[GSBN] Straw bale lambda

[Graeme North]

I stand guilty of digital muddling - thanks for noticing.

cheers

Graeme
Graeme North Architects
49 Matthew Road
RD1
Warkworth
tel/fax +64 (0)9 4259305

graeme at ecodesign.co.nz
www.ecodesign.co.nz


On 17/06/2009, at 3:55 AM, Derek Roff wrote:

> Hi, André,
>
> In my edition of Bruce's book, on page 185, Footnote A, the general  
> conversion factor is given as 5.678, for converting between metric  
> and "Murrican" U-values.  Inversely, the conversion factor for R- 
> values is given as 0.1761.  (Since 5.678 and 0.1761 are inverses,  
> either of these numbers is sufficient for converting both U-values  
> and R-values in both directions, if you set up the equation  
> properly).  Bruce's conversion factor is in agreement (of course)  
> with several web sources, including Wikipedia on R-value: <http:// 
> en.wikipedia.org/wiki/R-value_(insulation)> (Click on item 1  
> "Units") in the pages Contents.)
>
> On page 187, Bruce's book gives an R-value of 1.45 per inch for  
> strawbale.  It goes on to say that the thermal resistivity was  
> found to be higher for bales stacked on edge than flat.  It doesn't  
> say which orientation the 1.45 figure refers to.  Using the R-value  
> conversion constant of 0.1761 from page 185, I set up the equation  
> like this:
>
> (Murrican R-value) 1.45/inch x 0.1761 (Murrican R-value to metric  
> conversion factor) x 39.37 (inches to meters) = 10.05 (metric R- 
> value per meter)
>
> 1.45 x 0.1761 x 39.37 = 10.05
>
> That seems to confirm Rob Tom's calculation.  Not that I ever  
> doubted it.
>
> Derek
>
> PS.  I wonder if Graeme North might have transposed two digits in  
> his message.  5.678 rounds nicely to 5.68, which is in agreement  
> with all the sources that I looked at.  "5.86" looks like it might  
> be the same number with the last two digits transposed.
>
>
> --On Monday, June 15, 2009 8:22 PM +0200  
> contact at lamaisonenpaille.com wrote:
>
>> Hello,
>>
>> For the purpose of publishing Bruce Kings book "Design of SB
>> Buildings" in french I would appreciate someone from this list
>> confirming Rob Tom's conversion below (for page 187):
>>> A thermal resistivity of 1.45 ft2*hr*degF/Btu*inch (Murrican)
>>> converts to 10.05 m2*degC/W*m (SIU).
>>>
>>> The thermal conductivity, or lambda value = 1 / thermal resistivity
>>> = 1 / 10.05 m2*degC/W*m
>>> = 0.0994 W/mK lambda (?)
>>
>> Thanks,
>>
>> André de Bouter
>> La Maison en Paille
>> www.lamaisonenpaille.com
>> _______________________________________________
>> GSBN mailing list
>> GSBN at greenbuilder.com
>> http://greenbuilder.com/mailman/listinfo/GSBN
>
>
>
> Derek Roff
> Language Learning Center
> Ortega Hall 129, MSC03-2100
> University of New Mexico
> Albuquerque, NM 87131-0001
> 505/277-7368, fax 505/277-3885
> Internet: derek at unm.edu
>
> _______________________________________________
> GSBN mailing list
> GSBN at greenbuilder.com
> http://greenbuilder.com/mailman/listinfo/GSBN

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sustainablesources.com/pipermail/gsbn/attachments/20090617/9a1519bd/attachment.htm>