Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials
Title | Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials |
Publication Type | Journal Article |
Year of Publication | 2007 |
Authors | Ronnen M Levinson, Paul H Berdahl, Hashem Akbari, William A Miller, Ingo Joedicke, Joseph C Reilly, Yoshi Suzuki, Michelle Vondran |
Journal | Solar Energy Materials and Solar Cells |
Volume | 91 |
Start Page | 304 |
Issue | 4 |
Pagination | 304-314 |
Date Published | 02/2007 |
Keywords | absorption, asphalt shingle, clay tile, coating, concrete tile, conversion coating, Heat Island, metal, Methods & Protocols, near infrared, pigment, reflective, residential, roofing, scattering, Solar, treatment, wood |
Abstract | We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7-2.5 μm) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat. |
DOI | 10.1016/j.solmat.2006.06.062 |