Supper Insulation ??

[markfxy]

that stuff is a bugger to drill through it wraps round your drill bit and you can't get the dam thing😕 out it is very efficient though

 

[Ric2013]

So how do you joint it properly? You'd have to unpeel and stick each layer separately otherwise you're creating a cold bridge at each joint and you may as well just use newspaper. Otherwise I suppose it works.

One comment I would make is that the claim is often made about certain types of reflective insulation that they work in spacesuits. Well, of course they do. No atmosphere = no convection. No planet to stand on = no conduction. So heat is only transferred by radiation and conduction. Foil lined bubblewrap would work well in a spacesuit as it would only lose a little heat through the silvery surface. Back on earth, it is reasonably useless.

I'm totally not saying your stuff is the same as foil lined bubblewrap and, in fact, I have toyed with using it to refurbish my own extension, but I never got my head around how to maintain the thermal envelope at junctions as this would have been important and difficult in this kind of retrofit situation. Let us know how you got on. I for one am interested in how you get around difficulties.

 

[Chuck]

So how do you joint it properly? You'd have to unpeel and stick each layer separately otherwise you're creating a cold bridge at each joint and you may as well just use newspaper.

MIs say to overlap the joins.

No atmosphere = no convection. No planet to stand on = no conduction. [...] Back on earth, it is reasonably useless.

Convective transfer between the foils is suppressed by the spacer. Transfer by conduction is negligible, the thermal conductivity of stationary air is negligible.

The thermal performance when correctly installed is excellent. The problem is that it's difficult to install correctly outside a laboratory.

The sample I played with a few years ago was also flamable to the point being downright scary. Modern stuff may be better. I certainly hope so.

 

[Ric2013]

MIs say to overlap the joins.

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.

Convective transfer between the foils is suppressed by the spacer. Transfer by conduction is negligible, the thermal conductivity of stationary air is negligible.

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

I hope you don't think I am having a dig at the OP's product. I was merely reflecting on the properties of multi-foil insulation, including the cheaper foiled bubblewrap type, and the difference between their performance in outer space and on planet earth. I knew someone who was convinced the bubblewrap kind that her landlord had fitted was 'brilliant as it works on spacesuits' and 'the best insulation ever' when my own experience was that it was very poor. Plus her house was always cold.

 

[OffshoreGas]

I used to find fitting PIR to be a real chew, then I bought one of these. Its an over priced carginv knife but it makes the job so quick/easy it pays for itself in one or two jobs.

 

[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...