Los Angeles, the second most populous city in the U.S., has made history by becoming the first major city to require all new and refurbished homes have a “cool roof.” On December 17, 2013 the Los Angeles City Council unanimously passed an update to its Municipal Building Code. A cool roof is one that “reflects and emits the sun’s heat back to the sky instead of transferring it to the building below,” according to the Cool Roof Rating Council.
Cool roofs are great in an area like Los Angeles which has warm summers and mild winters. A white roof is one of the most popular choices for a cool roof, and the Lawrence Berkeley National Laboratory’s Heat Island Group estimates that a white roof can reflect 80 percent of sunlight in the summer, making the building cooler. A cooler building in the summer means less air conditioning is used and that saves homeowners money. Cool roofs offer other benefits, according to both Climate Resolve, which worked on the ordinance with the City Council, and the Cool Roof Rating Council. Those other benefits include improving air quality by reducing the formation of ozone, reducing greenhouse gas emissions, and decrease roof maintenance costs.
“Climate Resolve has been working on this ordinance because we know it is a great step forward in meeting the City’s energy efficiency and climate goals. Cool roofs are a great way for Angelenos to keep their energy costs low and significantly reduce greenhouse gas emissions in the City,” said Jonathan Parfrey, Executive Director of Climate Resolve. “Cool roofs are a win-win-win for the people of Los Angeles,” Parfrey added. “Keeping temperatures down on Extreme Heat Days will protect lives; energy efficiency will save millions of dollars; and cool roofs will help Los Angeles combat global climate change at the local level.”
A UCLA report released in 2011 found that Los Angeles residents could save up to $30 million a year if the city adopted cool roofs. As the report’s author, Cara Horowitz, the Andrew Sabin Family Foundation Executive Director of the Emmett Center, put it, “A switch to cool roofs in Los Angeles would provide a climate change benefit, cooling the atmosphere enough to offset the warming caused by nearly 40 million metric tons of emitted CO2, in some scenarios.” That equals about 80 percent of the greenhouse gas emissions by Los Angeles in a year, or the emissions of about seven million cars on the road for a year.
Photo: Idaho National Laboratory