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White Roofs Better Than Dark, Vegetated Roofs, LBNL Study Finds

BERKELEY, Calif.—Compared to traditional dark-colored roofs and green or “vegetated” roofs, white roofs offer greater ability to lower temperatures that lead to the urban heat island effect, and they do it at less cost, according to a recent report. The Lawrence Berkeley National Laboratory report states that building owners “concerned with global warming should choose white roofs, which are three times more effective than green roofs at cooling the globe.” The authors analyzed 22 commercial flat roof projects in the U.S. and performed a 50-year life-cycle cost analysis. They assumed a 20-year service life for black roofs and white roofs, and 40 years for green roofs. Compared to black roofs, the report says, white roofs save $25/m2 ($2.30/ft2) and green roofs have an additional cost of $71/m2 ($6.60/ft2). The authors also concluded that black roofs should be prohibited in some areas. “We strongly recommend building code policies that phase out dark-colored roofs in warm climates to protect against their adverse public health externalities,” the report states.



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