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re: plans for a passive solar, energy efficient two-story duplex?
26 jul 2003
larencorie wrote:
>> ...a typical passive solar house might be 30% solar-heated. psic says
>> an excellent one in the northeast might be 40% solar heated, following
>> all of their mass and glass guidelines religiously. these are fake
>> solar houses, since they are mostly heated by something else...
>i think "fraudulent" is a bit radical a term to assign to houses that
>may be using only 10% as much fossil fuel as typical houses built in
>the same area the same year.
would you call this a "solar house"? :-)
every day is sunny for george and charlotte britton of lafayette hill.
and for vivian vanstory of north philadelphia. vanstory's 1,280-square-
foot house uses 60 percent less energy than a comparably sized dwelling
built to minimum energy-code standards. the britton's 2,900-square-foot
house is blessed with energy bills 20 percent lower than one of comparable
size... the design of the house incorporates "passive" solar principles.
there are large double pane windows and sliding glass doors on the south
side. inside, tile floors and a trombe wall absorb the sun's heat during
the day and radiate it at night... a stone fireplace on the south wall
of the living area provides additional heat during colder months...
britton said... "we have a fire every day of the winter."
>so nick: how much did you pay to heat your house and water
>over the last year?
$0.00. then again, i live next door.
>> it seems to me that making a house more than 90% solar-heated
>> is very difficult, even on paper...
>in northern michigan the environment is so inconsistent,
>that it is very difficult.
traverse city looks tough. nrel says 490 btu/ft^2 of sun falls on a south
wall and 370 on a horizontal surface on an an average 25.4 f december day
with an average daily high of 31.2. e/w/n walls get 240/230/160.
>...in a cold, cloudy, inconsistent environment like michigan, where
>"the lake effect" dominates the winter weather, a very large sunspace
>is an excellent approach to the collector component...
richard nelson proposed building four houses around a two-story
sunspace/courtyard with a bubbleroof over hanging gardens and
tennis courts and swimming pools in cloudier parts of canada.
northern michigan might be a good place to put up a quonset-style
polycarbonate sunspace between two "normal" superinsulated houses.
it could provide warm air for the houses on an average day and
make hot water and store cloudy day heat with a well-insulated
tank full of warmer water.
a 32x32x8' tall house with r48 walls and ceiling and 96 ft^2 of r4 windows
with 50% solar transmission and 15 cfm of natural air leakage would have a
thermal conductance to outdoor air of 1024ft^2/r48 = 21 for the ceiling plus
24 for windows plus 20 for walls plus 15 for air infiltration, a total of
80 btu/h-f. it would need 24h(65-25.4)80 = 76k btu/day of heat in december
in traverse city, which might come from 22.3 kwh/day or 669 kwh/month of
indoor electrical usage, with no sun at all.
solar heating a house like that 100% in northern michigan looks easy, if
it remains a non-zero priority, after the jaccuzi, palladian windows,
corian countertops, and similar crap.
nick
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