Present Situation of Outdoor Wind Environmental Issues in Japan
キーワード:
air pollution,
CFD,
heat island phenomenon,
pedestrian wind environment,
wind tunnel experiment
2009 年 13 巻 2 号 p. 179-188
詳細
2009 年 13 巻 2 号 p. 179-188
This article introduces the current status of outdoor environmental issues in Japan. The outdoor environment is greatly affected by various wind conditions, commonly classified as strong winds and weak winds. Strong winds around high-rise buildings have been a social issue for over 30 years in Japan. Wind tunnel experiments have been conducted to assess the environmental impact of strong winds at the pedestrian level and are regarded as the most reliable prediction method. In recent years, the application of computational fluid dynamics (CFD) to this problem has been rapidly gaining popularity and acceptance. To ensure the reliability of CFD simulations, " AIJ guidelines for practical applications of CFD to pedestrian wind environments around buildings " was published in 2007.
On the other hand, weak wind conditions can also cause problems. Air pollution and the heat island phenomenon intensify when winds are weak. Owing to the restrictions on the emission of harmful substances from both facilities and automobiles, Japan’s outdoor air quality has been gradually improving. The annual averages of NO2, SO2, CO, and SPM concentrations have remained steady or gradually declined in recent years, but the compliance rates with the Environmental Quality Standards have been extremely low for photochemical oxidants. Heat island phenomenon currently occurs in most cities in Japan due to anthropogenic heating, poor urban ventilation and oversized artificial ground coverage areas. Several countermeasures have been taken by governmental authorities. Recent researches on urban heat islands in Japan are reviewed in the latter part of this article.
