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Solar Flare wrote:

Since November here we had about 2 hours total sun in 45 days...

Where is here? How much is about? How long is November?

Now if my house is 1800 square feet...

And it needs 50K Btu/h, with 3200 ft^2 of R32 walls and ceiling, and
it's T (F) outdoors, with 50K = (70-T)3200ft^2/R32, T = minus 430 F.
That's a very cold day :-)

Nick, where does 3200 ft^2 come from?
A square house 42' on a side has 1764 ft^2 = ~1800ft^2 floorspace.
With 8' tall walls, there are 4*42*8=1344ft^2 walls.
A 42*42 floor plus 42*42 ceiling is 3528 ft^2
for a total of 4872 ft^2 surface area.

I didn't count the floor area.

...If the 1800 ft^2 house is insulated to Nick's proposed R=32...

M. Flare might use 8" SIPs, and put most of the windows on a sunspace.

(with no allowance for air exchange),

Another 15 Btu/h-F for 15 cfm, or less, with a heat exchanger.

Regarding Nick's DDD,
How much insulation is between the interior floor, and the heat store,
the same R=32?

The 8' Phila D-cube had R15.5 walls and ceiling. R22.7 worked for
Saskatoon.
In Phila, we might let floor leakage supply half the heat on a 30 F day,
ie
about (70-30)10 = 400 Btu/h. If the 6'x6' store is 150 F on an average
day,
it can supply 400 Btu/h through a (150-70)6'x6'/400 = R7.2 floor.


Not until you tell us how you're replenishing the heat in the under-floor
storage. It's easy for someone to just say that heat leakage up from the
under-floor storage will *help* heat the building. But a *true* engineer
would have some detailed figures on that heat storage. Like how it gets
heated, how much it looses to the ground, how long it takes to warm it up on
sunny days.

Until you do a *real* study of the under-floor storage and its energy
'cycle', claiming any benefit from it is just 'smoke and mirrors' trying to
"baffle 'em with bull****".

daestrom