White Roofs Have Unexpected Impacts

A study by Arizona State University shows that white roofs can deflect sunlight into the atmosphere, changing cloud cover and reducing rain

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By Craig A. Tyler

Philly.com

Five years ago, Philadelphia City Council passed a green building code requiring that white roofs be used on certain buildings because they are more energy-efficient and help reduce air pollution.

New York and Chicago have similar codes. But the white-roof craze is based on old and faulty research that has promulgated two myths - that these roofs save energy atop any building and that they decrease global warming.

Philadelphians should be concerned that the city is wasting money on energy and possibly causing more, not less, global warming.

There is a significant heating penalty associated with using white roofs in central and northern climates, where owners use three to five times as much energy to heat their buildings than to cool them. In cities like Philly, white roofs consume more energy, which means they cause more cardon dioxide emissions.

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