Cob: Thermal Values of Cob

[Louis]

Hi cw;
I dug into the archives again [using Google] and found this interesting 
post from 5 years ago--Louis


From: SIMON RANDELL <SARSR at cardiff.ac.uk>
Date: Thu, 26 Oct 1995 12:11:38 GMT
Subject: Re: The thermal insulation of cobs in mud

[snipped]

For anybody interested) I recently conducted a thermal heat transfer and 
thermography test on a cob cottage here in the UK (we have 40,000 
structures in the SW). The result: U'Value - 1.0 W/m2degC density - 1860 
kg/m3 test duration - 29 days Density obviously had a huge effect and so 
did the heating source. Moisture content unobtainable due to metals in the 
mix giving inaccurate reading. Anyway, not bad for 170 year old building!


At 10:30 PM 11/2/00 +0000, cw wrote:
>Hi
>Thankyou for returning R and U values. A figure of 0.25 per square inch.
>This means that cob is a poor insulater-about 2.5 times less than normel
>sheeps wool or glass wool. Cob walls are, however, usually thicker than
>orthodox wall so this probably evens it out.
>
>It is interesting to think in this way for a bit because 'scientists' and
>'engineers' think this way and it is useful to understand some of their
>language. My friend the structural engineer worked out a K value (Thermal
>Conductivity value) from this R value for cob to be 0.1.  Not so good. K
>ranges from 0.025 W/mK to 0.04 W/mK for normal insulation materials -the
>lower the better - ie the less conductive of heat the better! He also asked
>if there was a value for density (kg/m*3). The more values to work from the
>better
>
>On the subject of the eco village-we are updating our web site and I will
>announce the site through the list.
>
>Thank you
>
>Caoimhin
>Dublin, Ireland