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RE: GSBN:Tech points re: tests



I agree, not surprisingly, with Rene
The 0.04 value is too good to be true, and is equal to typical batt
insulations.
On the other hand 0.1 is the value for good cedar -- I think SB are
better than solid cedar (18" of which gets you R25).
In general a value of maybe 0.06 to 0.08 (R32 to 42 for 18" bale)
depending on density would be reasonable for very well installed bales,
and 0.08 to .1 for some gaps and excessively fluffy bales.

John Straube
School of Architecture and Dept of Civil Engineering
University of Waterloo
Waterloo, Canada
http://www.civil.uwaterloo.ca/beg


-----Original Message-----
From: GSBN [mailto:GSBN@...] On Behalf Of
rene.dalmeijer
Sent: April 21, 2004 17:58
To: GSBN
Subject: Re: GSBN:Tech points re: tests


Chris,

At 09:59 PM 4/21/04, you wrote:
>"Thermal conductivity was measured between Lambda (I havenot found the 
>greek symbol in the mail editor)  and from that resulted a Lambda D 
>(23/50) =  (building practical calculation value for 23#161#C and 50% 
>constant air humidity). "

This is a no brainer.

The measured thermal conduction coefficient ranges between 0,0395- 
0,041W/mK resulting in a practical calculation value of 0,046 W/mK This
for 
23 Celsius and 50% rel humidity

Lamda value conversion creates something quite awful unit wise if you go

imperial:

  1 Btu.in/sq ft.hr.F= 0.144229 W/mK Therefore

0.046 W/mK = 0.319 Btu.in/sq ft.hr.F

ie this equates to a 2 string bale wall with stucco having an R Value

of 9.36 m^2K/W = 53.15 sq ft.hr.F/Btu (oops found a units mistake on my 
webpage)

I regard this as a highly optimistic value and regard it with quite a
bit 
of hesitation for general use. My personal calculation value for Lambda
is 
0.1 W/mK. What the presented value effectively means is that straw
performs 
almost on par with true insulation materials like rockwool which is
rated 
at around 0.035-0.040 depending on density and type.



Rene Dalmeijer