Ronnen Levinson a,n, Hashem Akbari a,1, Paul Berdahl a, Kurt Wood b, Wayne Skilton b, Jerry Petersheim b
2 paint layers for concrete til and asphalt shingles.
Each layer aqueous polyvinylidene fluoride (PVDF)/acrylic technology.
First layer white basecoat with weak absoroption and strong backscattering from 500 to 2000nm.
2nd layer color topcoat with weak NIR absorption and strong NIR backscattering.
Backscattering reverses the direction of the light and absorption converts light to heat.
45% of sunlight arrives in the visible spectrum.
Performance is evaluated based on how high S is for a given value of L or how low L is for given value of S.
S= solar reflectance
L=CIELAB tristimulus value of L* (lightness)
California offers rebates for installing reflective roofing. Steep sloped roofs must have a reflectance of .25 for a .10 ft^2 rebate. .40 is tier 2 rebate of .20/ft^2.
Rough surfaces are less reflective than smooth ones as part of the reflected light returns to the rough surface.