Roman Sturgis Take care of each other and make good decisions.

July 31, 2009

Roof Color Change

Filed under: Blog — Roman @ 10:56 am

Earlier this summer Secretary Chu was in London talking about “cool roofs”. For those of you not down with the lingo, a cool roof is a flat topped roof painted white. Desert cultures have long known about the benefits of white stucco, which reflects heat. As opposed to black, which absorbs heat. Chu says he has a colleague who reckons that changing all flat-topped roofs to white and changing the color of all the roads in the world to a concrete color, as opposed to a black-top color, would reflect sun back into space and cool the planet. They say it’d be the equivilant of 44 billion tonnes of carbon dioxide, offsetting the last 18 years of car emissions.

Of course, a project on that scale is total fantasy.

But what about the homeowner who wants to absorb heat into his home in the cool months, and reflect heat in the hot months? Someone in Arizona or Florida might not have to worry about the cool months as much, so they can paint their roof white and keep it that way forever. Someone in Alaska is happy with their black shingled roof, because they want all the heat they can get.

Most of us, however, live in areas where the temperature changes, and so ideally, we’d have a roof that changes, too.

My first idea, which I floated to a friend in the renewable energy field, was to use the same technology as the Kindle to cover roofs. (A Kindle screen is a sheet of pores that are naturally white, but when activated by an electrical current, turn black. This is what gives the Kindle that “print” look.) Using a Kindle like surface on roofs would allow you to change the color when you wanted, or synch it to the thermostat. (OR be programed to display messages/pictures for holidays, Santa, God, potential alien visitors, etc.) But my friend wisely pointed out that a world full of Kindle roofs would be an environmental disaster, not to mention expensive.

Instead, he suggested, look at thermochromatic paints, that change at a certain temperature, like mood rings. So I did some research and found that some paints exist, but their changing point is too high: 86 degrees F. We’d need something around 70.

I’ve asked a friend at Sherman Williams to get on this project. I’ll let you know what he says.

But seriously, this is a good idea, right? And simple, and achievable… Makes you wonder why no one has done this already.

Oh, that’s right. Home owner associations.

2 Comments »

  1. BA-DUM BUM… CHAAAAA! Well played on the last line sir. Well played.

    Comment by Rev — July 31, 2009 @ 11:33 pm

  2. You might consider other strategies beyond best you can manage IR reflectoins which simply addresses but a small sub set of possible strategies. A Trombe wall is available to absorb year round, with variable effectiveness depending on cloud cover and time of year (solar incidence angle mostly).
    Another of the home uses year round is heating domestic water for washing and bathing. A small absorber sized for this load would backout the fuel combustion for electric or gas.
    solar shutter, either static or dynamic is another absorber when you need it, reflector when you dont
    As you’re becoming aware thru the hvac study, this is all about heat flow….energy flow, not absolute statics.

    Comment by rob — September 24, 2009 @ 10:20 am

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