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Re: [Strawbale]Re: Strawbale digest, Vol 1 #474 - 7 msgs

Tom -
That part of the Danish document is actually in English - luckily for you and me... (though I've got quite good at translating technical Danish over the last few months - not that I could pronounce it reliably, nor translate it the other way...)
So far as I can see, the use of bales on edge is pretty common in post-and-beam construction in northern Europe. Structurally, this is obviously OK, but I have doubts on the matter of fire resistance - the strings are not hidden inside the bale and so may be more readily melted by fire, allowing bale disintegration at an earlier stage. If anyone can raise the funds, I think the relevant fire tests should be commissioned from an appropriate body - I think I am right in saying that the fire tests carried out so far in Europe (German DIN EN 1363, Austrian OeNORM B3800, Danish DS1051) were all conducted using bales laid flat, so don't provide the info necessary for a bales-on-edge assembly. (No doubt someone will correct me if I am wrong - please!) 

Mark


fostertom@clara....uk wrote:


Great comment Mark. Bales on edge? Woof! sounds dodgy - do they do that?
Is the Danish stuff available in English?

Tom Foster B.Sc.(Architecture) AECB
Tom Foster Architecture





-----Original Message-----
From: strawbale-admin@amper....muni.cz
[mailto:strawbale-admin@amper....muni.cz] On Behalf Of Mark
Bigland-Pritchard // Low Energy Design
Sent: 08 January 2005 14:35
To: strawbale@amper....muni.cz
Subject: Re: [Strawbale]Re: Strawbale digest, Vol 1 #474 - 7 msgs

Dear all,
The low lambda results in Germany, Austria and Denmark are indeed based on official test procedures, and appear to be reliable. However, in these procedures, (i) the thickness of bale used is smaller than that for a wall assembly, and (ii) only very dry material is used. Hence, if
(a) there is any heat transfer effect which isn't proportional in its extent to the thickness of material, or (b) if moisture movement makes any difference, these tests will not be directly applicable for U-value calculation without some sort of adjustment factor. There is reason to believe that convective effects, including moisture transfer, do make some difference in a real-life wall assembly. This indeed appears to be the case when we look at the whole-wall U-value tests carried out by ORNL and by the Danish testing programme - both to variants of official test procedures in the countries concerned. These give significantly higher U-values than can be explained by the lambda values. There is some useful discussion of this 

in the Danish summary document:
Munch-Andersen, J & Møller Anderson, B (2004),   Halmhuse: Udformning og
materialeegenskaber, By og Byg resultater 033, Statens Byggeforskningsinstitut, Hørsholm, Denmark 
which is available online in .pdf format at the By og Byg website.
Realistically, I would not assume a U-value of less than 0.2 W/m2/K for a 2-string-bale wall laid flat. The results seem to me to suggest that you'd get much the same for the same bales laid on edge. (Though I personally have big doubts about on-edge bales for other reasons...) 

Mark


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