A recent episode of This Old House, an American TV series that highlights do-it-yourself home improvement tasks, examined the properties of Solar Reflective Asphalt Shingles. Part of the qualification for these shingles included a QUV accelerated weathering test to ensure the reflective properties are maintained.
Asphalt shingles, the most prevalent residential roofing material in the US, are made of small rock-like granules pressed on an asphalt-fiberglass substrate, and have a dark-colored appearance. For houses in more southern climates, the high solar absorption of the dark surface (only about 8% reflectivity) can lead to added energy costs. Nevertheless, dark-colored shingles are more aesthetically pleasing to majority of homeowners, who end up living with higher energy bills. Saint Gobain, a manufacturer of such shingles, has developed proprietary coatings and granules that retain that dark appearance, but are effective in reflecting much of the infrared light that is contributing to higher temperatures. The premium shingles can achieve as high as 40% reflectivity, and therefore, less energy is consumed by the cooling system to maintain temperatures within the building.
The QUV tester is featured through 5:45-7:33 of the video, where a representative from Saint Gobain details the weathering simulation and accelerated testing. The representative does a great job of detailing the exposure and how each cycle best represents outdoor conditions. Short videos from within the chamber is even included, with the host of the show saying ‘Wow! Look at the blue light!’ (Note: do not look directly at UVA light!).
The entire video is worth watching, as it provides good context on how reflective surfaces and cool roofing ideas can provide lower energy costs, but also the consideration that these products need to retain the properties for their expected lifetime after several years of exposure to weathering.