Cob: Cob Homes in Canada?

[Mark Piepkorn]

There's a good and long interview (25 pages) with Ianto Evans and Michael 
Smith that appeared in New Settler magazine waaay back in '96. In it (a 
smiling nod to Amanda here), Ianto says, "I personally don't think that 
unmodified cob is suitable for extremely cold areas, unless there is very 
reliable winter sun. It doesn't have particularly good insulation 
qualities. It has high thermal mass, so it works great as a passive solar 
building. But I wouldn't be building with it in Manitoba, or Fairbanks, or 
Chicago."

I could say much the same thing myself, but who'd want to listen to me? 
Depending on exactly what he's saying (under close scrutiny it's not 
perfectly clear, and the term "extremely cold areas" isn't defined), the 
one issue I might take is that in areas with extremely cold winters (I grew 
up in Minnesota), even reliable winter sun isn't in all likelihood going to 
eliminate the need for significant auxiliary heating well in excess of what 
would be needed if the mass were insulated. That absolutely includes 
solar-exposed south walls. Take advantage of the solar exposure with 
glazing to allow the sun to heat the interior, insulated mass. And use 
insulated shades like the ones at http://www.cozycurtains.com/ to prevent 
night heat loss.

Jumping techniques but not topics, that Earthship guy Michael Reynolds came 
out with a book in 2000 called "Comfort In Any Climate." Some years before, 
I had big problems with his Earthship series of books, especially the first 
one, for the sweeping generalizations it made about mass and 
earth-coupling. I was amused (and relieved) to read in this newer book, "In 
recent years we have recognized the fact that insulation can help keep 
temperature in a shelter... Insulation acts as a blockade for temperature - 
not allowing it to enter or pass through... [In bold type, it continues:] 
There is a major difference between mass and insulation... [Then, in 
italics:] An ideal wall would have both mass and insulation." (I still have 
problems with the broad, simplistic brush he uses with regard to 
earth-coupling, though.)

Now, don't be confused by materials that claim to be mass and insulation 
all in one package. When somebody says something about, say, cob, or 
sand-enhanced papercrete, as being both massive and insulative, while 
truthful, it's hooey. Every building material is massive to some degree, 
because every building material is convective to some degree. Conversely, 
every building material is insulative to some degree, because every 
building material slows thermal transfer to some degree. So if somebody 
says that a material both mass and insulation, what they're saying is that 
it's not particularly good at either.

A short, worthwhile read: "Thermal Mass and R-Value: Making Sense of a 
Confusing Issue"
http://www.buildinggreen.com/features/tm/thermal.cfm

Also interesting:
http://www.repp.org/discussion/greenbuilding/200101/msg00037.html