Effect of Aging on Solar Reflectance of White Cool Roof Coatings: Natural Weathering and the Influence on Building Energy Needs for Different Climate Conditions in Brazil

Kelen Almeida Dornelles (University of Sao Paulo (USP), Institute of Architecture and Urbanism, Avenida Trabalhador São-Carlense, 400, Centro – São Carlos, Brazil)

Abstract


The use of cool materials on the building envelope is one of the most cost-effective ways to increase indoor thermal comfort conditions in hot climates and decrease the cooling energy needs. Despite the benefit of reducing cooling loads, researches have demonstrated that aging of roof coatings changes the initial solar reflectance (SR), which influences the long term building thermal and energy performance. Thus, this work presents preliminary natural weathering tests performed on samples of nine white coatings exposed to natural weathering for one year in the city of Sao Carlos, Brazil. Solar reflectances were measured with a spectrophotometer before and after exposure, every 3 months, for identifying the effect of aging along the time. The findings showed changes of 13% to 23% on SR after one year of natural weathering, with higher decrease on SR for rougher surfaces. The cleaning process restored from 90% to 100% of the original SR, which means maintenance can be an effective solution to restore the initial SR. Simulations indicated that roofs with higher solar reflectance increase indoor thermal comfort conditions and decrease the cooling energy need for buildings in hot climates, but the aging of white coatings increased the cooling energy needs along the time


Keywords


Roof solar reflectance;Aging;Natural weathering;Cleaning process;Thermal comfort;Energy savings;Tropical climate

Full Text:

PDF

References


[1]Kleerekoper, L.; Van Esch, M.; Salcedo, T.B. How to make a city climate-proof, addressing the urban heat island effect [J]. Resour. Conserv. Recycl., 2012, 64: 30-38. (http://dx.doi.org/10.1016/ j.resconrec.2011.06.004).

[2]Muscio, A. The solar reflectance index as a tool to forecast the heat released to the urban environment: potentiality and assessment issues [J] C l i m a t e , 2018, 6,12. (http://dx.doi.org/10.3390/cli6010012).

[3]Wang, C.; Wang, Z.; Kaloush, K. E. Critical review and gap analysis of impacts from pavements on urban heat island [R]. National Center of Excellence for Smart Innovations, Arizona State University. 2020. Final Report. (https://ncesmart.asu.edu/gapanalysis-of-impacts-from-pavements-on-uhi/).

[4]Synnefa, A.; Santamouris, M.; Akbari, H. Estimating the effect of using cool coatings on energy loads and thermal comfort in residential buildings in various climatic conditions [J]. Energy and Buildings, 2007, 39: 1167-1174. (https://doi.org/10.1016/ j.enbuild.2007.01.004).

[5]Jayasinghe, M. T. R.; Attalage, R. A.; Jayawardena, A. I. Roof orientation, roofing materials and roof surface colour: their influence on indoor thermal comfort in warm humid climates [J]. Energy for Sustainable Development, 2003, 7, n.1: 16-27 (https://doi. org/10.1016/S0973-0826(08)60345-2).

[6]Brazilian Standard. NBR 15220-3: Thermal performance in buildings - Brazilian bioclimatic zones and building guidelines for low-cost houses [S]. Rio de Janeiro: ABNT, 2005. (In Portuguese).

[7]Ramos, G. et al. Adaptive behaviour and air conditioning use in Brazilian residential buildings [J]. Building Research & Information, 2020. DOI:org/10.1080/09613218.2020.1804314.

[8]U n i t e d N a t i o n E n v i r o n m e n t P r o g r a m m e . Building and climate change: status, challenges and opportunities [R]. 2007. (http://hdl.handle. net/20.500.11822/7783).

[9]Empresa de Pesquisa Energética. Brazilian Energy Balance 2020: Year 2019 [R]. Rio de Janeiro: EPE, 2020. (https://www.epe.gov.br/sites-pt/publicacoesdados-abertos/publicacoes/PublicacoesArquivos/ publicacao-479/topico-528/BEN2020_sp.pdf).

[10]Jacob, D.; Kotova, L.; Teichmann, C.; Sobolowski, S.; Vautard, R.; Donnelly, C.; Koutroulis, A.; Grillakis, M.; Tsanis, I.; Damm, A.; Sakalli, A.; van Vliet, M. Climate impacts in Europe under +1.5◦C global warming [J]. Earth’s Future, 2018, 6: 264-285. DOI: 10.1002/2017EF000710

[11]Ascione, F. Energy conservation and renewable technologies for buildings to face the impact of the climate change and minimize the use of cooling [J], Solar Energy, 2017, 154, 15: 34-100. DOI:10.1016/j.solener.2017.01.022.

[12]Santamouris, M.; Synnefa, A.; Karlessi, T. Using advanced cool materials in the urban built environment to mitigate heat islands and improve thermal comfort conditions [J]. Solar Energy, 2011, 85: 3085-3102. (http://dx.doi.org/10.1016/j.solener.2010.12.023).

[13]Zinzi, M.; Agnoli, S. Cool and green roofs. An energy and comfort comparison between passive cooling and mitigation urban heat island techniques for residential buildings in the Mediterranean region [J]. Energy and Buildings, 2012, 55: 66-76. (http:// dx.doi.org/10.1016/j.enbuild.2011.09.024).

[14]Piselli, C.; Castaldo, V. L.; Pisello, A. L. How to enhance thermal energy storage effect of PCM in roofs with varying solar reflectance: Experimental and numerical assessment of a new roof system for passive cooling in different climate conditions [J]. Solar Energy, 2019, 192:106-119. (https://doi.org/10.1016/ j.solener.2018.06.047).

[15]Santamouris, M.; Synnefa, A; Kolokotsa, D; Dimitriou, V. Passive cooling of the built environment – use of innovative reflective materials to fight heat islands and decrease cooling needs [J] International Journal of Low-Carbon Technologies, 2008, 3, 2: 71- 82. (https://doi.org/10.1093/ijlct/3.2.71).

[16]Gentle, A. R.; Aguilar, J. L. C.; Smith, G. B. Optimized cool roofs: Integrating albedo and thermal emittance with R-value [J]. Sol. Energy Mater. Sol. Cells, 2011, 95, 12: 3207-3215. (https://doi. org/10.1016/j.solmat.2011.07.018).

[17]Paolini, R.; Zinzi, M.; Poli, T., Carnielo, E., Mainini, A. G. Effect of ageing on solar spectral reflectance of roofing membranes: Natural exposure in Roma and Milano and the impact on the energy needs of commercial buildings [J]. Energy and Buildings, 2014, 84:333-343. (http://dx.doi.org/10.1016/ j.enbuild.2014.08.008).

[18]Revel, G. M.; Martarelli, M.; Bengoche, M. A.; Gozalbo, A.; Orts, M. J.; Gaki, A.; Gregou, M.; Taxiarchou, M.; Bianchin, A.; Emiliani, M. Nanobased coatings with improved NIR reflecting properties for building envelope materials: development and natural aging effect measurement [J]. Cement Concrete Composites, 2013, 36: 128-135. (https://doi. org/10.1016/j.cemconcomp.2012.10.002).

[19]Tsoka, S.; Theodosiou, T.; Tsikaloudaki, K.; Flourentzou, F. Modeling performance of cool pavements and the effect of their aging on outdoor surface and air temperatures [J]. Sustainable Cities and Society, 2018, 42: 276-288. DOI:10.1016/j.scs.2018.07.016.

[20]Sleiman, M.; Ban-Weiss, G.; Gilbert, H. E.; Francois, D.; Berdahl, P.; Kirchstetter, T. W.; Destaillats, H.; Levinson, R. Soiling of building envelope surfaces and its effect on solar reflectance - Part I: Analysis of roofing product databases [J]. Solar Energy Materials and Solar Cells, 2011, 95, 12: 3385-3399. DOI:10.1016/j.solmat.2011.08.002.

[21]Sleiman, M.; Kirchstetter, T. W.; Berdahl, P.; Gilbert, H. E.; Quelen, S.; Marlot, L.; Preble, C. V.; Chen, S.; Montalbano, A.; Rosseler, O. Soiling of building envelope surfaces and its effect on solar reflectancePart II: Development of an accelerated aging method for roofing materials [J]. Solar Energy Materials and Solar Cells, 2014, 122: 271–281. DOI:10.1016/j.solmat.2013.11.028.

[22]Sleiman, M.; Chen, S.; Gilbert, H. E.; Kirchstetter, T. W.; Berdahl, P.; Bibian, E.; Bruckman, L. S.; Cremona, D.; French, R. H.; Gordon, D. A. Soiling of building envelope surfaces and its effect on solar reflectance– Part III: Interlaboratory study of an accelerated aging method for roofing materials [J]. Solar Energy Materials and Solar Cells, 2015, 143: 581-590. DOI:10.1016/j.solmat.2011.08.002.

[23]Ferrari, C.; Santunione, G.; Libbra, A.; Muscio, A.; Sgarbi, E. How accelerated biological aging can affect solar reflective polymeric based building materials [J]. Journal of Physics: Conference Series, 2017, 923. DOI:10.1088/1742-6596/923/1/012046.

[24]Akbari, H.; Berhe, A. A.; Levinson, R.; Graveline,S.; Foley, K. Aging and weathering of cool roofing membranes [R]. Report LBNL-58055. Berkeley: Lawrence Berkeley National Laboratory, 2005.

[25]Bretz, S.; Akbari, H. Long-term performance of highalbedo roof coatings [J]. Energy and Buildings, 1997, 25, 2: 159-167. (https://doi.org/10.1016/S0378- 7788(96)01005-5).

[26]Levinson, R.; Berdahl, P.; Berhe, A.; Akbari. H. Effect of soiling and cleaning on reflectance and solar heat gain of a light-colored roofing membrane [J]. Atmospheric Environment, 2005, 39: 7807-7824. DOI:10.1016/j.atmosenv.2005.08.037.

[27]Alchapar, N.; Correa, E. Aging of roof coatings solar reflectance stability according to their morphological characteristics [J]. Construction and Building Materials, 2016, 102: 297-305. DOI:10.1016/j.conbuildmat.2015.11.005.

[28]Ferrari, C.; Touchaei, G. A.; Sleiman, M.; Libbra, A.; Muscio, A.; Siligardi, C.; Akbari, H. Effect of aging processes on solar reflectivity of clay roof tiles [J]. Advances in Building Energy Research, 2014, 8, 1: 28-40. DOI:10.1080/17512549.2014.890535.

[29]De Masi, R. F.; Ruggiero, S.; Vanoli; G. P. Acrylic white paint of industrial sector for cool roofing application: Experimental investigation of summer behavior and aging problem under Mediterranean climate [J]. Solar Energy, 2018, 169: 468–487. DOI:10.1016/j.solener.2018.05.021.

[30]Dornelles, K. A.; Caram, R. M.; Sichieri, E. Natural Weathering of Cool Coatings and its Effect on Solar Reflectance of Roof Surfaces [J]. Energy Procedia, 2015, 78: 1587-1592. (https://doi.org/10.1016/ j.egypro.2015.11.216).

[31]Mastrapostoli, E.; Santamouris, M.; Kolokotsa, D.; Vassilis, P.; Venieri, D.; Gompakis, K. On the ageing of cool roofs: Measure of the optical degradation, chemical and biological analysis and assessment of the energy impact [J]. Energy and Buildings, 2016, 114: 191-199. DOI:doi.org/10.1016/j.enbuild.2015.05.030.

[32]Aoyama, T.; Sonoda, T.; Nakanishi, Y.; Tanabe, J.; Take-bayashi, H. Study on aging of solar reflectance of the self-cleaning high reflectance coating [J]. Energy and Buildings, 2017, 157: 92-100. DOI:10.1016/j.enbuild.2017.02.021.

[33]Paolini, R.; Zani, A.; Poli, T.; Antretter, F.; Zinzi, M. Natural aging of cool walls: Impact on solar reflectance, sensitivity to thermal shocks and building energy needs [J]. Energy and Buildings 153 (2017) 287–296. (http://dx.doi.org/10.1016/ j.enbuild.2017.08.017).

[34]ASTM. ASTM E903-96: standard test method for solar absorptance, reflectance, and transmittance of materials using integrating spheres [S]. ASTM International, 1996.

[35]ASTM. ASTM G173-03: standard tables for reference solar spectral irradiances – direct normal and hemispherical on 37° tilted surface [S]. ASTM International, 2003.

[36]ASTM. ASTM C1371-15. Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers [S]. ASTM International, 2015.

[37]U.S. Department of Energy’s (DOE) Building Technologies Office (BTO). EnergyPlus – Weather Data [R]. (https://energyplus.net/weather).

[38]Brazilian Standard. NBR 15575: Residential buildings: performance [S]. Rio de Janeiro: ABNT, 2013. (In Portuguese).

[39]Coelho, T. C. C.; Gomes, C. E. M.; Dornelles, K. A. Thermal performance and solar absorptance of asbestos free fibercement roof tiles under different natural aging processes [J]. Ambiente Construído, 2017, 17, 1: 147-161. (dx.doi.org/10.1590/s1678- 86212017000100129)

[40]ASHRAE 55: thermal environmental conditions for human occupancy [S]. ASHRAE. Atlanta, 2017.

[41]Szokolay, S. V. Introdução à ciência arquitetônica: a base do projeto sustentável [M]. 2019. Perspectiva, São Paulo. (in Portuguese).

[42]S e k e r, D . Z . ; Ta v i l , A . Ü . E v a l u a t i o n o f exterior building surface roughness degrees by photogrammetric methods [J]. Building and Environment, 1996, 31, 4.

[43]Pisello, A. L.; Rossi, F.; Santamouris, M.; Synnefa, A.; Wong, N.; Zinzi, M. Local climate change and urban heat island mitigation techniques - the state of the art [J]. Journal of Civil Engineering and Management, 2016, 22: 1-16. DOI:10.3846/13923730.2015.1111934.

[44]Rosado, P.; Levinson, R. Potential benefits of cool walls on residential and commercial buildings across California and The United States: Conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants [J]. Energy and Buildings, 2019, 199: 588-607. DOI:10.1016/j.enbuild.2019.02.028.

[45]Cool Roof Rating Council Portland, 2021. (https:// coolroofs.org/).



DOI: https://doi.org/10.30564/jaeser.v4i2.2812

Refbacks

  • There are currently no refbacks.
Copyright © 2021 Kelen Almeida Dornelles Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.