Isolation in corks recovered?

[Obamot]

Well take Soudal or Sika ...

I don't know what to say, I took mine from Leroy-Merlin, and from Jumbo, in my corner, and it burns po ...
http://www.jumbo.ch/fr/home.html

In addition I had read this directive, so I am sure I did not dream, since I had copied it to a landlord who wanted to do work, and for whom it was a sine qua non condition. I also took the test in his presence and he is a physicist at Cern ...

I will ask her for a copy.

On the other hand Chatelot, carried away by enthusiasm you often tell us things in this forum, which prove to be inaccurate (as with cork 7x less thermally conductive than wood ...), so hey you say it burns, that you compared the old and the new, I don't mind! But at 3am, how do you find this and be sure that it is what you think ... Hmm, you should (re) check my dear. I am sure I am not mistaken.

Come on goodt by night

[chatelot16]

simply because there is in the room where I am a hole that I plugged not long ago, with an old bomb and a recent bomb

the old bomb made of hard and yellow foam ... the recent soft white foam ... and the 2 burn well

that you bought from a certain supplier of foam that does not burn does not prove that this is necessarily the case of everything that is sold in France

it deserves to inquire ... if we find inexpensive non-combustible foam it can be used

[chatelot16]

I never said that the wood was as good insulator as the cork ... I just said that if it was to serve as a wedge fixing a spacing therefore of fairly small section, wood and as good as cork

and your figures confirm it: if the surface of the shims is 1000 times smaller than the air surface the passage of heat through the wooden shims is negligible

[Obamot]

the old bomb made of hard and yellow foam ... the recent soft white foam ... and the 2 burn well

It is not the foam that must be tried to burn, but the polymerized substrate (after the reaction phase, once the expansion of the foam is complete and solidified).

Otherwise, it makes no sense, of course when it comes out of the nozzle it burns, if only because of the propellant ... !!!

As for the rest: 2nd law of thermodynamics!

If you have a narrower water pipe with the same flow rate, it will not change anything, except that it will increase the pressure. So if you have heat exchanges that can be done, if you reduce the surface you will increase the condensation, where is the benefit in your reasoning? Again, impossible to say if we did not make a diagnosis on the spot.

So instead of improving the coef, you would like to focus the thermal bridge on a small area.

Always starting from the same reasoning as yours, if it is 7x less, the cork would be 7'000x weaker with a less surface then?

When it comes to removing an intense thermal bridge, I would take!

And we always come back to the same point, it depends on the case.

I was confronted with thermal bridges so intense, that nothing helped, in particular a house located at 1'000m in an undergrowth, with almost no sunshine in winter, since located on the slope of a ridge ( therefore hidden from the sun until late in the day). Impossibility to make ITE, because this other owner wanted to keep the "cachet" of his stone walls 40 cm thick.

Believe me that if at the time I had thought of this solution, I would have applied it! Because there was not yet polyurethane foam or acrylic paint shielding against humidity.

[chatelot16]

the old bomb made of hard and yellow foam ... the recent soft white foam ... and the 2 burn well

It is not the foam that must be tried to burn, but the polymerized substrate (after the reaction phase, once the expansion of the foam is complete and solidified).

Otherwise, it makes no sense, of course when it comes out of the nozzle it burns, if only because of the propellant ... !!

I did not try what came out of the bomb: I took pieces exceeding what was plugged a few months ago

[Ahmed]

Could you clarify, oh Bamot, the distinction you make in this sentence:

No, it is not an air gap but an air confinement ...

Is it the narrow width that would prevent convective phenomena?

[chatelot16]

we find tables where there is the thermal resistance of an air space: in small thickness (a few mm) the thermal resistance is proportional to the thickness as if the air were a solid insulating material ... strong thickness the thermal resistance is completely independent of the thickness: it is only the convection that counts: whether the thickness is 10cm or 1m does not change anything

[Obamot]

Yes the use of "air blade"(which is not mine) applies to several things:

- ventilated air space;
- non-ventilated air space;
- wall insulation air space;
- air space under the roof;
etc

Except I don't like the term "non-ventilated"Because it doesn't mean "hermetic". Reason why I prefer to say "Confined air" (assistant of an airtight vapor brake ... as soon as necessary)

I also do not like to use this term, following our rivers debates in this forum, on the air spaces between the shutters and the windows, or between curtains and windows, very insulating for some VS peanut effect for others (my position is known, it isolates peanuts if we take into account the effect convection that prevents correct temperature measurements: I dare not even talk about heat exchanges resulting from air circulation: we should all know that air circulation when there is a convection phenomenon associated with a significant ∆ °, accelerates heat exchange by a draw effect, which would be equivalent in volume to leaving a door wide open! Reason why it is necessary to confine!)

So we come to the phenomenon of convection: yes indeed, there will always be this problem and Chatelot has responded better (and immediately correctly, unlike me, who did not address this problem) when it comes to saying that '' there is an optimum thickness of air space to find.

use air knives to insulate, it can work but you just need the right thickness; if the air layer is too thick it will convection too much and it will not isolate

What would it be? 5/8 inch according to a Canadian study (which makes between 1,2 and 1,5 cm) for the air located between airtight double glazing (ideally 1,6 cm) but in Canada it curdles more than here! However, this is an average calculated at best between diurnal VS nocturnal cycle for an ideal in a given geographical area amha (ours are clearly between 1,6 and 2cm).

In this case, it will be a little more. First, because the confined air is not subjected to solar radiation and the temperature of "the whole system" fluctuates at the same time (diurnal cycle VS night cycle). Finally, unlike double glazing, we do not have extreme temperatures on both sides (very cold exterior glazing VS tempered interior glazing), there we have a wooden wall which greatly slows down the effect (lowering the coef "U") if it is 2cm, there is only one inch of air space left. Finally, I recommended painting the wall with an acrylic-latex emulsion (weather shield), precisely to reduce the surface exchange coefficient and guarantee waterproofing. We can still improve, with a sheet of mylar ...

So an inch seems fine to me, even if it's a high limit relative to double glazing. And indeed, it is a compromise, but a case where the goal is to get by with recycling materials.

But be careful, no metal in this mess, because suddenly the convection could take a boost (and even wood is not recommended, due to the heat transfer between two walls, via contact points => reduced to a minimum with cork). But that's just my humble opinion (and feedback from critical cases).

[Obamot]

[Edit] I just went to check the caliper, the air gap is around 15 mm in my double glazing (but it is argon and not air).

[chatelot16]

I looked for numbers a long time ago, and I found that
http://forums.futura-sciences.com/habit ... -dair.html

we see that the resistance of an air knife depends not only on the thickness but also on the position

if the blade is vertical the resistance is capped at 0,18 (m².K) / W at 25mm, finally it is already 0,17 at 15mm so we can say that it already capped at 15mm

with a horizontal blade it depends on the direction of the heat: if the blade is under the hot face, the insulation increases well at all thicknesses because there is a stratification in my right direction

if the hot side is down, convection is even stronger than with a vertical blade