Brown versus White Roof?

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I believe when I was a youngster, my dad put a white shingled roof on our house and as I recall, we were the only one or two in a large subdivision with a white shingled roof. This was on Long Island, NY. I don't recall them ever talking about the electric bill but I was probably too young to care. My personal thought is that a white shingle roof is probably minimally beneficial because since I've lived in Texas and traveling around Houston and Austin, I don't recall seeing any white shingled roofs. I would think with the heat we get for many months a year, if it were really beneficial, they would have a lot more of them around here. So my conclusion is that my father (a builder then) and the homes I see now, do it for cosmetics more than anything else.
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Doug wrote:

I think the reason you don't see light-colored roofs in a Texas urban environment, or any urban environment for that matter, is they discolor from the gunk and particulate matter in the air. The roofs, moreover, don't discolor uniformly. They streak and in general look just horrid.
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wrote:

Yea but the colors on the roof now show the same thing so I don't think that's a white issue. I admit white might show a bit more contrast when discoloring.
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wrote:

In my opinion, if you live where there are cold winters, a dark roof will add heat in winter too, thus saving on heating costs, but that will be offset in summer by higher AC bills. If the climate is in the south without severe winters, I'd go for a light colored roof.
A compromise is a medium colored roof such as a gray or tan. Personally I went with a tan on my roof, in a more north climate with cold winters.
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On Sat, 26 May 2012 17:20:58 -0500, snipped-for-privacy@nothing.com wrote:

Funny, I see *zero* light-colored roofs here. It could have something to do with mold, or it could even be the red dirt. ;-)

As others have said, ventilate the attic space well enough, then choose the roofing color you like the best. You wouldn't paint your house black to save a few $$, would you?
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snipped-for-privacy@nothing.com wrote:

That is completely false.
That is so wrong, it's not even funny.
Your attic should be insulated such that there is NO ability to tranfer heat IN ANY DIRECTION to or from the interior of your house. Think about it. If any heat was being conducted from your attic into your house IN THE WINTER, then can you imagine how much heat would be conducted into your house IN THE SUMMER ?!
But the idea that your attic would even get warm enough in the winter to have any useful heat is the biggest wrong assumption in your statement. For one thing, the angle of the sun in the winter, the hours of available sunlight, the likelyhood of more cloudy days in the winter -> and the fact that your roof could be covered with snow all combine to give zero usefulness for having dark shingles in northern-latitude homes as some form of energy (heat) capture.

It's still a flawed premis in the first place to propose that dark shingles have heat-accumulating benefits for homes during the winter months.

My climate is similar to Detroit, Buffalo, Cleveland or Toronto. I have a tan roof. The upper floor has a pyramid-shaped roof (basically comes to almost a point at the top). During the past week, the outside air temperature has reached between 80 and 85 f, completely clear sky (no clouds). The roof is not shaded by any trees at mid-day. Without the roof fan running, the temperature in the attic will reach 135 f. With the fan running, it will reach 115 f. Temperature is measured halfway up one side of the roof, about 1" under the roof decking.
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That is completely false.
That is so wrong, it's not even funny.
If there were "NO ability to transfer heat IN ANY DIRECTION to or from the interior of your house", there would be no need for a furnace or AC, at all. The fact is that heat transfer is finite and proportional to the delta-T. Lower it and you *will* save money. The heat transfer is really delta-T/R, so there are two knobs to turn. True, R is usually the easier knob to turn but your statement, as made, is wrong.

There is warming of the attic space in the Winter. Attics *should be* designed to stay cold, but there is heating due to the sun. If there weren't, ice dams would be unheard of.

But physics is *so* much different in the Winter. <giggle>
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

I didn't say that it was possible to have zero heat transfer.
So stop being disengenous.
You know dam well that a house can't "harvest" heat from the attic in the winter.
You know dam well that your goal should be to have as little ability as possible to transfer heat to or from the interior living space to the attic. And given that goal, that the very idea of having dark shingles for some kind of heat-benefit in the winter is crazy.

In the winter (as is the case in any season) -> an attic space can (or WILL) get warmer THAN OUTDOOR AMBIENT TEMPERATURE.
So what?
What good is it when it's 20 F outside and 30 F in my attic - when I want it to be 72 F inside my house?
What am I going to do - install a heat pump in my attic to extract the paltry amount of extra heat in the attic space?

You did not comment on that statement.
Why?
Because it was true / accurate?
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Read what you wrote.

Write what you mean. Or learn something. Either way...

Wrong. Heat transfer is delta-T/R. Lower delta-T means a lower heating bill.

"As little as possible" is *not* zero, as you said. For every 1F you can drop delta-T, you save something like 2-3% of the heating bill (assuming an average 30-50F temperature rise).

It changes delta-T, that's what.

Because you only raising the temperature 42F rather than 52F, a 23% savings on heat escaping through the ceiling (which you said was zero, above). Is 23% 0?

I know it's almost impossible, but you might try thinking.

Because you're a liar? Any heat in the attic *will* help. For completely separate reasons, you want to minimize the heat in the attic, but it *does* matter, here.

No, because I already had.
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Tony Sivori wrote:

If you live in an urban environment, the white shingles will turn brown given enough time. The particulate matter from auto exhausts - and other pollutants - will stain them, but not evenly.
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after the Summer rain". ;-)
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snipped-for-privacy@att.bizzzzzzzzzzzz wrote:

In my part of the country, we call a mixture of red clay and water "adobe."
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Nope, don't know that one. Maybe if you hum a coupla bars. ;-)
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On 5/25/2012 11:46 AM, Tony Sivori wrote:

IF (note the IF) the attic is insulated properly, the roof color will be of no consequence. You will also be able to see the fungus on the north side a lot more with the white than with the darker color. If your roof does not have a north side, then disregard.
--
Steve Barker
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