Technology Snapshot & Benefits:
Energy-efficient roofing materials such as reflective coatings were once a concern only in warm climates. In a Professional Roofing magazine article, National Coatings Corporation Technical Director William A. Kirn writes, "Reflective coatings now are used throughout the U.S. Continued emphasis on political, environmental and energy-related issues likely will further drive interest in, and more important, use of reflective roof coatings." (Read the entire article from the Nov. 2008 issue here.) According to the California Energy Commission, scientists have known for centuries that putting white roofs on homes and buildings is a way to reflect the sun's powerful rays. Similarly, cool-colored pavements aid in the reduction of "urban heat islands." Could this pave the way for cooling our globe?

In September 2008, California Energy Commissioner Art Rosenfeld and Lawrence Berkeley National Laboratory scientists Hashem Akbari and Surabi Menon proposed "an international campaign to organize 100 of the world's largest cities in tropical and temperate zones to develop programs to require white roofs and 'cool pavements' when roofs are initially constructed and pavements installed." They believe this simple and effective idea, including white roofs, can save energy, improve air quality, and "cool the globe." Additionally, "city leaders and urban planners quantify the amount of CO2 they can offset."

Estimated Cost Savings:
ENERGY STAR^® states that "one-sixth of all electricity consumed in the U.S. is used to cool buildings (http://www.energystar.gov/index.cfm?c=roof_prods.pr_roof_products)." Using ENERGY STAR^® roofing products can lower roof surface temperature dramatically, thereby decreasing the amount of heat transferred to the building's interior. This can reduce the air conditioning required to cool the home or building which, ENERGY STAR^® claims, leads to reducing energy bills by up to 50 percent. This is especially true of energy bills from sunny, hot climates. The California Energy Commission concludes that "reflective roofs can reduce a building's energy use by 20 percent and potentially save the U.S. in excess of $1 billion in annual energy savings." (Read about scientists for "global cooling" via white roofs and cool pavements here.)

Issues:
Normal wear and tear causes some degradation of roof reflectivity which, according to ENERGY STAR^®, is to be expected within the first few years after installation. More dirt and debris accumulates on flat roofs because their slope is not great enough to allow washing by rain. ENERGY STAR^® recommends consulting your roofing contractor and learning, and in turn following, manufacturer's maintenance procedures and suggestions to maximize energy savings.

Regional Issues:
Since 2005, commercial buildings with flat roofs in California have been required to have white roofs. Residential sloped roofs are also becoming more efficient. Beginning in August 2009, California legislation (Title 24) will require "new residential roofs and retrofit constructions in California to have 'cool-colored' roofs which reflect a higher fraction of the sun's rays than current roofing materials of the same color. (Read their 2008 Building Energy Efficiency Standards here.)

Installation:
ENERGY STAR^® labels appear on the roof product's label or advertisement if efficiency requirements are met. ENERGY STAR^® recommends consulting a roofing contractor or product manufacturer regarding installation.

For more information on this topic:

The California Energy Commission

Lawrence Berkeley National Laboratory Heat Island Group
Research Highlights (11/10/08): "White Roofs Cool the World, Directly Offset CO2 and Delay Global Warming"

California Energy Commission, Arthur H. Rosenfeld, Commissioner
"Energy Efficiency: The First and Most Profitable Way to Delay Climate Change" Moro Camp (7/12/08)

ENERGY STAR® for Roof Products

ENERGY STAR® Qualified Roof Product Manufacturers

Professional Roofing Magazine
"Coating Opportunities" (11/2008)