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Posted by Kris Krieger on January 3, 2008, 2:22 pm
>
>>
>>> Any architects on this ng from southern Louisiana? Would like to
>>> discuss insulation in walls vs. attic. I suggest a 30R for attic
>>> and only 11R for walls (4"). There is a myth out there that walls
>>> need to be 6" to give southern walls adequate insulation. Crock of
>>> grits! I bump into someone who keeps this myth going every now and
>>> then (like now - client - who happens to be an engineer who thinks
>>> he knows more than God).
>>
>> Why is more insualtion bad?
>>
>> I lived in a place here (Houston area) with low insualtion, and this
>> place (decent insulation). I could feel the heat (and January chill)
>> through the
>> walls in the other place, feel lots less here. Main loss ia the
>> windows - double-paned, but the sumbass aluminum frames radiate like
>> mad - had great ones in Canada, wish I could recall what type/brand
>> they were (that was 1993, so I've forgotten).
>>
>> Air-conditioning is a lot more expensive than heat, so it always
>> mystifies me that people think you need less insulation in a hot (esp
>> a hot and extremely humid) climate.
>>
>> YOu might call it a myth, but personally, I'd take more/better
>> insulation over less insulation ANY day.
>>
>> I also got tech-shield and tyvek. I guess that, in your book, that
>> makes me an even bigger idiot. I'm not an engineer and I certainly
>> don't think I know more than God, OTOH, I *do* know what my energy
>> bills say, or more to the point, *don't* say.
>
> Insulation in the envelope is supposed to keep the outside temps from
> coming into the inside.
> Cold always flows to hot, not the otherway around.
But it's not as though heat transfer only occurs when the cool air is
outside the building.
> So in the summer, when the AC is on the cold is trying to get to the
> outside, cold to hot.
> Insulation doesn't work to the optimum in this condition amd more
> insulation wouldn't help either.
> Having a tightly sealed envelope does.
But isn't that like saying that a hot roast put into a box will cool down
if placed in the snow, but a pint of ice cream in the same box would not
melt in placed out in the hot weather...? Entropy always occurs -
molecules in an excited state (heat) will preferentially seek a non-
excited state (cold).
All I know is that, even aside from entropy, I've spent some summers in
non- or poorly-insualted places, and the walls felt hot, meaning, the AC
had to work harder to overcome the huge numbers of excited molecules
which are available to exchange their energy state with the preferred
non-energetic/cool state. OTOH, a well-insualted place will not have
warm or hot walls, or at least, they won't be *as* hot/warm.
WIndows are another matter - as I'd mentioned, we'd gotten replacement
windows in the first house in Ontario, and in Winter, the windows were
warmer to the touch than were teh walls, IOW the windows (and their
frames) were better-insulated. In this place, teh windows are double-
paned but they suck - a lot of heat-exchange occurs because the frames
are single-layer aluminum. IOW, crap. Also very difficult and expensive
to replace, because they are basically mortered into the brick.
I of course can't speak as to r-11 versus r-13, but given the cost of air
conditioning, which ain't about to go down, given that most electricity
is still generated by burning either coal or gas, is a little extra
insulation THAT much of a "wasted expense"...? What are the long-term
figures? I mean, some people thought we were nuts for "wasting" money on
the tech shield, but the figures indicated that, in this climate, it'ds
pay for itself in jsut a couple years.
I just don't think that extra insualtion is as pathetically stupid as the
OP intimated by the tone of the post.
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