White or reflective roofs typically

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When light touches any surface, some of its energy is reflected and some absorbed. Individual colors are how the brain perceives the wavelength of the reflected light. White light contains all the wavelengths of the visible spectrum, so when the color white is reflected, all wavelengths are also reflected, making it the most reflective hue.

In the 1980s, the U.S. Department of Energy (DOE) began researching the benefits of reflective roofing in urban environments with the goal of reducing high temperatures caused by dark roofing, asphalt roads, and other heat-absorbing building materials (known as the ‘heat island effect’). They found only increase 6 to 14 C (10 to 25 F) above ambient air temperatures during the whatsapp number database day, which translates up to 15 percent savings on air-conditioning use over the course of a year for a typical one-story residence.

In 1998, the Cool Roof Rating Council (CRRC) was established to develop credible and universal methods to evaluate and classify the solar reflectance and radiative properties of roofing products, and share that information publically. “Coolness,” as defined by CRRC, is measured by two properties:

solar reflectance (the fraction of solar energy reflected by the roof); and
thermal emittance (the relative ability of the roof surface to radiate absorbed heat.