How Painting Your Roof White Can Help Save The Planet

Another post for you, written by Ben from Big Green Smile. This time he talks about painting your roof…

“Drive smaller cars, install efficient light bulbs, insulate our lofts, plant trees and don’t fly. Most of us are familiar with the dos and don’ts of climate change but here is something new for your arsenal in the fight. Paint your roof white. A little bit ‘out there’ perhaps but this is the vision of Hashem Akbari, a US scientist based at the Lawrence Berkeley National Laboratory in California.

Ben

“The Greeks have been doing this to their beautiful villages for centuries of course but Hashem Akbari believes that painting the grey and let’s face it rather dull buildings of our own towns and cities white will have a tangible benefit in curbing global warming. White/light roofs reflect approximately 50% of the sunlight whereas on black/dark surfaces this is just 10-20%.

“Akbari calculates that a mass movement to paint our roofs white could result in 0.03% additional sunlight being bounced off the earth; enough to cancel out a tremendous 44bn tonnes of CO2, which is the projected increase for the next decade.

“With carbon emissions still rising, painting everything white is not the only answer, by Akbari’s own admission. The idea needs mass contribution for it to be effective but compared to other measures it is relatively simple, does not need protracted long negotiations for it to be effective and is relatively cheap.

Big Green Smile

“Studies in Los Angeles have shown that replacing two thirds of rooftops and road surfaces with reflective surfaces would cool the city by 2-3C. Although the UK does not have the hot climate of California there are benefits to be had anywhere that has need of air conditioning, and that certainly counts London. Akbari would ultimately like to see his idea included in carbon offsetting schemes and has calculated that every 10 square meters of re-painted reflective surface is preventing the release of a ton of carbon dioxide.

“Time to get the painting clothes on then.”

2 thoughts on “How Painting Your Roof White Can Help Save The Planet

  1. a quick explanation of why white paint works to cool the planet

    1 around 50 percent of sunlight is visible light

    2 around 50 percent of sunlight is heat

    3 visible light is a frequency of light NOT absorbed by the atmosphere

    4 some HEAT (infra red) from the sun IS absorbed by the atmosphere directly (greenhouse gasses which makes the atmosphere warmer).

    5 HEAT from the sun also warms the surface of the planet and this HEAT is then radiated back into the atmosphere again being absorbed by greenhouse gasses.

    6 visible light is poorly absorbed by the atmosphere, some of it gets reflected back by the atmosphere.

    7 the visible light that doesn’t get reflected back by the atmosphere is either reflected by the surface (eg a snow field) or absorbed by the surface (an asphalt carpark/ road). this absorbed light heats the dark surface. this heat is then radiated into the atmosphere and is absorbed by greenhouses gasses makiig the atmosphere warmer.

    8 by painting your roof white and other surface you reflect around 50 percent of the visible energy from the sun, a significant amount of this is reflected back into space WITHOUT heating the atmosphere.

    9 by painting enough roofs you make buildings cooler and cool the atmosphere. air conditionig works easier to cool houses because they are cooler, perhaps you wouldn’t even need air conditioning?

    if you are thinking of using white paint to cool your roof you will need a special white insulative paint that both reflects the visible frequencies of light and stops infra red frequencies from heating your roof.

    Like

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