Outdoor thermal performance of green roofs across multiple time scales: A case study in subtropical China

Xiandi Zheng, Fanhua Kong, Haiwei Yin, Ariane Middel, Hongqing Liu, Ding Wang, Tao Sun, Itamar Lensky

Research output: Contribution to journalArticlepeer-review

Abstract

In recent years, roof greening technologies have been developed and implemented worldwide, as green roofs are an effective nature-based solution for alleviating outdoor heat and reducing building energy costs. While most observational green roof studies have investigated the cooling effect of model or test plots, few studies have conducted full-scale measurements; however, to guide green roof implementation, the thermal performance of full-scale roofs is crucial. This experimental study explored the ability of extensive green roofs to reduce outdoor temperatures on multiple time scales. The outdoor cooling effect of green roofs and the main factors that drive its performance were analyzed using long-term observational data collected from May 2016 to April 2019 in Nanjing, China. The results suggest that the cooling effect of green roofs exhibits significant diurnal, seasonal, annual, and vertical trends, and that the cooling performance across different time scales corresponds to weather and soil characteristics. The best cooling effect occurred at a height of 60 cm. The green roof displayed a temporary diurnal warming effect but had a good cooling effect on a seasonal time scale, with the largest amount of cooling occurring during the summer (average of 0.28 °C). The findings of this study can support the development, management, and maintenance of green roofs in subtropical areas.

Original languageEnglish (US)
Article number102909
JournalSustainable Cities and Society
Volume70
DOIs
StatePublished - Jul 2021

Keywords

  • Extensive green roof
  • Influencing factors
  • Multiple time scales
  • Outdoor thermal performance
  • Subtropical monsoon climate

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Civil and Structural Engineering
  • Renewable Energy, Sustainability and the Environment
  • Transportation

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