The cooling effect of green infrastructure in mitigating nocturnal urban heat islands: a case study of Yoyogi Park and Meiji Jingu Shrine in Tokyo

Abstract

This study assesses the implementation of green infrastructure plans to mitigate the effects of nocturnal urban heat islands in Yoyogi Park and Meiji Jingu Shrine in the surrounding Shibuya urban area, Tokyo. The study revealed there to be a strong correlation between green spaces and air temperature (Ta) during the early morning, where a Ta inversion occurred tens of metres from the ground due to radiant cooling. Air (park breeze) flowed through valleys and gaps between mid-high-rise buildings. Based on wind simulation results, three green infrastructure plans were created to connect the Yoyogi Park green space and the airflow area with the green network. Computational fluid dynamics (CFD) modelling and thermal simulations clarified a cooling effect of the green infrastructure plans on the surrounding Shibuya urban area. This will be useful for consensus building among the Shibuya population and decision making regarding the City Master Plan, and other urban areas.

Keywords:

• Urban green space
• green infrastructure
• urban park
• air flow
• cooling effect
• urban heat island
• remote sensing

Acknowledgements

The authors are grateful to Professor Emeritus Toshitaro Minomo for their support in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Sumitomo Foundation Environmental Research Grant project under [Grant No. 173242].

Notes on contributors

Teruaki Irie

Teruaki Irie was born in Japan in 1971. He is a professor at the Tokyo University of Agriculture and a member of the Faculty of Regional Environment Science. He obtained his Doctorate in Landscape Architecture (Ph.D.) from the Tokyo University of Agriculture in 2003. He currently belongs to the Laboratory of Regional Environment Planning and Design, and teaches landscape, city and country planning. He was a visiting scholar at Aarhus University in Denmark from September 2017 to August 2018. He is interested in green infrastructure planning, green and grey integration, green space networks, the benefits of urban parks, collaborative and participatory planning for social inclusion.