Cool roofs

White roofs reflect sunlight back into outer space. New Zealander Ian Montjeese, an inventor-come-physicist with degrees in engineering and architecture, reckons painting the town white, rather than red, could halt global warming. He says that if 50 percent of the roofs in New Zealand were painted a pale colour, the cooling effect would cancel the warming produced by New Zealand’s vehicles—permanently!

Polar icecaps keep the planet cool by reflecting sunlight back into outer space. By painting roofs white we can mimic this natural process, says Ian Montjeese.

Hasn’t the year gone quickly. I swear it was February last time I blinked. And now it’s mid-September, which means in less than four weeks it’s time for one of the biggest events on the environmental calendar: 350’s Global Climate Working Bee.  I remember last year on this day, I was on a plane flying from Dunedin to Wellington which made me feel decidedly guilty. This year I have vowed to be different.

Photo by Muffet via Flickr

First stop was the website to see what activities are happening on the 10 September 2010. One in particular caught my eye. Initially, I was struck by its simplicity. It does seem a bit of a no-brainer and I wondered why no one had thought of it before.

Here’s the gist: one man has decided to take on global warming by trying to encourage people to paint their roofs white.

Ian Montjeese, an inventor-come-physicist with degrees in engineering and architecture, is trying to spread the word about white roofs. He’s in good company. US Secretary of Energy, Dr Stephen Chu, has been trying to implement similar measures across the States this year.

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New research shows that by painting the roofs of buildings white or light coloured instead of Baked Earth, Beaten Track, Black Magic, Brownie Points or Birthday Suit, we can halt global warming.

If 50 percent of the roofs in New Zealand  were painted white, this would have a cooling effect that would cancel the global warming produced by New Zealand’s vehicles, permanently.

Ian has done calculations of his own and says: “If 50 percent of the roofs in New Zealand (roughly 18,000 football fields) were painted white (or pale coloured) this would have a cooling effect that would cancel the global warming produced by New Zealand’s vehicles, permanently.”

Ian had the idea three years ago and tried to contact government departments who didn’t really take the idea seriously. However this year he plans to get his paintbrushes out and start making a difference.

“I was thinking about how I could make a really significant condition to global warming, not just some little thing like turning the kettle off at the wall or putting the exact amount of water in. Something huge. And it just came to me about how the polar ice caps reflect sunlight back into space and how we could mimic that, and I did some
calculations and they all stacked up.” 

This is just the beginning—the white idea can be applied to roads, pavements and car exteriors, just to name a few.

The basic physics

Photo by darren_ck via Flickr

When a roof is white, or an object is white, it reflects light. When sunlight is reflected off a white roof, about 60 percent is reflected (depending on when you last gave it a good wash) and most of this goes back into space. When a roof is black, brown or dark coloured, it gets converted to infrared wavelengths, which then get stuck in the blanket
of greenhouse gases that warms the earth. This is a
natural phenomenon, but humans are adding too much greenhouse gas to the ‘blanket’, which is going to make this planet a scary place to live unless we do something to cool it.

If you aren’t sold yet, white roofs can also keep your air
conditioning costs down! Due to the cooling effect of the white roof, it can lower the price of cooling a building by 10–15 percent!

If white just isn’t your thing, don’t worry, there are also a whole host of cool-coloured paints available and paints with high reflectivity from places like Resene. But if you’re keen to reduce global warming—rather than wanting to keep your roof a handsome chocolate brown—then Ian insists  white is definitely the colour to go for. It has a reflectivity of 60 percent compared with 28 percent of cool colours.

So, where do I sign, I hear you asking.  Sign up on 350.org.nz or for more information on Ian’s idea, or to donate so he can get this thing started, contact him directly: [email protected].

For more information on cool roofs read here