# Inexpensive sunspaces

Discussion in 'Home Power and Microgeneration' started by [email protected], Nov 3, 2006.

1. ### Guest

http://www.teksupply.com/webapp/wcs...0&ftSearchDefaultPerPage=10&partNumber=105206

A 60' long x 12' deep lean-to sunspace might have

1 105206 \$269 60'x6'4" vinyl panel,
2 105192 \$159 12' clear gable ends, and
2 104419W \$339 12'x30' awnings.

That's \$1265, ie \$1.76/ft^2.

A 30' version might have

1 105197 \$189 30'x7' vinyl panel,
2 105192 \$159 12' clear gable ends, and
1 104419W \$339 12'x30' awning.

That's \$846, ie \$2.35/ft^2.

On an average 30 F January day near Phila, the small one might gain
2x8x12x0.9x415 = 71.7K Btu/day from the endwalls plus 7x30x0.9x1000
= 189K Btu from the south wall and lose 6h(70-36)402ft^2/R1 = 82K Btu
through the walls. With bubble wrap foil beneath, the roof might lose
6h(70-36)360ft^2/R3 = 24.5K Btu, for a net gain of 154K Btu, the heat
equivalent of about 1.5 gallons of oil burned at 80% efficiency.

A dark mesh curtain (eg 80% black greenhouse shadecloth) behind
the glazing could make it more efficient and and comfortable.
How can we airseal it?

Nick

2. ### GoedjnGuest

It is for people like that, that the short stake was invented.

3. ### Guest

http://www.teksupply.com/webapp/wcs...0&ftSearchDefaultPerPage=10&partNumber=105206

Alternatively, a 30' long x 12' deep sunspace might have

1 105197 \$189 30'x7' vinyl panel,
2 105192 \$159 12' clear gable ends,
8 4'x12' \$50 pieces of Dynaglas clear corrugated polycarbonate, and
1 308' \$154 2x4 frame

That's \$1061, ie \$2.95/ft^2.

On an average 30 F January day near Phila, it might gain 2x8x12x0.9x415
= 71.7K Btu/day from the endwalls plus 7x30x0.9x1000 = 189K Btu from
the south wall plus 12x30x0.9x620 = 200.9K Btu from the roof and lose
6h(70-36)762ft^2/R1 = 155.4K, for a net gain of 305.5K Btu/day, the heat
equivalent of about 3 gallons of oil burned at 80% efficiency.

The roof might have a silver tarp cover in summertime.

Nick

4. ### Nick HullGuest

It is for people like that, that the short stake was invented.[/QUOTE]

I thought rope was invented for them

5. ### Guest

http://www.teksupply.com/webapp/wcs...0&ftSearchDefaultPerPage=10&partNumber=105206
Two caveats:

1. If the glazing is flexible and the airpath to the house has 2 one-way
lightweight passive plastic film dampers, one near the top to let warm
sunspace air flow into the house and one near the bottom to let cool house
air flow into the sunspace during the day, this can act as an air pump on
a windy night: a wind gust pushes the glazing in, which makes cold air flow
into the house, and then it stops and the glazing expands and sucks warm
air out of the house. So maybe it's better to use motorized dampers with
2 thermostats in series, one that turns on when the sunspace is warm and
one that turns on when the house needs heat.

2. The sunspace needs a vapor barrier on the ground, eg plastic film under
a rug or some mulch (which is dustier), but even then, a single layer of
glazing can end up with a reflective layer of frost inside for most of
a cold sunny day. David Delaney's solution seems promising: put 1/4" black
dots on a 6" grid inside the glazing. I can imagine doing that with a 1'x2'
stencil and a paintbrush on a roll of flat polycarbonate. Or maybe wrap
a 2" x 1' paint roller with a plastic sleeve with 3 1/4" holes in it.

Nick