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Quantifying the energy impact of heat mitigation technologies at the urban scale

Nature Cities volume 1, pages 62–72 (2024)Cite this article

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Abstract

Advanced urban heat mitigation technologies that involve the use of super-cool materials combined with properly designed green infrastructure lower urban ambient and land surface temperatures and reduce cooling consumption at the city scale. Here we present the results of a large-scale heat mitigation project in Riyadh, Saudi Arabia. Daytime radiative coolers, as well as cool materials combined with irrigated or non-irrigated greenery, were used to design eight holistic heat mitigation scenarios. We assess the climatic impact of the scenarios as well as the corresponding energy benefits of 3,323 urban buildings. An impressive decrease of the peak ambient temperature of up to 4.5 °C is calculated, the highest reported urban ambient temperature reduction, and the annual sum of the differences in the ambient temperature against a standard temperature base (cooling degree hours) in the city decreases by up to 26%. We find that innovative urban heat mitigation strategies contribute to the remarkable cooling energy conservation by up to 16%, and the combined implementation of heat mitigation and energy adaptation technologies decreases the cooling demand by up to 35%.

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Fig. 1: The methodology followed.
Fig. 2: Cooling load of the buildings.
Fig. 3: Distribution of heat indicator.

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Data availability

All available data have been uploaded to https://datadryad.org/stash/share/vap65l0fE3EEwelUskC2XC7cN0y7qL55MaUjeEZeZcs and https://zenodo.org/records/10090715.

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Acknowledgements

We gratefully acknowledge the support of the Royal Commission of Riyadh City for their contribution to the project ‘Strategic study on urban heat and mitigation potential in Riyadh—Kingdom of Saudi Arabia Cooling Riyadh’.

Author information

Author notes

  1. Shamila Haddad

    Present address: School of Architecture, Design and Planning, University of Sydney, Sydney, New South Wales, Australia

  2. Kai Gao

    Present address: Institute of Future Cities, The Chinese University of Hong Kong, Shatin, Hong Kong

Authors and Affiliations

  1. School of Built Environment, Faculty of Arts, Design and Architecture, University of New South Wales, Sydney, New South Wales, Australia

    Shamila Haddad, Riccardo Paolini, Kai Gao & Mattheos Santamouris

  2. Building Technology and Urban Systems Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Wanni Zhang & Tianzhen Hong

  3. Royal Commission of Riyadh City, Riyadh, Saudi Arabia

    Muzahim Altheeb, Abdulrahman Al Mogirah & Abdullatif Bin Moammar

  4. Department of Geography, Lalbaba College, University of Calcutta, Kolkata, India

    Ansar Khan

  5. Department of Environmental Physics, National and Kapodistrian University of Athens, Athens, Greece

    Constantinos Cartalis & Anastasios Polydoros

  6. Anita Lawrence Chair in High Performance Architecture, University of New South Wales, Sydney, New South Wales, Australia

    Mattheos Santamouris

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Contributions

The project was led by M.S., who was responsible for designing the mitigation scenarios and analyzing the data. S.H. coordinated the energy study and analyzed the energy data. W.Z. and T.H. conducted the energy simulations, and K.G. handled the mesoscale simulations. R.P. conducted the local climatic analysis, and C.C. and A.P. focused on the composite heat risk indicator study and provided remote sensing data. A.K. contributed to the mesoscale simulations. M.A., A.A.M. and A.B. provided essential local data and supervised the study. The manuscript was collectively written by M.S. and S.H., with contributions from all authors.

Corresponding author

Correspondence to Mattheos Santamouris.

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The authors declare no competing interests.

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Nature Cities thanks Rafiq Hamdi, M. Abdul Mujeebu, and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Integrated supplementary information

Extended Data Fig. 1 The distribution of the annual cooling load of the buildings for the eight mitigation scenarios.

a) Reflective Riyadh, b) Very Reflective and Dry Riyadh, c) Very Reflective Riyadh, d) Green and Irrigated Riyadh, e) Green and Dry Riyadh, f) Very Green and Irrigated Riyadh, g) Very Green and Dry Riyadh, h) Very Reflective and Irrigated Riyadh.

Extended Data Table 1 Total Reduction of the total summer Cooling Load of the 3323 buildings
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Haddad, S., Zhang, W., Paolini, R. et al. Quantifying the energy impact of heat mitigation technologies at the urban scale. Nat Cities 1, 62–72 (2024). https://doi.org/10.1038/s44284-023-00005-5

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