[Cob] Cob R Value

[Amanda Peck]

It gets a little complicated.   But I don't imagine that 24' cob wall has 
only the same insulating value as a single pane of glass, which is roughly 
R-1. It sounds a bit like there's a default value of 1 for anything not in 
her computer program.

But.....

People have been arguing about "thermal mass" vs. "R-value" for years.  What 
Ianto says in The Hand Sculpted House is that cob is great if you live in it 
all winter.  Might not be so great if you are going to use it one weekend a 
month in the winter, and it's on a north slope, etc. etc. etc.

How the house is designed counts a lot.  A whole lot.

I have friends who are thermal mass freaks, and I must say that their house 
works well--they have insulation in the roof, not the concrete walls buried 
partway into the ground, and not the dark-stained concrete floor agressive 
south exposure, rarely use backup heating for the house--as opposed to the 
biggish greenhouse a couple of hundred feet away.  Cob should be a better on 
straight R-value than concrete, because of the straw, but it's still mostly 
a thermal mass house.  (it's 25 years old, so don't get too exited about how 
horrible concrete is).

Might take a look at this site for some more discussion of the subject.

http://www.monolithic.com/plan_design/rfairy/

..............

Steve wrote:
Hi Cobbers,

We have an home energy consultant reviewing our cob house plans. She wants 
to know the R value of cob. I heard around 0.7/inch, but only anecdotally. 
Does anyone know of any tests or work done to come up with an accurate range 
for R? To contrast the consultant had heard the value was closer to R1 for a 
24" wall.

Thanks,

Steve