[Cob] PaperCob!

[Clint Popetz]

On 7/6/06, GlobalCirclenet <webmaster at globalcircle.net> wrote:
>
> Radiant heat radiates in all directions at once, but convection heat does not. Can anyone not know that it's warmer near the ceiling than near the floor? Warmer air transfers heat through the ceiling/roof faster than cooler air through the walls.

Yes, it's warmer near the ceiling.  And since the temperature gradient
between the inside of the ceiling and the attic (or the roof, in a
cathedral ceiling) will be therefore greater than the gradient between
the inside/outside of walls, and since heat transfer goes as the 4th
power of the temperature difference, heat loss will be greater through
a roof.

So yes, you should concentrate on insulation "up there."  But after
that, walls are a huge heat loss.  This is compounded by the fact that
the walls typically have more punctures (for openings) and often don't
even have a vapor barrier, and their insulation has often settled,
leaving a big gap at the top.

I wasn't contesting that insulation in the attic is a good thing.  I
just wanted to clarify that insulation (and a good vapor barrier) in
the walls is very important, in contrast to your statement:  "Heat
rises, and no amount of R-value in the walls alone will reduce total
house heat loss enough to notice."  If you had no insulation on top,
perhaps that would be true.  But not in the more common case of having
an insulated attic.

-Clint

> paul tradingpost at lobo.net
>
> Beware of all enterprises that require new clothes.
> --Henry David Thoreau
> *********** REPLY SEPARATOR  ***********
>
> On 7/6/2006 at 2:07 PM Clint Popetz wrote:
>
> >On 7/6/06, GlobalCirclenet <webmaster at globalcircle.net> wrote:
> >>
> >> >Unless I've missed something here, I think this still-conceptual wall
> >> >system may be the easiest way to build an almost-all eco-earthen house
> >for
> >> >extreme climates, that's round, warm, and fuzzy, and still doesn't
> >require
> >> >any high-tech industrial equipment before, during, or after.  The Peak
> >Oil
> >> >Papercob Wall... can you find fault with it?
> >>
> >> I'm afraid it's a nobrainer. Most heat loss is through the ceiling,
> >> windows, and doors, obviously. Heat rises, and no amount of R-value in
> >> the walls alone will reduce total house heat loss enough to notice.
> >
> >Aiee!  No!  It is true that hot _air_ rises, but heat travels in all
> >directions at once.  Heat loss through walls is a huge deal.  I'll
> >admit your attic is the first place to look if it's not properly
> >insulated, but after that, getting a good vapor barrier on a wall, and
> >decent insulation, and looking out for thermal bridging...these things
> >are a must for a well-insulated house.
> >
> >-Clint
>
>
>
>
>
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