[Strawbale] SB R-values

Peter van Balen peter at tentotwo...
Wed Mar 18 12:55:08 CET 2009


Hi Herbert,
Sorry if I was wrong, but I was only forwarding (and translating) what  
Dirk Scharmer send me as late as May 10th, 2007.
Could you share with us the exact dimensions of your tested 'special'  
straw bales as well as saying whether they were tested posed 'flat' or  
'on edge'?
Thank you

> From: asbn <asbn at baubiologie...>
> Peter, this is wrong...
> These are not the official R-values for Germany. The official R- 
> Value for
> usual strawbales in Germany and Austria is 0,045 W/mK.
> These are the R-Values for "Baustrohballen", special bales tested  
> under
> special circumstances.
> And it is an old but wrong conclusion, that the worse R-values are  
> more
> realistic.
> We developed and tested those special strawbales for the building- 
> industry
> (for prefabricated walls and roofs) in 2008/2009 again in Austria  
> and had
> much better results in 2 different official testing-institutions:  
> 0,047 W/mK
> (inluding the 20% addition) ? although there is no test-paper  
> available yet
> (we are still optimizing...).
> The difference between "normal" strawbales and "Baustrohballen" is the
> testing-procedure according to EU-building-codes, but it is possible  
> to
> press those building-bales for prefabrication in a whole different  
> way, than
> Dirk did. It's all about pressing the bales in the best way.
> So we will have CE-certified "Baustrohballen" with nearly the same  
> good
> R-values as the R-values for normal strawbales in Austria and  
> Germany this
> summer.
> Best wishes, Herbert
> -- 
> asbn - austrian strawbale network
> ?sterreichisches Netzwerk f?r Strohballenbau
> 3720 Ravelsbach, Baierdorf 6
> Email: asbn at baubiologie...
> http://www.baubiologie.at
>> Hi Andr?,
>> Below the response from Dirk Scharmer of the German Straw Bale
>> Building association FASBA, when I asked him to comment on the 0,045
>> figure I had found on their site (http://www.downloads.fasba.de/Pb-lambda1.pdf
>> ). Dirk's basically saying that in Germany the official values to
>> calculate with are 0,08 (for bales flat) and 0,052 (for bales on  
>> edge)
>> and that these figures are 20% higher than the measured ones because
>> in Germany there's an obligation (for all natural fibre-based
>> insulation) to add 20% to compensate for the fact that the lambda  
>> test
>> are done on dry material whereas in the real world relative humidity
>> of 75-95% in the walls do mean that insulation values decrease. He
>> finishes with saying that these official 'calculation' values are not
>> as good as the Austrian ones, but more realistic (according to him).
>> Hope this helps.
>> Regards, Peter
>> PS: their values are valid for densities 90-110kg/m3

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