Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance

The Solar Reflectance Index (SRI) is a standardized metric used to assess the reflective properties of materials in relation to solar radiation and their capacity to emit absorbed heat, particularly within the infrared spectrum. Materials with high SRI values, often referred to as “cool materials”,...

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Main Authors: Zahra Jandaghian, Michael Lacasse, Abhishek Gaur
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Buildings
Subjects:
Online Access:https://www.mdpi.com/2075-5309/15/6/888
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author Zahra Jandaghian
Michael Lacasse
Abhishek Gaur
author_facet Zahra Jandaghian
Michael Lacasse
Abhishek Gaur
author_sort Zahra Jandaghian
collection DOAJ
description The Solar Reflectance Index (SRI) is a standardized metric used to assess the reflective properties of materials in relation to solar radiation and their capacity to emit absorbed heat, particularly within the infrared spectrum. Materials with high SRI values, often referred to as “cool materials”, contribute to ambient temperature regulation, Urban Heat Island (UHI) mitigation, and cooling energy demand reduction. The effectiveness of SRI depends on factors such as solar incidence angles, intrinsic material properties, and varying environmental conditions. Accurate assessments require the implementation of standardized testing and rating methodologies. This paper reviews and compares North American (ASTM E1980, ASTM C1549, ASTM C1371) and European (EN 15976) standards to determine SRI, focusing on the impacts of weathering and climatic factors on material aging. The study highlights the inadequacy of current practices, which typically measure SRI after only three years of exposure, and advocates for long-term performance monitoring across diverse climates. Key findings reveal that high-SRI materials can reduce surface temperatures by up to 20 °C, significantly lowering cooling energy demands. The study recommends the development of comparable standards to measure solar reflectivity on vertical surfaces, emphasizing the importance of assessing long-term performance across various climatic conditions. Findings underscore the importance of advanced modeling, innovative materials development, and effective maintenance strategies to extend the durability and efficacy of cool materials. The novelty of this work lies in its comprehensive framework for SRI assessment, integrating advanced modeling, innovative materials development, and real-world performance monitoring. This study provides actionable insights for policymakers, urban planners, and architects to enhance building energy efficiency and urban resilience.
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spelling doaj-art-28124b4fa5a247998f0d73ab604591e92025-08-20T02:11:15ZengMDPI AGBuildings2075-53092025-03-0115688810.3390/buildings15060888Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term PerformanceZahra Jandaghian0Michael Lacasse1Abhishek Gaur2Construction Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, CanadaConstruction Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, CanadaConstruction Research Centre, National Research Council Canada, Ottawa, ON K1A 0R6, CanadaThe Solar Reflectance Index (SRI) is a standardized metric used to assess the reflective properties of materials in relation to solar radiation and their capacity to emit absorbed heat, particularly within the infrared spectrum. Materials with high SRI values, often referred to as “cool materials”, contribute to ambient temperature regulation, Urban Heat Island (UHI) mitigation, and cooling energy demand reduction. The effectiveness of SRI depends on factors such as solar incidence angles, intrinsic material properties, and varying environmental conditions. Accurate assessments require the implementation of standardized testing and rating methodologies. This paper reviews and compares North American (ASTM E1980, ASTM C1549, ASTM C1371) and European (EN 15976) standards to determine SRI, focusing on the impacts of weathering and climatic factors on material aging. The study highlights the inadequacy of current practices, which typically measure SRI after only three years of exposure, and advocates for long-term performance monitoring across diverse climates. Key findings reveal that high-SRI materials can reduce surface temperatures by up to 20 °C, significantly lowering cooling energy demands. The study recommends the development of comparable standards to measure solar reflectivity on vertical surfaces, emphasizing the importance of assessing long-term performance across various climatic conditions. Findings underscore the importance of advanced modeling, innovative materials development, and effective maintenance strategies to extend the durability and efficacy of cool materials. The novelty of this work lies in its comprehensive framework for SRI assessment, integrating advanced modeling, innovative materials development, and real-world performance monitoring. This study provides actionable insights for policymakers, urban planners, and architects to enhance building energy efficiency and urban resilience.https://www.mdpi.com/2075-5309/15/6/888solar reflectance index (SRI)cool materialsurban heat island (UHI) mitigationdurability testingmaterials weathering and aging
spellingShingle Zahra Jandaghian
Michael Lacasse
Abhishek Gaur
Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance
Buildings
solar reflectance index (SRI)
cool materials
urban heat island (UHI) mitigation
durability testing
materials weathering and aging
title Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance
title_full Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance
title_fullStr Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance
title_full_unstemmed Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance
title_short Solar Reflectance Index of Building Envelope Materials: A Comparative Review of North American and European Standards and Long-Term Performance
title_sort solar reflectance index of building envelope materials a comparative review of north american and european standards and long term performance
topic solar reflectance index (SRI)
cool materials
urban heat island (UHI) mitigation
durability testing
materials weathering and aging
url https://www.mdpi.com/2075-5309/15/6/888
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AT abhishekgaur solarreflectanceindexofbuildingenvelopematerialsacomparativereviewofnorthamericanandeuropeanstandardsandlongtermperformance