Influence of dirt and coating deterioration on the aging of solar reflectance of high-reflectance paint

Taizo Aoyama; Takeshi Sonoda; Hideki Takebayashi; Taizo Aoyama; Takeshi Sonoda; Hideki Takebayashi

doi:10.3934/matersci.2019.6.997

AIMS Materials Science

2019, Volume 6, Issue 6: 997-1009. doi: 10.3934/matersci.2019.6.997

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Influence of dirt and coating deterioration on the aging of solar reflectance of high-reflectance paint

1.
KANEKA CORPORATION, 1-8, Miyamae-cho, Takasago-cho, Takasago Hyogo 676-8688, Japan
2.
Department of Architecture, Graduate School of Engineering, Kobe University, Kobe Hyogo 657-8501, Japan

Received: 29 July 2019 Accepted: 10 September 2019 Published: 22 October 2019

Cool-roof coatings have received considerable attention worldwide as a solution for the “heat island” effect in urban areas. The solar reflectance of roofs coated with high-reflectance paint is reduced by dirt. We continuously measured the solar reflectance of a roof coated with high-reflectance paint with and without a self-cleaning function for more than two years. The solar reflectance of self-cleaning paint decreased by 0.5% per month over two years, due to the effect of dirt. The solar reflectance of conventional paint decreased by 4% per month over four months after coating and then reached a value similar to that for the self-cleaning paint for two years due to deterioration. With a slight decrease in solar reflectance, the self-cleaning function is effective in mitigating the heat island effect and obtaining continuous energy-savings. We applied the alkyl silicate system as self-cleaning for high-reflectance paint, the solar reflectance was measured continuously at 1 minute intervals, and the actual state of the fluctuation in reflectance over the short and long terms was analyzed with the influence of the altitude of the sun. The deterioration of the coating was also investigated by gloss retention and chalking test.
- high-reflectance paint,
- solar reflectance,
- heat island effect,
- aging,
- self-cleaning,
- dirt,
- deterioration
Citation: Taizo Aoyama, Takeshi Sonoda, Hideki Takebayashi. Influence of dirt and coating deterioration on the aging of solar reflectance of high-reflectance paint[J]. AIMS Materials Science, 2019, 6(6): 997-1009. doi: 10.3934/matersci.2019.6.997

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Abstract

Cool-roof coatings have received considerable attention worldwide as a solution for the “heat island” effect in urban areas. The solar reflectance of roofs coated with high-reflectance paint is reduced by dirt. We continuously measured the solar reflectance of a roof coated with high-reflectance paint with and without a self-cleaning function for more than two years. The solar reflectance of self-cleaning paint decreased by 0.5% per month over two years, due to the effect of dirt. The solar reflectance of conventional paint decreased by 4% per month over four months after coating and then reached a value similar to that for the self-cleaning paint for two years due to deterioration. With a slight decrease in solar reflectance, the self-cleaning function is effective in mitigating the heat island effect and obtaining continuous energy-savings. We applied the alkyl silicate system as self-cleaning for high-reflectance paint, the solar reflectance was measured continuously at 1 minute intervals, and the actual state of the fluctuation in reflectance over the short and long terms was analyzed with the influence of the altitude of the sun. The deterioration of the coating was also investigated by gloss retention and chalking test.

References

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