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

[martin hammer]

Bruce, what about Oryzatech¹s compressed rice straw block ŒStakBlock¹?  I
think you are very familiar with the upstart product, and that the blocks
are at least as dense as Stramit panels.  On Oryzatech¹s website
(www.oryzatech.com) they claim:  ³Highly insulated: More than three times
the value of an insulated 2X6 stud walls².

>From that 3 x R19 divided by 12² (block thickness) = R4.75 per inch

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.)

Martin


On 4/21/13 9:42 PM, "Bruce King" <bruce at ecobuildnetwork.org> wrote:

> 
> 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.
>> 
>> 
>> 
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