Summer is when new roofs are installed and old ones are redone, but contrary to news articles and experts touting the benefits of white reflective roofs, the fact is that my home city of Seattle and most northern cities in the U.S. waste millions in energy costs and precious natural resources by buying into the myth that white roofs are energy efficient regardless of climate zone.
White roofs have been migrating north for the past 10 years. There are mandates for their use in Chicago, New York and Philadelphia. I work for the leading manufacturer of both white and darker colored roofs, and we know that white roofs reduce cooling costs, which are beneficial in warmer, southern climates, but we also know the untold story is that they carry a significant heating penalty in cities like Seattle, where heating is utilized far more than cooling.
Those with a vested interest in white roofing have capitalized on perceptions created by the Department of Energy's ENERGY STAR program and incomplete studies from sources such as Lawrence Berkeley National Laboratory, and they have been able to launch a movement that not only is costly but also damaging to our environment.
Using a roof energy savings calculator developed by Oak Ridge National Laboratory and approved by Lawrence Berkeley, the EPA, DOE and California Energy Commission, I found that regardless of heat source, square footage or insulation level, reflective white residential roofs in Seattle waste natural resources and cost homeowners more money.
The same is true with Seattle's commercial buildings. A relatively small 10,000-square-foot building with a white roof and an insulation level of R-20 would have an average cooling benefit of $61, but would have an average heating penalty of $498, for a net energy cost loss of $437 per year.
My home city is not alone. Dozens of northern cities that would get similar results using this roof energy savings calculator.
Proponents also claim that white roofs reduce global warming. But a study at Stanford University shows that white roofs may actually INCREASE, not decrease, the earth's temperature. The study suggests that white roofs reflect heat upward into the atmosphere where it mixes with black and brown soot particles that retain heat and contribute to global warming. Another study from Arizona State University indicates widespread adoption of highly reflective cool roofs could negatively impact rainfall patterns across the United States.
Those northern cities that have adopted white roofing mandates, as well-intentioned as they may be, are beginning to get a black eye. Design professionals, roof consultants, contractors, facility managers and building scientists are getting increasingly concerned with mandates that limit their ability to choose the most energy-efficient roofing materials. They know it is a far more complex issue than just the roof's color.
The good news is that there is a growing resentment regarding these top-down, one-size-fits-all government mandates. The EPA is on record urging us to remember that "the energy savings that can be achieved with white reflective roofing is highly dependent on facility design, insulation used, climatic conditions, building location, and building envelope efficiency."
In the past year, three different national regulatory bodies voted down proposals to specify white reflective roofs in northern areas of the United States. And in my region, recent building guides in the Pacific Northwest show that white roof installation is not recommended to improve energy efficiency when retrofitting a roof.
So we are starting to expose the myth, but we must continue to research the issue and seek the facts to find balance and counter a movement that has built momentum over the last decade -- and cost Seattle and other American cities untold dollars in unnecessary energy costs.