Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere

Abstract Cool materials and rooftop vegetation help achieve urban heating mitigation as they can reduce building cooling demands. This study assesses the cooling potential of different mitigation technologies using Weather Research and Forecasting (WRF)- taking case of a tropical coastal climate in...

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Main Authors: Ansar Khan, Laura Carlosena, Samiran Khorat, Rupali Khatun, Debashish Das, Quang-Van Doan, Rafiq Hamdi, Sk Mohammad Aziz, Hashem Akbari, Mattheos Santamouris, Dev Niyogi
Format: Article
Language:English
Published: Springer 2023-08-01
Series:Computational Urban Science
Subjects:
Online Access:https://doi.org/10.1007/s43762-023-00101-1
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author Ansar Khan
Laura Carlosena
Samiran Khorat
Rupali Khatun
Debashish Das
Quang-Van Doan
Rafiq Hamdi
Sk Mohammad Aziz
Hashem Akbari
Mattheos Santamouris
Dev Niyogi
author_facet Ansar Khan
Laura Carlosena
Samiran Khorat
Rupali Khatun
Debashish Das
Quang-Van Doan
Rafiq Hamdi
Sk Mohammad Aziz
Hashem Akbari
Mattheos Santamouris
Dev Niyogi
author_sort Ansar Khan
collection DOAJ
description Abstract Cool materials and rooftop vegetation help achieve urban heating mitigation as they can reduce building cooling demands. This study assesses the cooling potential of different mitigation technologies using Weather Research and Forecasting (WRF)- taking case of a tropical coastal climate in the Kolkata Metropolitan Area. The model was validated using data from six meteorological sites. The cooling potential of eight mitigation scenarios was evaluated for: three cool roofs, four green roofs, and their combination (cool-city). The sensible heat, latent heat, heat storage, 2-m ambient temperature, surface temperature, air temperature, roof temperature, and urban canopy temperature was calculated. The effects on the urban boundary layer were also investigated. The different scenarios reduced the daytime temperature of various urban components, and the effect varied nearly linearly with increasing albedo and green roof fractions. For example, the maximum ambient temperature decreased by 3.6 °C, 0.9 °C, and 1.4 °C for a cool roof with 85% albedo, 100% rooftop vegetation, and their combination. The cost of different mitigation scenarios was assumed to depend on the construction options, location, and market prices. The potential for price per square meter and corresponding temperature decreased was related to one another. Recognizing the complex relationship between scenarios and construction options, the reduction in the maximum and minimum temperature across different cool and green roof cases were used for developing the cost estimates. This estimate thus attempted a summary of the price per degree of cooling for the different potential technologies. Higher green fraction, cool materials, and their combination generally reduced winds and enhanced buoyancy. The surface changes alter the lower atmospheric dynamics such as low-level vertical mixing and a shallower boundary layer and weakened horizontal convective rolls during afternoon hours. Although cool materials offer the highest temperature reductions, the cooling resulting from its combination and a green roof strategy could mitigate or reverse the summertime heat island effect. The results highlight the possibilities for heat mitigation and offer insight into the different strategies and costs for mitigating the urban heating and cooling demands.
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spelling doaj.art-24340c67312945d9a353f1ded885e5ed2023-11-26T12:37:01ZengSpringerComputational Urban Science2730-68522023-08-013113110.1007/s43762-023-00101-1Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphereAnsar Khan0Laura Carlosena1Samiran Khorat2Rupali Khatun3Debashish Das4Quang-Van Doan5Rafiq Hamdi6Sk Mohammad Aziz7Hashem Akbari8Mattheos Santamouris9Dev Niyogi10Department of Geography, Lalbaba College, University of CalcuttaEngineering Department, Public University of Navarre (UPNA)School of Environmental Studies, Jadavpur UniversitySchool of Environmental Studies, Jadavpur UniversityDepartment of Architecture, Jadavpur UniversityCentre for Computational Sciences, University of TsukubaRoyal Meteorological Institute of BelgiumDepartment of Chemistry, Narajole Raj College, Vidyasagar UniversityHeat Island Group, Department of Building, Civil, and Environmental Engineering, Concordia UniversityDepartment of Built Environment, University of New South WalesDepartment of Geological Sciences, Jackson School of Geosciences, Department of Civil, Architectural, and Environmental Engineering, Cockrell School of Engineering, University of TexasAbstract Cool materials and rooftop vegetation help achieve urban heating mitigation as they can reduce building cooling demands. This study assesses the cooling potential of different mitigation technologies using Weather Research and Forecasting (WRF)- taking case of a tropical coastal climate in the Kolkata Metropolitan Area. The model was validated using data from six meteorological sites. The cooling potential of eight mitigation scenarios was evaluated for: three cool roofs, four green roofs, and their combination (cool-city). The sensible heat, latent heat, heat storage, 2-m ambient temperature, surface temperature, air temperature, roof temperature, and urban canopy temperature was calculated. The effects on the urban boundary layer were also investigated. The different scenarios reduced the daytime temperature of various urban components, and the effect varied nearly linearly with increasing albedo and green roof fractions. For example, the maximum ambient temperature decreased by 3.6 °C, 0.9 °C, and 1.4 °C for a cool roof with 85% albedo, 100% rooftop vegetation, and their combination. The cost of different mitigation scenarios was assumed to depend on the construction options, location, and market prices. The potential for price per square meter and corresponding temperature decreased was related to one another. Recognizing the complex relationship between scenarios and construction options, the reduction in the maximum and minimum temperature across different cool and green roof cases were used for developing the cost estimates. This estimate thus attempted a summary of the price per degree of cooling for the different potential technologies. Higher green fraction, cool materials, and their combination generally reduced winds and enhanced buoyancy. The surface changes alter the lower atmospheric dynamics such as low-level vertical mixing and a shallower boundary layer and weakened horizontal convective rolls during afternoon hours. Although cool materials offer the highest temperature reductions, the cooling resulting from its combination and a green roof strategy could mitigate or reverse the summertime heat island effect. The results highlight the possibilities for heat mitigation and offer insight into the different strategies and costs for mitigating the urban heating and cooling demands.https://doi.org/10.1007/s43762-023-00101-1Urban heatingCool roofsGreen roofsCool cityWRF/SLUCMBuilding cooling demand
spellingShingle Ansar Khan
Laura Carlosena
Samiran Khorat
Rupali Khatun
Debashish Das
Quang-Van Doan
Rafiq Hamdi
Sk Mohammad Aziz
Hashem Akbari
Mattheos Santamouris
Dev Niyogi
Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
Computational Urban Science
Urban heating
Cool roofs
Green roofs
Cool city
WRF/SLUCM
Building cooling demand
title Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
title_full Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
title_fullStr Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
title_full_unstemmed Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
title_short Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
title_sort urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere
topic Urban heating
Cool roofs
Green roofs
Cool city
WRF/SLUCM
Building cooling demand
url https://doi.org/10.1007/s43762-023-00101-1
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