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Old 08-25-14, 09:07 AM   #11
AC_Hacker
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Quote:
Originally Posted by dablack View Post
A little back ground. If you search my old posts, you will see that we were building a house a year ago. Right before we moved in, that house was lost to fire.
So sorry about the fire...

-AC

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Old 08-25-14, 05:08 PM   #12
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http://ecorenovator.org/forum/solar-...bottom-up.html: See this thread. I'm not a big fan of using multiple layers of radiant barrier. A least here on Earth. Air can easily short circuit multiple layers though the process of conduction and convection. Here on Earth I would limit it two a maximum of two layers with a generous airspace between them. Btw, I'm still working on my project, which is coming along. And for anyone who doesn't know it, if you live in a mild climate then you can use a radiant barrier for both cooling and heating. That's providing your house is quite tight and well insulated. Again, see that thread. I too am sorry to hear of the unfortunate happenings with your previous house.
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Old 08-25-14, 07:41 PM   #13
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NOTE: I have moved this post over to THIS_THREAD as it is a better fit there.

-AC
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Old 08-26-14, 02:46 AM   #14
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AC, I'm not sure who you are accusing of being smug about insulation? I am, as far as I know, the first person here to promote a project using radiant barriers in a form other than for cooling. Have you even read and understood the concept behind that thread I just mentioned? All I'm saying is that while the concept of using multiple layers of radiant barrier may be good in principle in a vacuum it won't work as you are advertising. But hey, if bringing physics to the table is being smug on this forum then I plead guilty. However, if you really believe that the stuff sold in the UK has over an over 20 R value per inch then I have this bridge I'm selling that you'll find is a real bargain.
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Old 08-26-14, 08:39 AM   #15
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AC Hacker,

It was a year ago in July, so we are pretty much over it now (emotionally), just not finacially. Once the new house is done, we will be well on our way to finacial health.



Exeric,

Thanks for the info on your project. I like the idea of using hot attic air to heat a house (if you need heat). Here in East TX, we don't really need much heat. My family and I like it cold and don't really turn on the heat except late at night probably two months out of the year when an attic would have already cooled down. Also, I will have a sealled attic. For those two reasons, I can't really use anything from your project but I do find it interesting. I had friends that would put garbage bags over their turbines in the winter to retain heat in the attic. It worked well for the Dec/Jan/Feb heating period.

About the multi layer radiant barrier....well, who knows. I worked at NASA for 10 years and sometimes things that work in space don't work on earth. Sometimes they do. I would need to look into it much more before I said yes or no.

Austin
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Old 08-26-14, 09:13 AM   #16
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Removed because of double post

Last edited by Exeric; 08-26-14 at 10:07 AM.. Reason: removed because of double post
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Old 08-26-14, 09:21 AM   #17
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dablack, it might work for you or it might not. I haven't finished the project yet so it's premature to claim a proof of concept for a radiant barrier heating a home. However, your situation might not be that different from mine. Most of the heating needs come in the middle of the night for both of us. It really depends on one's home being very airtight and well insulated. I think of it like capacitor filtering for an AC power supply. As long as you don't draw too much current then a smallish capacitor should be able to supply the current to the load until the next replenishment cycle. So, as long as your house can retain heat, and its in a mild climate, then one should be golden. In theory anyway. (Theory has a way of going awry when theory meets world.) I should add that the same radiant barrier used to concentrate heat will work in the usual way to cool the house in summer by reflecting heat away from the attic. So it's a 2fer for places like Texas and California which both have hot periods in summer.
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Old 08-26-14, 09:29 AM   #18
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Exeric,

One of us isn't understanding. Right now I'm not sure who. Maybe I don't understand what you are building. From what I saw of the thread, it looks like you are capturing and using heated air from the attic. This heated air is heated because it is from above your radiant barrier and below your roof deck. Correct? In the summer you will vent it. In the winter you will use it. Right?

I will have a sealled attic. No venting. No heat to capture. My foam and radiant barrier (if I use one) will be external to the roof deck. I'm using attic trusses that give me a 8' wide room in the attic. I have a gable roof with no dormers and my house is 52' long so that gives me a 8' wide room, 52' long. In that room you will see the roof deck and rafters. That is it. Everything else will be external. I don't want any heat to get into my attic. Since there will be very little heat there, there is nothing for me to capture. \

My layers from the bottom up will be attic truss, OSB roof deck, grace triflex underlayment, three or four layers of 3/4" dow foam board (taped seams offset between layers), maybe radiant barrier, verticle 1x4 boards set at 24" OC, horizontal 1x4s set at 24" OC, and then a metal roof. The area between the radiant barrier and roof will be vented at the peak. That is a metal roof vent and not an attic vent.

thanks
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Old 08-26-14, 09:34 AM   #19
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Yes, you are right. I was thinking generically about climate. I don't think it will work with your particular construction details. It really does require very specific house construction details to have the potential to work.
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Old 08-26-14, 11:18 AM   #20
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Quote:
Originally Posted by Exeric View Post
...All I'm saying is...
I have moved this post from this thread (3/4" Insulation), over to Space Suit = Multi-Layer Insulation (MLI), where it is really a better fit.

-AC

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