Know What's Cool in L.A.? Roofs

A new amendment to Los Angeles' building codes now requires all new residential roofs to reflect more sunlight, a move that should help the city reduce the effects of global warming.

The amendment to the city's Municipal Building Code passed unanimously Wednesday by the Los Angeles City Council and will require all new or rebuilt roofs to use so-called "cool roof" material, which reduces the amount of solar energy the roof absorbs -- helping reduce both heat inside the home and the so called "urban heat island" effect.

Cool roofs can be as much as 50°F cooler on warm days than their traditional black-shingled counterparts, and they can lower temperatures inside the building by several degrees as well.

Jonathan Parfrey, Executive Director of the group Climate Resolve, called the new building code amendment "a great step forward in meeting the City's energy efficiency and climate goal." Parfrey's group had worked with the City Council to craft the mandate. "Cool roofs are a great way for Angelenos to keep their energy costs low and significantly reduce Green House Gas emissions in the City," Parfrey added.

As ReWire explained earlier this year, a homeowner's choice of roofing material can have a significant impact on how much energy -- and money -- it takes to keep a building cool during the summer. As the number of days with temperatures above 95° is expected to rise dramatically in the Los Angeles area, that's going to become far more important.

The Los Angeles Department of Water and Power, by the way, is expanding its incentive program for cool roofs to offset any additional costs the City Council's move will have on homeowners. Current rebates for cool roof materials run between twenty and thirty cents per square foot.