White Paint: It’s Not Just For Apartments Anymore

by Venomous Kate

Looking to lower your cooling costs and help save the planet? The answer may lie in a few buckets of white paint.

According to a Lawrence Berkeley Labs study, painting roofs white may not only help cool the planet but may also reverse “global warming”. It works for t-shirts, after all. And there’s no doubt a reason why Mediterranean homes are primarily painted in light colors. Painting your roof white could work the same way, too.

Hashem Akbari, a physicist at the Lawrence Berkeley lab, just released a study showing that the average American 1,000-square-foot white roof could offset 10 metric tons of carbon dioxide.

According to his data, roofs constitute 20 to 25 percent of urban surfaces, while pavement is about 40 percent. Therefore, if all of those surfaces were switched to a reflective material (or color) in the 100 largest urban areas in America, his calculations show, this would offset 44 metric gigatons of carbon dioxide. That’s more than all countries emit in a single year. Further, that’s worth about $1.1 trillion at current carbon trading rates.

Of course, first we’d need a study to find out whether painted roofs leak toxic emissions into the air when subjected to high summer temperatures, particularly once the paint begins to decay.

10 Comments to “White Paint: It’s Not Just For Apartments Anymore”

  1. I thought they were measuring air temperatures- not ground temperatures
    wouldn’t reflecting all that heat back into the atmosphere increase air temps?

    Maybe we should use tinfoil- reduce global warming AND reflect all those alien transmissions

    Alien transmissions:

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  2. Pardon me for sounding so Suburban Housewife but as I stare at what appears to be miles and miles of picket fence that needs scraping and repainting –


    (Light grey shingles on our roof. Hope that’s good enough.) Hah.

    Margis last blog post..I’m doing it for me

  3. Will…
    Please take a moment to think about the question that you asked. The heat has already been through the atmosphere and is being absorbed by objects on the ground that slowly release that heat… back into the atmosphere.

    Jeffs last blog post..Post Ike Rant

  4. I guess what I don’t understand is this.

    There is a finite amount of heat energy coming in.
    Let’s say 100 units
    Now- if the atmosphere absorbs 20 units as the sunlight passes through- that leaves 80 units

    if the 80 units is reflected back into the atmosphere it’s eventually absorbed (yes/no)

    if it’s absorbed by a parking lot- it’s eventually reflected back into the atmosphere where it’s absorbed (yes/no)

    unless the heat energy is converted (ie photosynthesis? and perhaps even sound and motion energy by causing the blacktop to crackle and move) doesn’t the law of conservation of matter and energy require that that entire amount of energy be used up?

    Soooo….. I can see how having plant life could reduce the air temperature- or even conceivably solar panels- but the color of the surface would seem to me to only change the time frame for the exchange of the heat over a longer period of time

    Unless of course this reflected heat energy escapes our atmosphere

    Just wondering

  5. So what impact does a white roof have on a building’s heating costs in the winter?

    Sometimes, absorbing solar heat ain’t a bad idea.

    Brian J.s last blog post..The Noggle/Lileks Video Collection Solidarity Approaches

  6. Now that would be a great idea- shingles that changed color based on the air temperature

    Dark when it’s cold
    Light when it’s hot

  7. You better get a patent on that idea, Will. It’s a good one.

  8. In simple terms, the heat that passes through the atmosphere to the surface in a finite amount (for sake of discussion) has a value that gets returned at some point whether it is reflected or radiated by objects that absorb it.

    The sunlight that pounds the side of my house all day in the summer heats up those bricks… and those bricks radiate that heat right back out when the sun goes down. Now, if those bricks were white, they wouldn’t absorb nearly as much energy. If I don’t have, basically cooking stones on the outside of my house or roof, I’m not paying as much to counter the heat effect on the inside via AC and such.

    There is no total heat gain or loss… Just an offset. If everyone winds up reflecting heat away from their homes and businesses, less is spent on countering the effects. That’s less energy expended, and on and on.

    I hope that made some sense.

    Jeffs last blog post..Bet It All

  9. Oh great, this will become the new “economic discrimination” factor. To wit: rich folk can afford to paint their roofs and reflect back all that heat, but poor folk can’t so their cooling costs will go up.

    Anyone want to place bets now? Anyone? Anyone??? Buehler???

  10. It’s an interesting enough idea, though I don’t think I can climb out on our own roof and paint the black shingles white. Not only is the paint unlikely to stick, but the association might have some problems with that remodeling decision.