[Greenbuilding] skepticism about mass wall values

[RT]

On Wed, 24 Apr 2013 07:05:07 -0400, Alan Abrams  
<alan at abramsdesignbuild.com> wrote:

> but the subtext of all this is whether an AAC wall is sufficient on its
> own, as its proponent put forth.  my position was simply that in a
> 4000-5000 HDD climate, with long periods of low temps and no sunshine,
> additional exterior insulation is advised.

I don't know nuttin' about nuttin' about AAC, primarily because the  
product isn't readily available in my neighbourhood so I have no interest  
in it.

But that doesn't stop me from having an opinion.

What I do know is that an mass material and ideal insulation material  
would be at opposite ends of the thermal spectrum.

I also know that the usefulness of a material as beneficial thermal mass  
is directly proportional to its density.

I also know that the usefulness of the aerated concrete product as an  
insulator is due to its reduced density due to air entrainment in the  
concrete matrix.

So it seems that it'd be neither a very good thermal insulator nor a very  
good thermal mass material ... a half-(m)assed attempt to be both but  
doing neither very well and costing a premium (over the cost of regular  
masonry) for the privilege of being thermally trans-gendered.

I can't help but wonder if it might not be better (ie lower cost, lower  
embodied-energy, better thermal performance) to simply use a  
run-off-the-mill, regular density masonry exposed to the interior and  
outsulate it with a good insulation material ?
-- 
=== * ===
Rob Tom					AOD257
Kanata, Ontario, Canada

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