Insulation: insulate with straw panels!

[bham]

[...] For the record, and to compare with expanded polystyrene, therefore the least efficient in thermal insulation, 40mm of polystyrene exp. have an R = 0,66 m2K / W. [...]

Huh? It's a bit the opposite and the figures you give are very bizarre .....

The opposite of what lumberjack and why my numbers are weird ???

[Woodcutter]

[...] For the record, and to compare with expanded polystyrene, therefore the least efficient in thermal insulation, 40mm of polystyrene exp. have an R = 0,66 m2K / W. [...]

Huh? It's a bit the opposite and the figures you give are very bizarre .....

The opposite of what lumberjack and why my numbers are weird ???

Expanded polystyrene is (unfortunately?) One of the most efficient insulators for winter and 40 mm of expanded polystyrene provide thermal resistance R = 0.04 / 0.035 = 1.14 and not 0.66 ...

[bham]

[...] For the record, and to compare with expanded polystyrene, therefore the least efficient in thermal insulation, 40mm of polystyrene exp. have an R = 0,66 m2K / W. [...]

Huh? It's a bit the opposite and the figures you give are very bizarre .....

The opposite of what lumberjack and why my numbers are weird ???

Expanded polystyrene is (unfortunately?) One of the most efficient insulators for winter and 40 mm of expanded polystyrene provide thermal resistance R = 0.04 / 0.035 = 1.14 and not 0.66 ...

To explain myself, by saying "therefore the least efficient in thermal insulation", I meant the least efficient of the 2 types of polystyrene, I admit that I lacked precision.
For the R, well seen lumberjack, I had made a calculation on the calculator of house ideas to quickly determine the R according to the lambda and the thickness, unfortunately it does not work as I thought and the value is erroneous; so in effect, with a lambda of 0.039 (house ideas value) and 40mm thick, expanded polystyrene has a thermal resistance of 1.02 m2K / W.

So to compare it to a straw panel thick 58 mm, with R value either = 0,72m2K / W (cd2e site) or = 0.56 m2K / W (batiproduct site), to have the same Rth with expanded polystyrene, you need:
Rth x Lambda = thickness
is :
1 ° - 0,72 x 0,039 = 0,028 m or 28 mm of expanded polystyrene
2 ° - 0,56 x 0.039 = 0,021 m or 21 mm of expanded polystyrene

So it's even worse than what I said, thermally speaking of course.

[jonule]

and as bucheron reminds us, the straw panel does not have the same thermal protection in summer as polystyrene.

[bham]

and as bucheron reminds us, the straw panel does not have the same thermal protection in summer as polystyrene.

Of course, I am jonule, I am rather pro-straw but in the matter it would be necessary to compare for example a panel of wood wool and a panel of straw; I tend to think that the straw panel offers good thermal insulation in summer so a good phase shift because of its density.
But its price, for a very cheap material at the base, is prohibitive for me when it is not as versatile in insulation as is wood wool. Let me explain :
If you take wood wool, also expensive despite a cheap base material, it displays a versatility in insulation, ie it insulates both cold and hot, we can say that the price is almost justified by this versatility.

This straw panel is in itself a very good idea but its implementation, by compression (wood wool also for that matter), has the effect of crushing the straw fibers and the air that they contain, thus the advantage of straw in terms of thermal insulation.
I have at home a piece of straw panel cut in slices and we can see that it gives a very dense material, necessary for the constitution of a rigid partition but less good for insulation.
If you want I send you a photo.
So surfing the wave of natural materials is a good thing but you have to know what you are saying because praising the merits of a product that does not keep its promises (at least those of organic / ecological sellers) in terms of risk insulation to discredit natural insulating materials.

[Woodcutter]

[...] So it's even worse than what I said, thermally speaking of course.

Yes !
And this is the big problem, moreover, because as long as people persist in seeing only the lambda of polystyrene, it is obvious that we cannot find a better performance, on this single criterion ...

Finally, and fortunately for other products, we do not ask that to an insulator (or else it means having a very short view ...! ).

Regarding the qualities of natural products, you must always always know what we are talking about and in this matter, we unfortunately find everything and anything on the Net ...

[greg33]

I allow myself to add a link to my blog: http://www.lamaisondurable.com/2008/02/ ... nce-t.html

[greg33]

Another link to http://www.lamaisondurable.com/2011/05/ ... %A9e.html/