[Cob] Straw bales vs ?

[Shannon C. Dealy]

On Mon, 19 Jul 2004, GlobalCirclenet wrote:

[snip]
> bales.  The strawbale fad is wildly impractical for a house because 80% of
> heat loss is through the ceiling, and that's not counting doors and windows
[snip]

The high relative heat loss through the ceiling is only true on more
poorly insulated houses, as the R-value increases uniformly throughout the
walls and ceiling, the heat loss per square foot of the ceiling
relative to the walls decreases until it becomes virtually uniform.  I
don't remember the numbers, but I think it was around R-40 or R-50.  The
reason for the difference is that poorer insulation levels (particularly
in the ceiling) generate stronger convection currents in the house, and
the stronger the convection current, the faster the heat is transferred.

There is a little more to it, but what it boils down to is that highly
insulated homes (regardless of insulation type) lose far less heat, and
lose it pretty much uniformly across the walls and ceilings, where poorly
insulated buildings lose alot more heat, and lose most of it through the
ceiling.


Shannon C. Dealy      |               DeaTech Research Inc.
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