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Re: GSBN:Re Thermal Properties of Straw Bale Walls



Hello Nehemiah,

Is there not a different R-value per inch for bales on-edge and laid-flat?
My understanding is that the Oak Ridge National Lab test showed this.  The
result, in California, being that walls with 3-string bales on-edge (15"
thick) and laid-flat (23" thick) are considered by the California Energy
Commission to have the same R-value of R-30.  If I am correct that would
yield an R-value per inch as follows:

On-edge:  R-2 per inch
Laid-flat:  R-1.3 per inch

I know there has been discussion about straw orientation, which in theory
explains the higher unit R-value for a bale on-edge, and how not all baling
machines bale straw with a clear orientation.  (I can tell you that the
straw orientation of the bales we're making manually in Pakistan have no
orientation.  We just grab big balls of straw and stuff them into the
compression mold!)

I also wonder if there is any appreciable difference from one grain to
another.

Any sage thoughts?

Martin Hammer



> John,
>
> For all intents and purposes, the value per inch is constant once you get
> to the size of a bale.  It might not be if you were dramatically
> down-sizing from the test specimens, but going larger, relative uniformity
> is a safe assumption.  What we found in the ORNL test was about 1.47 per
> inch (3.82/m Aussie).  Since the render adds mass w/o any significant
> insulation, the 36" bale wall you are considering should be about R-53
> (~R-9.4 Aussie).
> Hope this helps.
>
> Nehemiah Stone
> stoneandstraw@...
>
>
>
>> [Original Message]
>> From: John Glassford jacksflat@...
>> To: GSBN GSBN@...
>> Date: 5/17/2007 1:40:33 PM
>> Subject: GSBN:Re Thermal Properties of Straw Bale Walls
>>
>> G ' day Balers
>>
>> Can any of you help with thermal properties of jumbo bales?
>>
>> I have Nehmiah Stone's work and was wondering if I can extrapulate
>> from them inch by inch?
>>
>> If so what value would you give a 900mm or 36" straw bale wall plus
>> 100mm or 4" of render?
>>
>> We are about to build a community centre in Sydney for the Fairfield
>> City Council from jumbo balaes 2.4m x 900mm x 600mm.   Bales 6 high or
>> a wall of 3.8 m finished including top and bottom plates.  The
>> building will be used for community events in the heart of Sydney or
>> it's geographical centre.  Will be good for straw bale. Bales on the
>> flat i.e. 900mm.
>>
>> Any help will be appreciated thanks.
>>
>> Aussie R values are around R7-9 for straw bales so multiply by 5.6 for
>> USA R values, I think.
>>
>> Kind regards
>> John Glassford
>> Huff 'n' Puff Constructions
>> <a  target="_blank" href="http://www.glassford.com.au/";>http://www.glassford.com.au/</a>
>> Mount Kilimanjaro Climb 28/8/07
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>>
>> Yours in Rotary
>> John Glassford
>> International Services Director
>> Rotary Club of Coolamon District 9700
>> New South Wales, Australia
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