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<TITLE>Re: [GSBN] [nbne] R-value of compressed straw panels</TITLE>
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<FONT FACE="Arial"><SPAN STYLE='font-size:9pt'>Bruce, what about Oryzatech’s compressed rice straw block ‘StakBlock’? I think you are very familiar with the upstart product, and that the blocks are at least as dense as Stramit panels. On Oryzatech’s website (www.oryzatech.com) they claim: “<FONT COLOR="#323232"><B><I>Highly insulated</I></B>: More than three times the value of an insulated 2X6 stud walls”.<BR>
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>From that 3 x R19 divided by 12” (block thickness) = R4.75 per inch<BR>
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I think we have discussed this, and we both find it impossible to believe this claim (though we both see StakBlock as a great product with huge promise.)<BR>
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Martin<BR>
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On 4/21/13 9:42 PM, "Bruce King" <<a href="bruce@ecobuildnetwork.org">bruce@ecobuildnetwork.org</a>> wrote:<BR>
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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.<BR>
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Anyone else have insight or new data?<BR>
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Thanks,<BR>
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Bruce King<BR>
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On Apr 21, 2013, at 7:12 PM, <a href="ejgeorge@riseup.net">ejgeorge@riseup.net</a> wrote:<BR>
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</FONT></SPAN><BLOCKQUOTE><SPAN STYLE='font-size:9pt'><FONT FACE="Arial">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.<BR>
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----- Forwarded message from <a href="tristan@buildinggreen.com">tristan@buildinggreen.com</a> -----<BR>
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Hi,<BR>
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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)?<BR>
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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:<BR>
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<a href="http://www.buildinggreen.com/auth/article.cfm/1998/1/1/Agriboard-s-Inflated-R-value-Claims/">http://www.buildinggreen.com/auth/article.cfm/1998/1/1/Agriboard-s-Inflated-R-value-Claims/</a><BR>
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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.<BR>
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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.<BR>
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thanks!<BR>
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Tristan<BR>
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____________<BR>
Tristan Roberts<BR>
Editorial Director<BR>
BuildingGreen, Inc.<BR>
<a href="http://www.BuildingGreen.com">http://www.BuildingGreen.com</a><BR>
<a href="http://www.LEEDuser.com">http://www.LEEDuser.com</a><BR>
<BR>
(802) 257-7300 x121<BR>
<a href="tristan@buildinggreen.com">tristan@buildinggreen.com</a><BR>
<BR>
-----------end forwarded message -----------<BR>
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Robert's reply:<BR>
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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.<BR>
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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.<BR>
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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.<BR>
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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.<BR>
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