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Full Version: Solar roof coverings- passive heat?
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Hey everyone- first post here. I love these forums, and they've been an excellent resource, but I had an idea for something and I can't seem to find any posts about it.

My wife and I are planning to full time in an airstream in a year or so, and part of this time will be spent in colder than ideal temperatures. I've been researching skirting ideas, and the EZ snap RV skirts appeal to me because they can be installed without drilling, and they come in black for added passive heat.

My question is, couldn't the same idea be applied to the roof? (Given consideration for the vents, etc?) I could cut a custom black vinyl fabric cover to snap in place to pretty much act as a counter to the white roof on an airstream.

Has anyone tried something like this?

Thanks!
There's insulation (I assume) between the roof and ceiling that's supposed to keep heat out to some degree. So the question is whether a black roof cover would be able to transmit enough heat to overcome the R value of the insulation. Meanwhile, heat wants to rise, not fall into the living space. I think it's easier and would probably work metter to position the trailer so that as much sun as possible comes in the windows.
That's true, and those are good points. At the same time, new airstreams come with white roofs, and plenty of people paint the the older ones white, so you'd have to think the roof color makes a difference. It shouldn't just go one way, right? The windows would surely also make a difference during the day as well (and then hurt at night, ha.)

As someone who has owned a black car and a white car, both the same model, and in immediate succession, I can tell you color makes a huge difference. Granted, a car doesn't have much insulation.
(12-12-2016, 03:50 PM)Mumbly-Peg Wrote: [ -> ]That's true, and those are good points. At the same time, new airstreams come with white roofs, and plenty of people paint the the older ones white, so you'd have to think the roof color makes a difference. It shouldn't just go one way, right? The windows would surely also make a difference during the day as well (and then hurt at night, ha.)

As someone who has owned a black car and a white car, both the same model, and in immediate succession, I can tell you color makes a huge difference. Granted, a car doesn't have much insulation.

My thoughts on this......black absorbs heat and white reflects so it will probably have some positive effect. I doubt the insulation is so adequate that it will not allow some heat transfer. If anything a black roof might slow the loss of heat from the Airstream to some degree.

I don't remember the exact numbers but I had lab data on the temperature difference of cars of different colors. The difference from white to black was in the range of about 130* for white car and about 180* for a black car in the sun with colors in between the two. Pretty amazing.
Thanks for that, Greg. I totally believe those numbers. I love driving a white car for that reason, actually. I argue with my brother in law who prefers the "murdered out" look. (Black paint, dark tint, black interior, black rims)

So suppose the roof of the airstream could be 60 degrees instead of 40, the heat loss would have to be significantly reduced, even if it would only be effective for 3-4 hours of the warmest part of the day, I'd have to think the propane usage and comfort factor would be positively effected.

Unless someone else pipes up, I might be the guenea pig!
I'm with vtwinkicker -- The black should absorb some heat if it's sunny -- it doesn't have to overcome the R value of the insulation or anything else. But it should be useful just to help reduce the absorption of cold from the outside metal, as well as slowing the loss of heat from the inside.  IMO.
A black surface will absorb more heat in sunlight, and also radiate more heat at night due to higher emmissivity of dark colors.

For a black covering to effectively transmit more heat in wintertme to interior, it would have to be in direct contact with the roof, heating that, and then at night one would remove the black covering to minimize heat loss.

Lots of work, little result, perhaps not even measureable, depending on amount of existing insulation.
I don't see removing every night as a benefit. If it's a thick vinyl/canvas material, it should almost act as a thin, mostly ineffectual layer of insulation. I don't see how it could cause any heat loss when the sun is down.
(12-15-2016, 10:48 AM)Mumbly-Peg Wrote: [ -> ]I don't see removing every night as a benefit. If it's a thick vinyl/canvas material, it should almost act as a thin, mostly ineffectual layer of insulation. I don't see how it could cause any heat loss when the sun is down.

Go argue with physics.

https://en.wikipedia.org/wiki/Emissivity

Whether it makes a measurable difference to your prospective interior's night time temperature, is of course arguable, until some actual data proves it one way or the other.
x2 on what Stern is trying to tell you, he is right. another point if you lay a tarp flat on your roof, if there is any dirt on your vehicle or on the tarp and the wind kicks up it's going to be like a big sheet of sandpaper. highdesertranger
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