Does Reducing the ‘Urban Heat-Island Effect’ Help Renewable Energy?

The world has to adopt a cost for emissions. Could you address changes that help us reduce energy absorption of sunrays? I am thinking of white roof and walls on buildings. White coated asphalt or concrete roads. Reflective cars like white colored. This, like solar and wind energy, is a very small step but a step still in the right direction. –Thomas S., Rockford, IL

Thomas, I can’t agree with you more — there are no silver bullets addressing the nexus of energy and pollution/greenhouse gas emissions — but rather adopting a portfolio of lower energy and emission strategies is the answer. A 1999 article authored by Lawrence Berkley Lab experts (Rosenfeld, Romm. Akbari and Lloyd) [link below] concluded that reducing urban heat-island effects will cut ozone by 12% (thereby reducing urban smog), sequester significant amounts of atmospheric carbon, and save the residents of a large city upwards of $500 million dollars by planting trees, using white-colored roofing, and lighter-colored pavement. Author James Cascio in his article “Green and White” states: “One sixth of the electricity consumed in the United States goes to cool buildings, at an annual power cost of $40 billion. Moreover, a 5 degree F heat island greatly raises the rate at which pollutants-nitrogen oxides and volatile organic compounds emanating from cars and smokestacks — “cook” into ozone, a highly oxidizing and irritating gas that is the main ingredient of smog. In Los Angeles, for example, ozone rises from an acceptable concentration at 70 degree F to unacceptable at 90 degree F. The Los Angeles heat island raises ozone levels 10-15 percent and contributes to millions of dollars in medical expenses.” While many promote light color roofs, another set of advocates (including Mayor Daley of Chicago) promote Green Roofs. According to the New York city-based nonprofit EPF Green Roofs [link below]: “Green roofs provide important environmental and human health benefits including ameliorating the urban heat island effect, lowering energy expenditures, purifying the air, and reducing storm-water runoff. On summer days, cities can be up to seven degrees warmer than surrounding areas, becoming incubators for smog, threatening public health, and creating a greater energy demand, a problem known as urban heat-island effect. By replacing the heat-absorbing tar and other dark roofing materials with plants and grasses, green roofs can substantially mitigate the urban heat-island effect. Storm-water runoff, which carries contaminants, including dangerous heavy metals, from paved surfaces and rooftops to our natural waterways, has been identified as a major source of water pollution. Green roofs can reduce these negative effects by absorbing up to 75% of rain that falls upon them.” The same can be said for vehicles. Lighter colors would allow manufacturers to install smaller air-conditioners, which, in turn, would increase fuel mileage. Some auto companies install sunroofs tinted with photovoltaic material, which powers a vent fan, so they can reduce air-conditioner sizes (installed to reduce heat faster in the first minutes you enter and start your vehicle) also increasing vehicle mileage. So again, personal actions in buildings, land cover, and vehicles can save energy, pollution and enhance water quality and health — all in one investment. Renewable energy, in order to be cost effective, is more viable with reduced loads — and reducing heat loads both for air-conditioning (thermal) or electricity is part of that. We have to look at this all as a “system.” — Scott Sklar Scott Sklar is President of The Stella Group in Washington, DC, a distributed energy marketing and policy firm. Scott, co-author of “A Consumer Guide to Solar Energy,” uses solar technologies for heating and power at his home in Virginia.