Supper Insulation ??

[Chuck]

So at each joint you have a piece of foil on the warm side in contact with a piece of foil on the cold side? Makes no sense.

The metal foil is extremely thin so the in-plane conductance is negligible.

But you still have convective transfer on the outside surface of the insulative layer.

The outer surface is at the same temperature as the 'external' air, hence no convection, because there is neglible heat transfer across the gap between the foils. (If you have a good conductor in series with a bad conductor the combination is a bad conductor.)

The theory underlying this stuff (physics) is sound but it takes more than that to make it a good choice in practical applications.

 

[OffshoreGas]

The metal foil is extremely thin so the in-plane conductance is negligible.



The outer surface is at the same temperature as the 'external' air, hence no convection, because there is neglible heat transfer across the gap between the foils. (If you have a good conductor in series with a bad conductor the combination is a bad conductor.)

The theory underlying this stuff (physics) is sound but it takes more than that to make it a good choice in practical applications.

The fibre insulation between the two foil sheets relies on air to act as an insulator. As soon as you compress it you’ve massively reduced the U value of the material.

 

[Ben-gee]

This is my issue with it too. When you staple it to the timber frame it is compressed to almost nothing and hence no good.

However the alternative of celotex between timbers also has this property at the timber...