NOTE: I have moved this post over from
3/4" foam board insulation help, as it is a better fit for this thread.
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Quote:
Originally Posted by Exeric
...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...
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Exeric,
Being an earthling myself, I can certainly understand your preference for earthly solutions.
However, it is very interesting to note that not everyone is so smug about insulation.
For instance, in the UK, they have taken the lessons of NASA more seriously than here in the Motherland.
I came across
THIS interesting Multi Layer Insulation that is for sale right now.
It is tested and sold as having an R rating of 2.71.
You gotta understand that this is 2.71 metric, which is not the same as our USA R-value.
I'm sure that someone smarter than myself could convert in a more straight forward way than me, but here's how I do it:
2.71 watts/m2-K is the R-value
If you invert that value you get .369 m2-K/watt which is the U-value in metric.
HERE is an amazingly useful converter for converting most things to and from metric.
Looking at the yellow ellipse on the left is the closest value I can find to .369 m2-K/watt.
Looking at the yellow ellipse on the right, you see the R-value equivalent, which is R-15.30
That is a whole different ball game, no?
But if you look at the detailed specs on the bottom of
the next page you will find this chart:
You see that this 19-layer wonder stuff is 13.5 mm thick, which works out to:
13.5mm/25.4mm per inch = .55 inches
So in reality, the material actually has the following R-value:
15.3/.55 =
R27.7 per inch.
That is the R-value in the UK, not in space, by the way.
So, you may not like this product, but you can't deny the principle.
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I just found a much simpler way to convert R-value from Metric to Imperial:
1 R value = 0.17611 m[sup]2[/sup] kelvins/watt
So, you take what ever metric R value, like 2.71 from the illustration above, and devide it by 0.17611
So 2.71/0.17611 = 15.39 (even more than I came up with)
But you still need to level it out on a per inch basis, so
15.39/.55 =
27.98 per inch
-AC