Dark-Colored Metal Roofs That Reflect Like Light Colors

PPG Coil and Extrusion Coatings has released a variant of its Duranar® coatings for metal roofs that contains special pigments to reduce solar gain. With these new “Duranar SPF” coatings, 98% of PPG’s standard colors meet the EPA Energy Star steep-roof threshold of 25% total solar reflectivity, whereas with standard Duranar coatings about half of the medium and dark colors do not meet the threshold.

Increased reflectivity is achieved by using pigments that are highly reflective in the nonvisible, infrared portion of the solar spectrum. The use of “SPF” in the product name is a reference to the sun-protection factor ratings for sunscreen. Interestingly, the reflective pigments affect some colors’ ratings dramatically, others more modestly, and in some colors they do not affect reflectivity at all. These pigments do not affect the surface emissivity of the coating—as with standard Duranar pigments, only certain colors meet the minimum 0.9 emissivity required by the LEED™ rating system’s cool roofs credit.

– NM