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Re: GSBN:Re Thermal Properties of Straw Bale Walls



John,

You could simply use my java script SB R-value calculator. (
<a  target="_blank" href="http://www.strobouw.nl/technical/sbrvalue.html";>http://www.strobouw.nl/technical/sbrvalue.html</a> this is the deep link
directly to the page, thus avoiding many clicks.)
It is primed with a not too conservative labda value of 0.08 but you
can insert your own favorite value. The calculator also gives some
notes on SB r-values. The calculator works both ways ie you can
determine how thick a SB wall should be to achieve a certain R-value or
given a certain thickness what the r-Value would be. It also takes an
interior and exterior earth plaster into account including the interior
and exterior air transition. In metric and imperial. You can also use
the calculator as a metric to imperial R value converter.

The R value of a SB wall is something of a holy grail for the SB
community it is difficult to give really hard values for. What we do
know is that taking good SB practice into account a labda value of 0.1
is rather pessimistic and 0.045 is very optimistic. Based on previous
discussions I expect that air convection within jumbo bales is even
more of an issue then normal 2-3 string bales this will be offset
though by the higher density of the jumbo bales.

Rene
On May 18, 2007, at 04:03, John Glassford wrote:

G ' day Nehemiah and Andrew et al

Many thanks for the replies and for your considered input.  It is very
much appreciated.

I am sure that there is much more work to be done in this area
especially with jumbo bales as they are naturally compacted a lot more
than the smaller bales.  Does that provide more or less insulation?
Many questions ahead of  us.

Kind regards John Glassford.
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