[Strawbale] Strawbale Digest, Vol 40, Issue 9

Peter van Balen peter at tentotwo...
Wed Mar 18 19:33:05 CET 2009

I tend to agree with Dirk; that's why I calculated our house with the  
0,052 and 0,08 figures (as 40% is 'on edge' and 60% is 'flat')

> From: Dirk Scharmer- Architekturb?ro WAND4 <info at wand4...>
> Herbert, Andr?, Peter, ...
> I sent our last test results directly to Andr?. Herbert, I think you
> know the Austrian activities very well but let me speak for the German
> results and approvals:
> In Germany we did about 15 lambda-Value tests (thermal conductivity)
> according to EN 12667 since Mai 2003 (Attention! Herbert used
> accidentally the term 'R-Value' which is not the conductivity but the
> thermal resistance). We found a variety of values mainly depending on
> density, humidity and fibre orientation and probably fibre length  
> (type
> of harvester-thresher).
> Our best value was lambda 10,dry= 0,038 W/mK and our worst
> lambda10,23/80=0,082 W/mK. We found conversion factors from dry to wet
> between 1,07 to 1,2.
> We tested densities (dry) from 80/ to 116 kg/m3. We tested wheat and  
> rye.
> The official approved "Baustrohballen" can be calculated perpendicular
> to the fibre direction with lambda=0,052 W/mK (max. lambda dry=0,044
> W/mK+ 20% addition) and in fibre direction with lambda=0,08 W/mK (max.
> lambda dry=0,067 W/mK + 20% addition).
> Our current goal is not the maximum optimization of the lambda value  
> but
> the maximum optimization of the usability of local bales which are
> produced under normal agriculture conditions. For this it is more
> important to provide a calculation lambda value which covers the  
> variety
> of occuring lambda values to avoid failing of some bale charges (the
> distributor has to sign for the compliance of the properties).
> I think we should have a session at the ESBG in Belgium in August to
> this topic where we first present the current knowledge and the  
> country
> results to each other. After heaving heard the international results  
> and
> approaches we should of course discuss, e.g. lambda value  
> optimization,
> fibre direction, humidity, density and strategy, ...
> And to avoid another confusion: "Baustrohballen" are of course  
> "normal"
> straw bales and I think there is not a difference to normal austrian
> bales (of course we saw differences in past between bales from  
> different
> countries depending on the baler, on the acre, on the type of corn, on
> the type of cultivation,.... "Baustrohballen" are produced directly on
> the fields with normal balers (common ones in Germany: Welger ap 53,63
> and 630 to 830, or different types of John Deere or Claas,...)
> I'm keen to see the new Austrian test reports and how you managed to
> optimize the lambda Value (pressing method?) and how you want to  
> ensure
> the thermal quality while the production of the bales.
> And last but not least: Straw is not equal to straw, testing  
> procedures
> not equal to testing procedures and countries approaches not equal  
> to ...
> And please have in Mind: Most of the international R-Value-Tests (now
> I'm speaking about the resistance) shows much higher recalculated
> lambda-Values >0,06 W/mk as the Germans and Austrians are talking  
> about,
> on more reason for me, not to count on the best values.
> Dirk
> Fachverband Strohballenbau Deutschland e.V.
> c/o Dirk Scharmer
> In de Masch 6
> D-21394 Suedergellersen
> Tel. 0049 4131- 727804
> Fax. 0049 4131- 727805
> Internet: www.fasba.de
> Email: ds at fasba...

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