[Strawbale] SB R-values German tests

asbn asbn at baubiologie...
Wed Mar 18 11:07:57 CET 2009

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
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

Best wishes, Herbert
asbn - austrian strawbale network
Österreichisches Netzwerk für Strohballenbau
3720 Ravelsbach, Baierdorf 6
Email: asbn at baubiologie...

> Hi André,
> 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
> ======================================
> Laut der in Deutschland nun geltenden allgemeinen bauaufsichtlichen
> Zulassung Z-23.11-1595
> http://www.downloads.fasba.de/AbZ-Nr.-Z-23.11-1595.pdf gilt ein
> Lambda-Rechenwert Halmrichtung von 0,08 W/mK und quer zur Halmrichtung
> von
> 0,052 W/mK. Die jeweils tatsächlich gemessenen Werte liegen 20%
> niedriger,
> weil es in Deutschland einen Sicherheitsaufschlag für pflanzliche
> Dämmstoffe
> gibt (es wird im trockenen Zustand gemessen, in der Wand herrschen
> aber ja
> auch mal feuchtere Bedingungen von z.b. 75-95% relative Luftfeuchte, die
> eine tatsächliche Verschlechterung der Dämmwirkung zur Folge haben
> könnten).
> Unsere Untersuchungen zeigen ziemlich deutlich, dass die
> Wärmeleitfähigkeit
> in Halmrichtung wirklich höher ist (also die Ballen liegend schlechter
> dämmen)
> Die obigen Rechenwerte von 0,052 und 0,08 sind zwar nicht so günstig für
> uns, wie die österreichischen sind aber meines Erachtens realistischer.
> Soweit erstmal?
> Gruss
> Dirk Scharmer
> Fachverband Strohballenbau Deutschland e.V.
> Auf der Ruebekuhle 10
> D- 21335 Lueneburg
> Tel. 00 49 4131- 2278649
> Fax. 00 49 4131- 2278648
> Internet: www.fasba.de
> ====================================
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