[Cob] cob thermal mass

[Dean Sherwin]

At 03:00 PM 7/21/2011, Janet wrote:
>Be aware that if I mention the R value of cob I am talking about the
>effective R value of 19 per 20 inches: This was the result of an energy
>model done on a house in Arizona. Their building inspector passed the
>results on to me and my building officials accept those for my house. If
>anyone would like a copy of the letter, just let me know. This will be
>my signature from now on to satisfy Shannon.

that may very well be true for Arizona.  But it wouldn't be the case 
in a different climate.  Think for a moment about Alaska, where it 
could be freezing for days on end.  Thermal mass will not help, the 
effective R value will be the usual 2-4, since the walls are 
constantly giving out heat.  Or Miami where it's hot most of the 
time, tho it would be a bit better there since insulation is not as 
critical where cooling is called for as with heating, and the nights 
are a bit cooler. (still it would be unpleasantly hot by nightfall 
and would take all night to cool, which is why you often see people 
in India choosing to sleep outside their houses) Thermal mass damps 
down the process of heat transmission in and out, so that earth 
building is great where it's at home, in New Mexico say.  But if 
there are no temperature swings, then what is the mass going to store?
For most places in the country insulation is one of the most critical 
aspects of energy efficiency and sustainable building, as I understand it.

Dean Sherwin
LEED Accredited Professional
CONSTRUCTION COST MANAGEMENT
3, Cherry Street
PO Box 11
Media, PA 19063-0011
(610)892 8860
fax (610) 892 7862
costman at verizon.net