[Cob] Coblist Digest, Vol 9, Issue 74

[Janet Standeford]

Thank goodness Janet has come up with numbers on compression strength, 
which I'd love to have a spec sheet that comes from the lab.

Hi again,
All anyone needs to do is make the cob in 5 x 5 x 5 blocks. Five of them 
and take them to a Company that tests concrete for building sites. They 
cost $18 each. Go by alternative building code under adobe for this test.

As for R Value, check the following out and if your officials will not 
accept this email at face value, find the people that performed the 
energy test and they may give you a copy of their results. If anyone 
does this it would be nice if they "shared" on the list. This email can 
be traced back to an Arizona Building Official that I originally 
contacted. Start at the bottom to read it. I would be happy to forward 
the email to anyone that needs it.



-------- Original Message --------
Subject: 	Thermal Mass
Date: 	Mon, 10 Jan 2011 12:43:24 -0700
From: 	Rich Franz-Under <Rich.Franz-Under at dsd.pima.gov>
To: 	janet.standeford at gmail.com



Dear Janet,

Per our phone conversation regarding the thermal performance of mass
walls:

Using dynamic energy modeling it is possible to compare the energy
performance of mass wall and non-mass wall homes.  In the past, we have
worked with the University of Arizona, College of Architecture to have
this comparison done.  The result is sometimes called the equivelent
R-value. In our climate here in Tucson, a 20" adobe wall home, with
properly sized and shaded south facing windows, will have the energy
performance of a home with R-19 insulated walls.

I recommend that you work with a person familiar with dynamic energy
modeling using eQUEST, energy 10, or another dynamic energy modeling
software and present these results to your building department.  Section
404 of the International Energy Conservation Code, titled "Simulated
Performance Alternative"  allows for energy modeling to show that you
are meeting the minimum requirements of the code.

Hope this helps!


Rich

P Please consider whether it is necessary to print this email.

-----Original Message-----
From: Dr. Nader Chalfoun [mailto:chalfoun at email.arizona.edu]
Sent: Wednesday, February 25, 2009 8:13 AM
To: Rich Franz
Subject: Re: Rammed Earth R value and model energy code

Rich:

Thermal mass simulation in steady-state models like RESCheck or COMcheck
are modeled using the equivalent R-value that yeilds the same results as
a case simulated with a dynamic energy simulation model.

In our case, we simulated a 20" adobe in the dynamic model and tried to
match the same results by increasing the initial R-11 value of batt
insulation of a non-thermal mass residence.  That  equivalent R-value
was found to be R-19.

i.e. to account for the advantage of thermal mass in comcheck or
rescheck you can simulate a 18"-20" rammed earth wall as R-19.  To
accurately represents the results the thermal mass MUST have properly
sized south-facing windows per square feet of exposed thermal mass.
But this is another calculation.

Hope that helps,

Nader

--------------------------------------------
Nader V. Chalfoun, Ph.D. LEED AP
Professor of Architecture
Director: The House Energy Doctor Program
http://houseenergydoctor.arizona.edu
Coordinator: Graduate Program on "Design and Energy Conservation"
Coordinator: Environmental Education Ph.D. Minor Faculty on Global
Change Ph.D. Minor

Address:
University of Arizona
College of Architecture and Landscape Architecture 1040 N. Olive St.,
Tucson, AZ 85721, U.S.A.
Phone: (520)621-6751    Fax: (520)621-8700


Quoting Rich Franz<Rich.Franz at dsd.pima.gov>:

>  Hi Nader, Do you have access to any research on the R value of Rammed
>  Earth?  Thanks for your help!!
>
>  Rich
>
>  P Please consider whether it is necessary to print this email.
>
>
>  ________________________________
>
>  From: Daniel Ice
>  Sent: Tuesday, February 24, 2009 11:36 AM
>  To: Rich Franz
>  Subject: FW: model energy code
>
>
>
>
>
>
>
>  Dan Ice
>  Pima County
>  Assistant Building Official
>  (520) 740-6490
>
>  ________________________________
>
>  From: chris evans [mailto:evansarch at hotmail.com]
>  Sent: Tuesday, February 24, 2009 9:16 AM
>  To: Daniel Ice
>  Subject: model energy code
>
>
>
>  Daniel,
>  What value does the county accept for the insulation value of rammed
>  earth in REScheck energy code calculations? Is there an equivalent
>  R-value that is generally accepted?
>  Thank you,
>  Chris Evans