Papercreters: [papercreters] Using Aluminlum foil inside a wall to reflect heat

Saturday, September 11, 2010

[papercreters] Using Aluminlum foil inside a wall to reflect heat

Judith,

I'm not a physicist, but your description of putting aluminum foil on top of reed fencing and, presumably, under papercrete with the intention of it reflecting the heat back into the room didn't sound like it would work as intended.

I think the reed fencing would absorb the heat and transfer it to the aluminum foil via conduction and then from the aluminum foil on to the papercrete via conduction. The aluminum foil (in this case) will not reflect heat unless it has an air surface or space next to it.

I think you should save your effort in this case. See the excerpt below from an article on the net, THE PHYSICS OF FOIL HEAT GAIN/LOSS IN BUILDINGS. I believe the excerpt speaks directly to the issue you are considering. I added the comment in brackets [].

http://www.radiantbarrier.com/physics-of-foil.htm

"Reflection and emissivity by surfaces can ONLY occur in SPACE [air space for this example]. The ideal space is any dimension 3/4" or more. Smaller spaces are also effective, but decreasingly so. Where there is no air space, we have conduction through solids. When a reflective surface of a material is attached to a ceiling, floor or wall, that particular surface ceases to have radiant insulation value at the points in contact."

Dan

--- In papercreters@yahoogroups.com, JUDITH WILLIAMS <williams_judith@...> wrote:
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>
> I'm sure many of you know what it feels like when it's 4 in the afternoon and you've been working for hours and you still have a half a mixer load of slurry to get rid of. That's what happened to me today. It's after 8 and I just got home. Did the last of it practically in the dark. But I am almost ready to start the roof. I have someone coming tomorrow evening to work with me on Monday and Tuesday and I am determined to get this roof done.
>
> So anyway, I tried putting some joint compound in the slurry that will be going on the wall where the viga is. It seems to be sticking very well. I'll know for sure when I check on it tomorrow. I used some reed fencing for the ceiling and will put aluminum foil over that to reflect heat back into the room. Not sure yet how it will work putting the foil on top of the reed fencing. I bought a couple of cans of spray adhesive and thought I would spray as I roll out the foil. I just hope there is no wind.
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> So now it's time to have a little supper and collapse into bed.
>
> The Making of Papercrete DVD now available on Amazon.com
> http://www.amazon.com/Making-Papercrete-Judith-Williams/dp/B0040ZNE9A/ref=sr_1_1?ie=UTF8&s=dvd&qid=1283998627&sr=8-1
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> Follow progress on the new project at http://www.papercretebyjudith.com/blog
>
> More papercrete info at http://squidoo.com/papercretebyjudith
>