Wednesday, June 3, 2009

Electric Bill Draining Your Pocketbook? Paint Your Roof White and Save $ and the Earth.

On a summer day go outside and feel the difference between the searing heat of an asphalt parking lot compared with the strikingly cooler light colored sidewalk. This same phenomena happens on millions of rooftops nationwide causing hot houses, high cooling bills, and contributing to the heat island effect where urban areas are several degrees hotter than surrounding natural areas.

Energy Secretary and Nobel Prize winning physicist Steven Chu recently described perhaps the simplest, most effective way to reduce your home energy bills, converting your existing roof to reflective materials. Author Sam Kornell reports on a study by three leading energy experts showing that if the average American converted 2000 sqft of roof from black shingles to white, the reflected sunlight and heat from the albedo effect would offset the equivalent of 20 tons of carbon emissions under current technology. 20 tons of carbon happens to be the average American's output as well.

Air conditioning load belongs to a small class of serious strains on both the current grid as well as driving a disproportionate share of rising energy costs. The Florida Solar Center studied the impact of roof conversion on a set of typical residential homes in Ft Meyers Florida. Controlling for all other factors they found conversion of roofing to reflective materials reduced home cooling energy consumption up to 26% and peak demand overall by roughly 1/3rd. That's right, just simply changing roof color will cut your energy bill by 1/4 and avoid the need for 1/3 of new energy development.

The EPA and Department of Energy provide an online calculator anyone can use to find the potential energy and money savings available by converting their own roof to reflective materials. After entering some details about the building type, heating and cooling equipment, location, and local electric rates the calculator returns an estimate of yearly energy and cost savings. You can find your local electric rates here and gas price here. Check it out and report back your findings!

Builders and manufactures are quickly catching on to this simple, cheap and effective tool for combating climate change. Roofing company Petersen-Dean markets a new roof covering that is both reflective and integrates solar panels into the material. They estimate their SmarterRoof to be less expensive and last 40% longer than traditional roofing, offset up to 90% of your energy bills, and will repay for itself in 5 - 7 years. This double punch of cooling and electricity supply instead coating your roof with asphalt shingles empowers homeowners to take charge of their energy usage.

Some folks argue that the "winter penalty," or winter time heat gain lost by converting from black roofs offsets some energy savings from reduced summer cooling load. However, construction giant McGraw Hill explains that researchers studied 11 cities across the country and found that in while actual levels vary between homes in northern and southern sections of the country, in all instances the minimal loss of winter heating is outweighed by the savings in summer cooling. In northern climates any winter heat gain is minimal due to the low angle of sunlight, shorter daylight hours, fewer sunny days, and in the coldest climates snow covered roofs.

So what's stopping this cheap, effective method to reduce energy bills and our impact on the earth? Silly architectural and aesthetic community regulations and city ordinances that mandate dark roofing materials in order to reduce the glare of reflective light. A simple google search for "community CCR's and roof material" returns a wide variety of subdivisions, planned communities, and other organizations around the country that prohibit homeowners from choosing to change their roof color. These aesthetic regulations effectively require homeowners to pay higher energy bills and prohibit them from taking cost effective measures to reduce their personal energy consumption. For those of you who live under CC&R's, get a seat on the architectural review committee, or whatever your local review board is named, and advocate for dropping silly and wasteful aesthetic regulations that prohibit personal choice, sound economics, and good environmental practice. For others, make sure your state makes reflective roofing part of their building codes as California, among others, has done. For more information on cool roofs and building codes nationwide see this review by Dr.'s Akbari and Levinson.

The bottom line: Converting roof materials to reflective colors has the potential to offset a massive portion of the annual human contribution to global heat gain. Beyond drastically reducing summer cooling bills cool roof materials are less expensive and more durable than traditional materials. But until communities and cities drop restrictive aesthetic regulations some public citizens are excluded from this simple, cheap, and effective method to make our world a better place while saving their hard earned dollars.

The full original study: Global cooling: increasing world-wide urban albedos to offset CO2 by Hashem Akbari · Surabi Menon · Arthur Rosenfeld


  1. Nice Blog! Well most of your content is original and informative. Here is another Site which, too, is nice in my opinion Electric Bills, Lights Led, Save Energy

  2. Hmm, if painting the house white will pull your electrical bills down, then it should be given a try. After all, it's a Nobel Prize-winning physicist who said it. It's definitely worth a try.

    -> Sierra Nordgren


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