Cool Roofing

Discussion in 'Architecture & Engineering' started by Orleander, May 28, 2009.

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  1. Orleander OH JOY!!!! Valued Senior Member

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    Its been in the US news that we can help save the planet by painting our roofs white. Seems like other countries have known this for ages.

    There are already places that specialize in it. Is this a good idea or has it been blown out of proportion? Other cultures do it, why is it shocking to suggest Americans should just paint their roofs?

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  3. draqon Banned Banned

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    how exactly will white painted roofs help and with what? the greenhouse effect?

    I am guessing it is because of reflectivity of white, right?
     
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  5. Oli Heute der Enteteich... Registered Senior Member

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    It depends on the temperature differential: outdoor vs. indoor.
    White is a poor radiator so if it's warmer inside then the heat loss will be lower - lower heating bills since you aren't paying to heat the atmosphere.
    Alternatively, if it's very sunny (not just hot) then the heat transfer to indoors will be low (reflecting a lot of the sunlight) making it cooler indoors than outdoors in direct sunlight (presumably that's why it's done in places near the equator).
     
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  7. draqon Banned Banned

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    yo the best idea would be to have solar panels generate electricity on every roof of every city
     
  8. spidergoat Valued Senior Member

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    I don't think there are white asphalt roofing shingles available. Every thing else is expensive. It would also discolor rapidly.
     
  9. Orleander OH JOY!!!! Valued Senior Member

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    But even a lighter colour would be better right?
    Here in MI we tend to go towards darker colours because it absorbs sunlight in winter. Our roof is dark green.
    We have stuck to a gravel driveway vs asphalt because of the heat though. I didn't want dead grass/plants all up and down my driveway
     
  10. spidergoat Valued Senior Member

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    I suppose. I'm about to get a new roof, and presently the house gets much hotter than the ambient air temperature during the day. Some of that has to do with lack of insulation.
     
  11. Xylene Valued Senior Member

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    White painted roofs would make a lot of sense in Florida, along the Gulf Coast or across the Southwest--it's not called the blazing Southwest for nothing...

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  12. nietzschefan Thread Killer Valued Senior Member

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    Yup - that should be law.
     
  13. cosmictraveler Be kind to yourself always. Valued Senior Member

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    White is good during the summer time but come winer you would want something to absorb the suns heat, a darker color would be better then.
     
  14. Xylene Valued Senior Member

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    It would keep the housepainters busy, anyway...

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  15. svenglezz Registered Member

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    Don't they have paint that changes colours?
     
  16. mugaliens Registered Member

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    Whaaaa... t? And reflect all that free solar electric and hot water heater energy back into space instead of using it to reduce electric and gas bills?

    Even southern climes have cold spells, and solar heating goes a long way towards reducing those electric bills.

    Speaking of which, if you're reflecting all that energy back into space, then turning around and heating the unit anyway, there's absolutely no gain.

    On the other hand, if it's summertime, then reflecting that heat upwards makes sense.

    But you still need hot water...

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  17. Pinwheel Banned Banned

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    The problem is the energy required to manufacture that many solar panels vs the electricity you get in return may diminish over time. Solar water heaters on the other hand are great, I've seen these installed up close and they produce hot water even on overcast days. Better than using any electricity to generate heat.

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    But it also has similar drawbacks as with electricity generating panels, but are a little more efficient.
     
  18. Grim_Reaper I Am Death Destroyer of Worlds Registered Senior Member

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    Yes there are white shingles how ever it only takes a few years for them to turn Grey and look really really ugly. Just imagine housing in a million dollar plus subdivison looking like something from downtown detroit when it comes to the roof. Not likely to happen unless it is mandated that it has to happen and then there would be the cost factor who pays for it the owner or the government forcing the owner to change the colour of the roof.
     
  19. Grim_Reaper I Am Death Destroyer of Worlds Registered Senior Member

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    And the problem with Solar pannels is the return on investment it is way too long for the average home owner to invest 20 to 30 plus on panels and connecting harware that is only rated to last 15 years when the return on the investment is between 5 to 10 years. And then there is the issue of a land owner that has multiple buildings things like this could cause a large problem very very quickly.
     
  20. Read-Only Valued Senior Member

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    Mine were a light grey when installed several years ago and have been bleached by the sun so that they are actually whiter now. (I don't live in or near a city.)

    Don't see your problem with who pays. Just install the whiter ones when your next replacement is due. That would get a fairly large number of them done every single year. 10 years would probably see 50% converted.
     
  21. Grim_Reaper I Am Death Destroyer of Worlds Registered Senior Member

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    Well yours are likely whiter because you do not live in a city and many cities are much worse then others. And 50% of the roofs replaced in 10 years not likely considering the average min live is 15 years on shingles and can go as high as 40 which I personally have on my own home so I would be in me 90's give or take before that roof needs replacing baring natural things like wind or hail damage. in 10 years you would be lucky to see 10 percent replaced and a lot would not get replaced as the owners cannot afford or will not afford replacement due to either rental or personal reasons so yes. A mandated replacement of the roof's would have to involve government funding period.
     
  22. Read-Only Valued Senior Member

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    Actually, I was considering the average life-span to be 20 years when I said 50% in ten. (That's a *very* simple application of statistics.) But if it's closer to 15 years - as you say the average is - then it would take even less time. So I still do not see your claim about paying as being a major issue at all.

    Those with 40 years, such as yours, are so far from the average that they wouldn't be worth counting. Metal (steel) roofing is becoming more popular in the U.S. every year, too. It's available in white, has a long life, and could be repainted with a boom truck (spray-on enamel) in less than two hours every 20 years or so.
     
  23. cosmictraveler Be kind to yourself always. Valued Senior Member

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    I've had ...

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    On my roof for over 50 years now and they do a good job in the summer and winter. They aren't to bright to reflect all of the heat away yet not to dark either to absorb heat. Having a clay tile roof is the best way to go I'd think for the tiles last a very long time and serve a duel purpose as well.
     
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