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

[Mark Bigland-Pritchard // Low Energy Design]

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 at 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
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>-----Original Message-----
>From: strawbale-admin at amper....muni.cz
>[mailto:strawbale-admin at amper....muni.cz] On Behalf Of Mark
>Bigland-Pritchard // Low Energy Design
>Sent: 08 January 2005 14:35
>To: strawbale at 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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