White Roofs Help The Environment

White is an excellent choice, especially when deciding on a car color or your roof color.

Maria-José Viñas / American Geophysical Union

A recent study showed that having white and other light-colored roof surfaces in urban areas equates to taking millions of cars of the road by preventing tons upon tons of CO2 output and reducing your carbon footprint.

Readers of Green Blizzard were asking how do white roofs help the environment?

White, or light-color roofs reflect or re-emit sunlight instead of absorbing it and therefore lower the demand for A/C in warmer months.  When a building’s roof and structure are not retaining as much heat,  it requires less air conditioning.  This saves you money in energy costs, it uses less non-renewable resources like coal and natural gas, and it reduces the carbon footprint.   The results are dependent on your latitude.  Scientists point out that extra heating costs can outweigh air-conditioning savings in places like Minneapolis or Detroit.

On the other hand, cities even as far north as New York can still realize significant benefits.  If every roof in a given city were entirely painted white, the urban heat island effect could be reduced by 33 percent, the researchers found.  NYC would see a cooler summer afternoon by almost 2 degrees Fahrenheit  “This would cool the world’s cities by an average of about 0.4 degrees Celsius (0.7 degrees Fahrenheit), with the cooling influence being particularly pronounced during the day, especially in summer,” the National Center for Atmospheric Research said in a statement, as reported on MSNBC.

The model did not have enough detail to capture individual cities, but it could estimate changes in larger metropolitan regions. “The New York area, for example, would cool in summer afternoons by almost 1.1 degrees Celsius (2 degrees Fahrenheit),” NCAR said.

Plus, factor in that we’re having record high temperature days lately and its not likely to turn around anytime soon, so the future economics of a white or lighter roof may improve in the near future.

In colder months, a home or building with a white roof may require slightly more heating because it is not retaining as much heat.  However, the reduction in summer A/C related energy consumption outweights the demand for winter heat for two reasons.   First, the sun simply shines longer and more directly in the summer and has more time to heat the surface and secondly, the cooling process typically uses a lot more energy compared to the amount of energy needed to heat our homes.

White, cream, or gray: take your pick.  Residents in the American South and Southwest smartly opted for  white back in the early 1900’s before we had central air-conditioning.  Soon enough however, they and other folks in sun-blasted areas began switching to darker roof colors when A/C arrived.  Turns out that was shortsighted.

Interested in finding some money for your white roof project?  The government may help.  These roofs can qualify for federal, state, or local tax credits since they are an energy efficient retrofit. 

At the federal level there is a Residential Energy Efficiency Tax Credit which can compensate you up to $1,500 for this type of project.  Check DSIRE (Database of State Incentives Renewable and Energy Efficiency) for possible state and local incentives available in your state and municipality. A remedy to this colder climate white roof short-coming is being worked on by a team of MIT researchers. 

In 2009 they developed a prototype of tiles that can change color based on air temperature – named Thermeleons!  The idea may become a option sometime in the future.  We understand that some roofing material manufacturers are working on a dark surface color with a white under-layer that still delivers the dark aesthetic appeal but lowers the overall heat absorption rate of the roof tile.

Current U.S. Energy Secretary Steven Chu (see video below) says that turning all the world’s roofs white would eliminate as much greenhouse gas emissions in 20 years as the whole world produces in a year. largely because of the urban heat islands. Why stop at roofs?  Secretary Chu said that society should also think beyond buildings. “If all vehicles were light-colored, there could be considerable savings because then you can downsize the air conditioning, and downsizing the air conditioner means more efficient air conditioning and a considerable reduction in energy.”

Check out the recent Green Blizzard post about white color cars.

White is a color after all – consider this rationale.

  • Cost no more money to switch from dark to white
  • Quickest lowest way to reduce your global emissions
  • Reduces heat island effect
  • Saves you a TON of money
  • Saves you a TON of CO2

If, for aesthetic reasons or curb appeal, you still prefer the dark roof, consider applying a white roof to the unseen roof areas or the backside of your home or building.

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About the author

Kenny Frankel

As graduate of the University of Maryland, Kenny has a major in Environmental Politics and Policy, so he's undoubtedly a guy well versed in environmental issues. Now, post college he is a practitioner of sustainable living and employed by solar installation company. We all will have a deeper green perspective after reading his articles because he brings a big picture insight to our everyday purchase decisions and even recycling.  As an early staff writer for Green Blizzard, Kenny covers environmental policy, big-agricultures impact on the environment, solar energy, recycling, and products made from recycled materials.