Inexpensive sunspaces

[nicksanspam]

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

[Joe Fischer]

I wonder if my little town would allow a lean-to like that, there is a group of people trying to get control of city council and force people to keep up and upgrade their property, with a $500 fine if a citation is issued.

I could put two of the big ones on my SW wall, one above the other.

What roof? Does a lean-to have a roof?

Rather than bubble wrap, could I get the same effect if I raised the CO2 level in the lean-to up to about 50 percent?

I have a sample of black chrome plated copper from the 1970s, if that were still available, it might increase the air temperature quite a bit.

Try to think of a way that I could make it look enough so that nobody would object, I might even want to make it so that I could work in the sunspace on cold days.

I could do a lot more work on my cars and even do some cut vinyl applications on vehicles if I had a sunspace, but there are a lot of catch 22s, I would be allowed to do more if I could get the property zoned commercial, but that might cause me to lose my old age homestead exemption on the real estate tax. It would be nice to put a sunspace on the SE wall, so I would have some heat earlier in the day, but it faces the street.

If there is some design that looks good, it would be worth extra money to DIY install wood or plastic ducts on the house with .065 in thick glazing, with white louvers on the outside to block the heat on warm days, and maybe the white louvers could be made to look like weather board or vinyl siding when closed, and look more like a conventional house.

I would also be interested in ducting, a fan and filters to be able to pull warm air from the attic on cool days, it burns me up to think that my car stays warmer than the house from the sun, even with the heat on in the house.

Joe Fischer

[Goedjn]

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

[nicksanspam]

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

[Nick Hull]

I thought rope was invented for them ;)

[nicksanspam]

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.

1. 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