Roof Links

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* The albedo of an object is the extent to which it diffusely reflects light from sources such as the Sun. The albedo of fresh snow is 0.9 and that of fresh asphalt is 0.04

* Studies show that white roofs reduce air-conditioning costs by 20 percent or more in hot, sunny weather.

* How shiny is LA? The California South Coast Air Basin’s urban albedo is higher than its suburban albedo because the suburban land use has more vegetation. LBL did a fly-over to take measurements.

* Planted “green” roofs provide insulative value. They do not, however, have the reflectivity provided by white roofing materials, which reduce direct solar heat gain. When seeking highest efficiency per capital investment, the choice between a green roof and a white, reflective one requires study of alternative insulation schemes; climate is a major factor.

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Roofs in snow, Brett Weston

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