[Greenbuilding] skepticism about mass wall values

[Alan Abrams]

<The 'time to heat' a high mass house can be an order of magnitude longer
than a light house, and its return to ambient is similarly long.>

to what extent is that a factor, assuming more or less continuous occupancy
and forced air heating?  if it were a troublesome issue, it would be a
disincentive for moody climates.

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.

nder such extreme circumstances, peak load would still be a function of
"steady state" R-values, even though it might take hours or even a day to
reach that point.  the lag provided by the thermal mass might reduce annual
demand; then again, this "time to heat" might actually increase annual
demand.

-aa


Alan Abrams*
**certified professional building designer, AIBD
certified passive house consultant, PHIUS*
*certified passive house builder, PHIUS**
*Abrams Design Build LLC
*sustainable design for intentional living*
6411 Orchard Avenue Suite 102
Takoma Park, MD 20912
office  301-270-NET- ZERO (301-270-6380)
fax      301-270-1466
cell     202-437-8583
alan at abramsdesignbuild.com
www.abramsdesignbuild.com
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