Abstract
Urban informal settlements face severe heat stress yet lack affordable cooling solutions. We engage two communities in Bihar, India, to test two low-cost, rapidly deployable interventions. Using over 2 million minute-level temperature observations, we find both interventions improve thermal comfort in informal dwellings: radiant foils lower indoor temperatures by 1.24 °C, whereas Mylar blankets achieve a reduction of 0.97 °C. These findings demonstrate a scalable strategy for climate adaptation in vulnerable urban communities.
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Data availability
The data used in this study are available via Github at https://github.com/City-Syntax/informal-settlements-study.
Code availability
The code used in this study is available via Github at https://github.com/City-Syntax/informal-settlements-study.
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Acknowledgements
This research is supported by the National University of Singapore Start-up Grant FY2025 (Y.Q.A.).
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Y.Q.A. and S. conceptualized the study. Field work was conducted by S. Data were processed by S. and Y.Q.A. Y.Q.A. drafted the original manuscript, supervised the project and acquired funding. All authors analyzed the data and critically reviewed and edited the manuscript.
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Nature Cities thanks Anamika Shreevastava, Graziano Salvalai and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Extended data
Extended Data Fig. 1 Representative housing typologies and site conditions across the two informal settlement study sites in Patna, Bihar.
Photographs illustrate the built environment of the study sites, characterized by high-density living and precarious construction. These sites were selected to represent typical informal housing conditions in the region.
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Ang, Y.Q., Sparsh, Wang, T. et al. Low-cost interventions for heat stress mitigation in urban informal settlements. Nat Cities 3, 22–27 (2026). https://doi.org/10.1038/s44284-025-00370-3
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DOI: https://doi.org/10.1038/s44284-025-00370-3
