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Green roofs save energy in cities and fight regional climate change

Nature Cities volume 1, pages 238–249 (2024)Cite this article

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Abstract

Cities around the globe search for solutions to tackle the challenges of climate resilience and energy consumption. The potential of green roofs representing a nature-based solution in mitigating urban heat and related energy consumption at the urban scale is given limited attention. Here we apply a comprehensive framework integrating urban climate modeling, urban building energy modeling and statistical analysis with empirical data to address this research gap through a case study in Seoul. The findings highlight that the efficacy of nonirrigated extensive green roofs is significantly influenced by meteorological conditions, underscoring the importance of considering those factors in green-roof design and implementation. Moreover, the cooling effect of green-roof implementation at the urban scale causes monthly urban building energy use intensity reductions of up to 0.64 kWh m−2 (7.7%). The insights from this research have broad implications for cities around the world experiencing the challenges imposed by urban heat.

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Fig. 1: Diurnal variations of key meteorological variables in August 2018 for various green-roof scenarios.
Fig. 2: Urban climate variations across different green-roof scenarios.
Fig. 3: Variations in air and surface temperature for various green-roof scenarios on three different days in August 2018.
Fig. 4: Changes in meteorological variables on three different days in August 2018.
Fig. 5: Change in monthly EUI.
Fig. 6: Change in monthly EUI due to green-roof implementation for different building categories.

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Data availability

The ERA-Interim reanalysis dataset for WRF simulations was accessed from https://rda.ucar.edu/datasets/ds627.0/dataaccess/. Building properties such as total floor area, height and number of floors, essential for the development of the urban building energy model, were collected from the official building registry (https://open.eais.go.kr/main/main.do). The monthly records of gas and electricity consumption for Seoul were accessed from the local online repository66. The AWS meteorological data were downloaded from the Korea Meteorological Administration (KMA) database59. Source data are provided with this paper.

Code availability

The analysis of urban climate conditions was performed using the WRF model (version 4.3). The latest version of the WRF modeling system’s source code can be obtained from the public WRF-Release page on GitHub, accessible at https://github.com/wrf-model/WRF/releases. The UBEM was performed using CitySim Pro software (version as of 3 May 2021), developed at EPFL. The tool can be accessed from its official website at http://www.kaemco.ch/download.php. The results were graphed using OriginPro (version 2022b 9.9.5.167 (Academic)). The Python (version 3.10.9) script used for WRF output processing and conversion is available at the repository with identifier https://doi.org/10.6084/m9.figshare.24998669.

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Acknowledgements

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (no. 2020R1A2C1099611, G.Y.Y.). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (no. RS-2023-00217322, G.Y.Y.).

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Authors and Affiliations

  1. Department of Architectural Engineering, Kyung Hee University, Yongin, Republic of Korea

    Indira Adilkhanova & Geun Young Yun

  2. High Performance Architecture, School of Built Environment, University of New South Wales, Sydney, New South Wales, Australia

    Mat Santamouris

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  1. Indira Adilkhanova
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Contributions

I.A.: conceptualization, methodology, investigation, formal analysis, visualization, writing—original draft, and writing—review and editing. M.S.: conceptualization, methodology, supervision, and writing—review and editing. G.Y.Y.: conceptualization, methodology, funding acquisition, supervision, writing—original draft, and writing—review and editing.

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Correspondence to Geun Young Yun.

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Nature Cities thanks Marcel Ignatius, Abhinav Wadhwa and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Adilkhanova, I., Santamouris, M. & Yun, G.Y. Green roofs save energy in cities and fight regional climate change. Nat Cities 1, 238–249 (2024). https://doi.org/10.1038/s44284-024-00035-7

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