Comparative Evaluation of the Effectiveness of Cool Roofs in the Hot and Dry Climate of Iran

Subject Areas : Architecture

Shokouh sadat Asadollahi ¹ , Mansoureh Tahbaz ² , Niloufar Nikghadam ³ , Mahnaz Mahmoudi Zarandi ⁴

1 -
2 -
3 -
4 -

Received: 2025-03-01 Accepted : 2025-07-09 Published : 2025-07-14

Keywords: Cool roofs, Hot and dry climates, educational buildings, Sustainability, Passive cooling strategies, Energy efficiency, Thermal comfort,

Abstract :

Escalating urban heat island effects and rising energy demands in Iran's hot, dry climate pose a serious challenge for educational buildings, where high occupant density intensifies cooling needs and operational costs. This research addresses the urgency of adopting cool roof technologies—such as reflective coatings, green roofs, high-albedo materials, and radiative cooling roofs—to mitigate extreme indoor temperatures, reduce carbon footprints, and enhance student and staff well-being. Drawing on empirical data, simulation models, and a comprehensive literature review, we employ a weighted-scoring framework that evaluates each technology's thermal performance, energy savings, cost factors, durability, and environmental impact. Findings reveal that while radiative cooling roofs offer the greatest potential for reducing cooling loads (up to 30–40%) and maintaining comfortable indoor temperatures, they demand more advanced materials and higher initial investment. Green roofs yield substantial insulation and environmental benefits, but are limited by water scarcity and elevated setup costs. Conversely, reflective coatings and high-albedo materials strike a balance between effectiveness and affordability, making them viable for retrofits in budget-constrained educational facilities. The results underscore the need for context-specific solutions that consider local climate, water resources, building typology, and policy incentives. By clarifying the strengths and trade-offs of each cool roof approach, this study provides actionable guidance for architects, policymakers, and school administrators seeking sustainable and cost-effective interventions. Future research should focus on long-term performance monitoring, integrating complementary passive strategies (e.g., shading, natural ventilation), and developing localized materials tailored to resource-limited contexts.

References:

Adilkhanova, I., Santamouris, M., & Yun, G. Y. (2023). Coupling urban climate modeling and city-scale building energy simulations with the statistical analysis: Climate and energy implications of high albedo materials in Seoul. Energy and Buildings, 290, 113092. https://doi.org/10.1016/j.enbuild.2023.113092
Anand, J., Sailor, D. J., & Baniassadi, A. (2021). The relative role of solar reflectance and thermal emittance for passive daytime radiative cooling technologies applied to rooftops. Sustainable Cities and Society, 65, 102612. https://doi.org/10.1016/j.scs.2020.102612
Andric, I., Kamal, A., & Al-Ghamdi, S. G. (2020). Efficiency of green roofs and green walls as climate change mitigation measures in extremely hot and dry climate: Case study of Qatar. Energy Reports, 6, 2476–2489. https://doi.org/10.1016/j.egyr.2020.09.006
Ashtari, B., Yeganeh, M., Bemanian, M., & Vojdani Fakhr, B. (2021). A conceptual review of the potential of cool roofs as an effective passive solar technique: Elaboration of benefits and drawbacks. Frontiers in Energy Research, 9, 738182. https://doi.org/10.3389/fenrg.2021.738182
Ben Cheikh, H., & Bouchair, A. (2004). Passive cooling by evapo-reflective roof for hot, dry climates. Renewable Energy, 29(11), 1877–1886. https://doi.org/10.1016/j.renene.2003.12.021
Bevilacqua, P. (2021). The effectiveness of green roofs in reducing building energy consumptions across different climates. A summary of literature results. Renewable and Sustainable Energy Reviews, 151, 111523. https://doi.org/10.1016/j.rser.2021.111523
Boixo, S., Diaz-Vicente, M., Colmenar, A., & Castro, M. A. (2012). Potential energy savings from cool roofs in Spain and Andalusia. Energy, 38(1), 425–438. https://doi.org/10.1016/j.energy.2011.11.009
Cavadini, G. B., & Cook, L. M. (2021). Green and cool roof choices integrated into rooftop solar energy modelling. Applied Energy, 296, 117082. https://doi.org/10.1016/j.apenergy.2021.117082
Chen, J., & Lu, L. (2021). Comprehensive evaluation of thermal and energy performance of radiative roof cooling in buildings. Journal of Building Engineering, 33, 101631. https://doi.org/10.1016/j.jobe.2020.101631
Chen, J., Lu, L., Gong, Q., Lau, W. Y., & Cheung, K. H. (2021). Techno-economic and environmental performance assessment of radiative sky cooling-based super-cool roof applications in China. Energy Conversion and Management, 245, 114621. https://doi.org/10.1016/j.enconman.2021.114621
Elnabawi, M. H., Alhumaidi, A., Osman, B., & Alshehhi, R. (2022). Cool roofs in hot climates: A conceptual review of modelling methods and limitations. Buildings, 12(11), 1968. https://doi.org/10.3390/buildings12111968
Feng, J., Saliari, M., Gao, K., & Santamouris, M. (2022). On the Cooling Energy Conservation Potential of Super Cool Roofs. Energy and Buildings, 264, 112076. https://doi.org/10.1016/j.enbuild.2022.112076
Freidooni, F., Freidooni, S., & Gandomkar, A. (2022). Climatic compatible future cities locating approach to less non-renewable energy consumption. Journal of Urban Management and Energy Sustainability, 4(2). https://doi.org/10.22034/jumes.2022.1982956.1101
Garshasbi, S., Feng, J., Paolini, R., Jonathan Duverge, J., Bartesaghi-Koc, C., Arasteh, S., Khan, A., & Santamouris, M. (2023). On the energy impact of cool roofs in Australia. Energy and Buildings, 278, 112577. https://doi.org/10.1016/j.enbuild.2022.112577
He, Y., Yu, H., Ozaki, A., & Dong, N. (2020). Thermal and Energy Performance of Green Roofs and Cool Roofs: A Comparison Study in the Shanghai Area. Journal of Cleaner Production, 267, 122205. https://doi.org/10.1016/j.jclepro.2020.122205
Heidari, S., & Azizi, M. (2019). Evaluation of thermal comfort in urban areas. Journal of Urban Management and Energy Sustainability, 1(1). https://doi.org/10.22034/ijumes.2019.01.01.005
Hessari, P., & Seyf Shojaee, M. (2022). Evaluation of the optimal form of educational building based on energy consumption (Case study: Torbat Heydarieh city). Journal of Urban Management and Energy Sustainability, Online First. https://doi.org/10.22034/jumes.2021.558191.1081
Hosseini, M., & Akbari, H. (2016). Effect of Cool Roofs on Commercial Buildings' Energy Use in Cold Climates. Energy and Buildings, 114, 143–155. https://doi.org/10.1016/j.enbuild.2015.05.050
Jamshidi, F., Ziyari, Y. A., Zarabadii, Z., & Bahmanpour, H. (2024). Local model of urban green infrastructure in the direction of sustainability in the urban complex of Tehran city. Journal of Urban Management and Energy Sustainability, Online First. https://doi.org/10.22034/jumes.2024.2016822.1184
Krarti, M., Kreider, J. F., Cohen, D., & Curtiss, P. (1998). Estimation of energy savings for building retrofits using neural networks. Journal of Solar Energy Engineering, 120(3), 211–216. https://doi.org/10.1115/1.2888071.
Rawat, M., & Singh, R. N. (2022). A study on the comparative review of cool roof thermal performance in various regions. Energy and Built Environment, 3(3), 327–347. https://doi.org/10.1016/j.enbenv.2021.03.001.
Saber, H. H. (2022). Hygrothermal performance of cool roofs with reflective coating material subjected to hot, humid, and dusty climate. Journal of Building Physics, 45(4), 457–481. https://doi.org/10.1177/17442591211001408
Torgal, F. P., Czarnecki, L., Pisello, A. L., Cabeza, L. F., & Granqvist, C. G. (Eds.). (2021). Eco-efficient materials for reducing cooling needs in buildings and construction: Design, properties and applications. Woodhead Publishing, an imprint of Elsevier.
Virk, G., Jansz, A., Mavrogianni, A., Mylona, A., Stocker, J., & Davies, M. (2014). The effectiveness of retrofitted green and cool roofs at reducing overheating in a naturally ventilated office in London: Direct and indirect effects in current and future climates. Indoor and Built Environment, 23(3), 504–520. https://doi.org/10.1177/1420326X14527976.
Wang, N., Lv, Y., Zhao, D., Zhao, W., Xu, J., & Yang, R. (2022). Performance Evaluation of Radiative Cooling for Commercial-Scale Warehouses. Materials Today Energy, 24, 100927. https://doi.org/10.1016/j.mtener.2021.100927
Wang, X., Li, H., & Sodoudi, S. (2022). The effectiveness of cool and green roofs in mitigating urban heat island and improving human thermal comfort. Building and Environment, 217, 109082. https://doi.org/10.1016/j.buildenv.2022.109082
Xiao, S., Cheng, D., Hu, N., Wang, Y., Zhang, H., Gou, Y., Li, X., & Lv, Z. (2023a). Experiments on the thermal performance and service life of three high-albedo roof materials in Nanjing, China. Journal of Applied Meteorology and Climatology, 62(12), 1909–1920. https://doi.org/10.1175/JAMC-D-23-0031.1.
Xiao, S., Cheng, D., Hu, N., Wang, Y., Zhang, H., Gou, Y., Li, X., & Lv, Z. (2023b). Experiments on the thermal performance and service life of three high-albedo roof materials in Nanjing, China. Journal of Applied Meteorology and Climatology, 62(12), 1909–1920. https://doi.org/10.1175/JAMC-D-23-0031.1
Xiao, S., Cheng, D., Hu, N., Wang, Y., Zhang, H., Gou, Y., Li, X., & Lv, Z. (2023c). Experiments on the thermal performance and service life of three high-albedo roof materials in Nanjing, China. Journal of Applied Meteorology and Climatology, 62(12), 1909–1920. https://doi.org/10.1175/JAMC-D-23-0031.1.
Xu, T., Sathaye, J., Akbari, H., Garg, V., & Tetali, S. (2012). Quantifying the direct benefits of cool roofs in an urban setting: Reduced cooling energy use and lowered greenhouse gas emissions. Building and Environment, 48, 1–6. https://doi.org/10.1016/j.buildenv.2011.08.011.
Yang, L., Fu, R., He, W., He, Q., & Liu, Y. (2020). Adaptive thermal comfort and climate-responsive building design strategies in dry–hot and dry–cold areas: Case study in Turpan, China. Energy and Buildings, 209, 109678. https://doi.org/10.1016/j.enbuild.2019.109678
Yazdani, H., & Baneshi, M. (2021). Building energy comparison for dynamic cool roofs and green roofs under various climates. Solar Energy, 230, 764–778. https://doi.org/10.1016/j.solener.2021.10.076.