How Cool is Your Roof?
A solution for saving money and preventing global warming
Rooftop growth: Architect Hari Sripadanna’s home in Saratoga sports the ultimate cool roof with living gardens on its flat, south-facing sections.
Photograph by Lane Johnson
Simple modifications made to your roof can pay big dividends in lowering your energy bill. During the summer months, the temperature of a conventional roof can rise to 180 degrees or more, transferring heat to the living quarters below. Change your old roof to a “cool roof” and it will reflect the sun’s heat instead of overheating your home.
Approximately 90 percent of the roofs in the United States are black, brown, or other dark colors, and these colors absorb heat instead of reflecting it. According to architect Hari Sripadanna of Srusti Architects in Saratoga, “Changing the color of the roof is one of the simplest things one can do to reduce heat gain, because it requires very little intrusive remodeling.”
One of the easiest and least expensive ways to cool off your existing roof is simply to paint it white. Throughout history, buildings in hot climates around the world have been whitewashed to take advantage of the cooling effect of light, reflective colors. According to the Bay Area Cool Roofs Project, asphalt tile, composite, and gravel roofs can all be painted. The most effective roof paints, available under the brand names Henry or Hyperseal, contain tiny aluminum particles to enhance reflectivity. You can hire a painting or roofing contractor to paint your roof, or ambitious homeowners can do the job themselves.
A more costly approach, best undertaken when it’s time to replace your old roof, is to re-roof with solar-reflective shingles, tiles, or coatings, which are available in a wide range of colors and styles. The Cool Roofs Rating Council (CRRC), an EPA-recognized certification body for the Energy Star program, says that as long as the roofing product has a high solar reflectance, it will cool your roof no matter what color it is. The CRRC maintains a database of roofing products rated for solar reflectance at www.coolroofs.org.
Replacing your old roof with solar-reflective materials is not only good for your air-conditioning bills, it’s also good for the planet. Since taking office in January 2009, U.S. Energy Secretary Steven Chu has been touting the benefits of cool roofs, stating that switching over to cooler roofs would greatly reduce our country’s CO2 emissions.
Architect Sripadanna has taken the cool roof concept even further. His home has a “living roof” made of panels of self-sustaining plants, which protect the roof, insulate the house, and even produce oxygen to clean the air. Living roofs are a luxury item for most homeowners, but in recent years their cost has dropped from about $15 per square foot to $8 to $10 per square foot. “If you already have some kind of membrane barrier, living roofs are simple to install, aesthetically pleasing, and maintenance-free,” Sripadanna says.
Bay Area Companies That Install Cool Roofs
Dura-Foam Roofing, Menlo Park
Platinum Roofing, San Jose
Dinyari Incorporated, San Jose
Acme Roofing Company, San Francisco
Abril Roofing Company, Concord
Blue Turtle Roofing, San Rafael