[GSBN] [nbne] R-value of compressed straw panels

[Bruce King]

I've been following Stramit for a long time.  I can't put my fingers on hard numbers, but am extremely skeptical of the R-3+ per inch claim.  I'd expect something more like R-1.2 per inch, or so.

Anyone else have insight or new data?

Thanks,

Bruce King

(415) 987-7271
Skype: brucekingokok
Twitter: @brucekinggreen 
http://www.housetalkgreen.com
http://bruce-king.com/





On Apr 21, 2013, at 7:12 PM, ejgeorge at riseup.net wrote:

> Hey again all. This question came up on the NBNE list from Tristan Roberts of BuildingGreen. Robert Riversong's response is included below Tristan's post, but I thought someone over here might also have more information on the purported Stramit lab test.
> 
> ----- Forwarded message from tristan at buildinggreen.com -----
> 
> 
> Hi,
> 
> Does anyone have insight into the R-value of compressed straw panels such as Stramit (currently produced in Texas) or Agriboard (no longer being produced)?
> 
> Stramit USA claims R-3.03/inch, and I have even seen press releases claiming R-3.35. However, the company can't produce a lab test to prove this to me, and there is history of R-value inflation in compressed straw, as this old EBN article talks about:
> 
> http://www.buildinggreen.com/auth/article.cfm/1998/1/1/Agriboard-s-Inflated-R-value-Claims/
> 
> I supposed there might be less convective loops in a compressed straw panel compared with a bale, but intuitively it's hard for me to picture how compressed straw has higher R-value.
> 
> It's probably a longshot, but I wondered if anyone has any insight (or maybe you know someone who might). Also, if you have any recent experience with Stramit, I'd like to talk with you.
> 
> thanks!
> 
> Tristan
> 
> 
> ____________
> Tristan Roberts
> Editorial Director
> BuildingGreen, Inc.
> http://www.BuildingGreen.com
> http://www.LEEDuser.com
> 
> (802) 257-7300 x121
> tristan at buildinggreen.com
> 
> -----------end forwarded message -----------
> 
> Robert's reply:
> 
> Loose fibrous materials often increase in R-value per inch with increased density - up to a point of diminishing returns - and I have no reason to doubt that compressed straw would be more insulative than straw bales.
> 
> Loose-fill fiberglass, for instance, is about R-2.5/inch, while fiberglass batts, which used to be about R-3.14/inch for standard R-11 batts, were increased to R-13 (3.7/inch) in "high-density batts", and semi-rigid fiberglass board as well as dense-pack Spider is about R-4/inch.
> 
> Similarly, loose fill cellulose is about R-3.4/inch at 1.4 pcf density, while dense-pack cellulose at 3+ pcf can be as much as R-3.8/inch.
> 
> But the density range that Stramit specs of 15.6-40.5 pcf puts it at about the same density range as solid wood, which is about R-1.25/inch. So I also question their claim of R-3.35/inch.
> 
> 
> 
> _______________________________________________
> GSBN mailing list
> GSBN at sustainablesources.com
> http://sustainablesources.com/mailman/listinfo.cgi/GSBN

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sustainablesources.com/pipermail/gsbn/attachments/20130421/4eec8bdc/attachment.htm>