ventilation
Path (class 2)

Figure 2. Example of a Prototype of Climatic Atlas for
Urban Environment for City Planning
4. Achievements and future developments
Its achievements have been reflected to MLIT’s
Low Carbon City Development Guidance, city
planning guidelines or UHI countermeasure plans ofseveral local governments and a future image of a city
by a local community development committee.
The future aim is to reflect in the guidelines for
operation of city planning of MLIT and spread of theuse of technologies which have been developed topromote countermeasures to be implemented
effectively linked with low-carbon city planning.

Figure 1. Example of a Simulation of theEffectiveness of a Ventilation Path3. Development of technologies for urban planning
To enable regional governments to predict various
countermeasure effects of greening, water retentive
paving, ventilation path and so on in city planning,super computer calculation programs have beencombined with personal computer software to be usedas practical simulation tools capable of predicting the[Reference]
1) Report on NILIM Project No. 20, Development ofSynthetic Evaluation Technologies for Improving
Urban Thermal Environment, January 2008
2) Technical Note of the NILIM, No. 583, High
resolution numerical simulation on the urban heatisland of the entire 23 wards of Tokyo using theearth simulator, March 2010