Cob: Re: Re: Thermal Mass and R-values

[alexander neumann]

Hey Mike and all,

> The equation that was developed for computing the thermal conductivity of
> clay-straw mixes was derived by looking at data over a wide range of mix
> densities.  There was over a 10:1 difference between extremes, so there
is
> obviously something worth talking about there. 

The Values I quoted where those generally accepted, they´re naturally
something like the lowest common level, if you believe you can get better
values, you got to prove it to the building official (in germany).

>I will put
> forth that the Minke straw-clay equation is not relevant to that layer
> (unless it is made of straw and clay!) and that people should not be
> discouraged from trying "natural" insulation alternatives on the basis of
> that equation.

The values I gave did not come from Minke, although he´d probably give
similar ones, but he was the one who said that even if you try to make a
mix with a very low density, you most often get higher densities around
600kg/m³.

I do not think it´s all hopeless, I just do not believe in reasonable
insulation values of clay mixes that are strong enough to hold itself up. 

> 
> Fiberglass and cellulose have enough drawbacks to warrant considering
> alternatives, even if you get a thicker wall as a result.

I still can´t see any better product than cellulose in energy efficiency.
Well, maybe norwegian sweaters instead of T-shirts...


Yours, Alex

P.S.: John, I´m afraid the Book I mentioned is not yet translated, as it is
relatively new and specifically german. It was edited  by a NGO called
"Dachverband Lehm e.V.", publisher is "Vieweg", http://www.vieweg.de .