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Inexpensive Retrofitting.... - Page 3

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Posted by JNJ on September 29, 2003, 2:47 pm


Ok -- now I'm with you guys.  That's a neat idea -- I'll have to look into
those once we finish up the insulation work next year (at the moment, I
already *KNOW* all the outside walls need insulation!).


Posted by Nick Pine on September 27, 2003, 12:50 pm

It may be very air-leaky. Dry indoor air in the winter is one indication.
Caulk a lot, and/or get a blower door test, or turn on a window exhaust fan
with the rest of the house windows and doors closed and walk around feeling
and watching (with a cigarette) for air leaks around windows, doorframes,
baseboards, air supply and return registers, and so on.

Once it's airtight, you might add a sunspace on the south side to collect
warm air on sunny winter days, a shoebox with several 8'x8' sliding glass
doors, or less inexpensive polycarbonate glazing, or maybe cloudy poly film
over double 12' 1x3s bent into $ bows with an 8' radius held together with
deck screws and 1x3 spacer blocks every 2'.

On 4' centers, 7 bows would make a 24'x8'x8' quarter-cylindrical space, with
top and middle and bottom purlins and a rebar ground stakes on 4' centers to
keep the bottom edge from moving. Wrap the bottom purlin with poly film to
keep it from rotting and lay a foot of plastic film on the ground with some
gravel on top to reduce air leakage. You might attach a single $50 layer of
4'-wide 20-year Replex clear polycarbonate with a spruce cap strip over each
bow, or attach a $0 16'x24' piece of 4-year greenhouse polyethylene film to
the end bows with 12' 1x3 cap strips.

Let warm air circulate from the sunspace to the house via 2 pairs of 2'x4'
high and low vents or windows in the house wall with one-way passive plastic
film dampers. Where I live, a sunspace like this would collect 0.9x8x24x1620
= 280K Btu on an average January day and lose about 6h(80-30)12.5'x24'/R0.8
= 113K, for a net gain of 167K Btu, about the same burning 2 gallons of oil.


Posted by JNJ on September 28, 2003, 1:24 am

Already working on these tasks as well as others.  I think more than
anything else I'm looking for some space heating solutions until we can
finish some of the larger scale projects that are slated for next year.




A sunspace has definitely been an option we're considering.  The house here
is uniquely situated -- first, it's an urban setting with houses on small
plots and all sitting on their property lines.  That means the sun space
would have to go in front or in back.  The former will not work (not enough
room) so we're thinking the back is our best option.  If you were to draw a
line from north to south, it would intersect the center line of the house
(side-to-side) with about a 60 degree angle facing west.

We have a small addition on the back that serves as a laundry room -- we'll
be remodeling it this year to make it more sturdy, and next year it will get
a new roof as well.  One thing I've thought of doing is creating a sunspace
behind it and tieing in through the laundry room or adding some skylights in
the laundry room to increase it's sun access.

Is there any value in adding skylights, domes or other similar breaks in a


Posted by nicksanspam on September 28, 2003, 10:45 am

Unless it's very shallow, eg transparent "solar siding" over a 6" air gap.

I'm not sure how an angle "faces west." Like this, viewed in a fixed font?

   S           .            W
     .   60    .
       | .     .       |
       |   .   .       |
       |     . .       |
       |       .       |
       |       . .     |
       |       .   .   |
       |       .     . |
               .         .
             front         N

Sure. About 4% of the floorspace for daylighting as high windows, and so on.

Sun Optics prismatic skylights transmit 40% more light than others, with no
hot spots. They ship the equivalent of 1 MW/week of fluorescents in Wal-Mart
roofs and other places...

For heating, on your small lot, you might go up, with vertical glazing, eg
south-facing clerestory windows above an EW ridgeline. Most of them might be
"dummy windows" with bare hydronic absorber plates behind them and insulation
behind the plates.


Posted by JNJ on September 29, 2003, 6:43 am
I suppose we could create a sort of solar furnace with piping into the
house, but I like the idea of building a room -- more value to the home,
more interesting, and so forth.

The open end of the angle is due west.  Something like the below....

X   --------
X   |          |                    N
F   |          |                 ./
R   |          |             ./
O   |          |         ./
N   |          |     ./
T   |          | ./
X   |          |
X   --------

If I were to stand in the exact center of my house, facing the back yard,
north would be off to my left.  Draw a left-to-right bisector of the house
and north is around 120 degrees from the right side of the line.  (As you
might have guessed, I've never tried to describe this in words so I'm kind
of groping at words here).



Interesting idea -- I hadn't considered faux windows.  I was figuring on
just putting some additional window structures in when we redid the roof
next year.


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