Our Simple Home
Nick Pine
>Nick Pine wrote:
>> Although greenhouses cost less than $1/ft^2, and they can be
>> solar heated with thermal mass and bubblewalls ("replacement
>> foam insulation.")
>...I'm not sure many folks would be comfortable living inside one.
They use them for cows now. I can think of two issues for people: they
tend to collapse in heavy snows, unless they are well-heated and have
poles in the center, and they aren't burglarproof. We might add two chain
link perimeter fences with electrified razor wire on top and motion
detectors with powerful lights and sirens and dogs between the fences,
recalling the ambiance of the Centre Nucleaire inside the Polygone
Scientifique in Grenoble...
A single 100x150' chain link fence might add $5K to the cost of 2 $2K
30x100' greenhouses, raising the total to $1.50/ft^2. H. Schwartz & Sons
of Wilmington, DE (in whom I have no financial interest) sell their
26'x96' "Leeward" gothic-arched greenhouses for $1996. (302) 656-0276.
Three people can put one up in a field from scratch (including the
ground sleeve foundation) in a single day.
>...they might, if you make some additions and changes. Say, change it
>from 2 year poly film to plexy and steel so that it'll last,
Greenhouse poly at 5 cents/ft^2 has a 4 year guarantee. The labor cost to
replace it on a calm day is 1-2 cents/ft^2. It might last 15 years with
shadecloth in summertime. Thicker mesh reinforced poly is stronger and
lasts longer and costs about 20 cents/ft^2. Plexy is more difficult to
insulate with replacement foam, and steel is opaque, solar-gain wise.
>add insulation and a good solid floor.
Maybe loose fill between the endwall or north wall poly films. The south
wall cavity needs to be filled with air during the day and soap bubble
foam at night in wintertime and vice-versa in summertime. Mike Oehlert
suggests a good solid layer of old carpeting over some black plastic
film on the ground in his "$50 and up Underground House Book." We might
use light-colored carpeting with some waterwall room dividers down the
center to store solar heat, a la Anna Edey, thick sections of double-stud
walls with plywood shelves and sides made from welded wire fencing as
compartments for water-filled dark plastic film 55-gallon drum liners.
They might have bookshelves on the north sides.
With R20 foam, the greenhouse has 3000ft^2/R20 = 150 Btu/h-F of ceiling
thermal conductance plus 2000ft^2/R20 = 100 for the walls, a total of
250 Btu/h-F with the foam in place. It needs about 5x24(70-30)250 = 1.2
million Btu over 5 cloudy days in a row. This might come from 24K pounds
of water cooling from 130-80 F, eg 48' of 1' thick x 8' high waterwalls,
eg 3 16' room dividers. The Leeward ridge peak is about 14' above the
ground, so the room dividers won't shade the north half much.
>For those that demand the utmost in civilization things like interior
>walls, electricity, running water, bathroom and kitchen fixtures, and
>the like are also required. Can you still do this for under $1/ft^2?
No.
>I can certainly think of ways to try though. Thin sheet steel over
>a steel frame, with recycled windows, doors, fixtures and hardware.
The walls might be mostly steel, raising the price 10X, if you insist.
We really only need a bubblewall strip along the south side from say,
8' above the ground to the ridge peak. The Leeward frame is 1.315" OD
schedule 40 hot-dipped galvanized steel water pipe bows on 4' centers.
>Insulated with papier-mache or papercrete made from old newspapers,
>boxes or any other clean waste paper. Floored with a poured-in-place
>adobe mix from the site.
That could store solar heat...
>Interior walls could be canvas dipped in portland cement, or even
>a tilt-up sandwich made from canvas/cement on the outside with
>papercrete or papier-mache mix on the inside to provide 4 to 6
>inch walls and reinforced with steel or wood studs where doors
>and cabinets need to be hung.
Sounds funky...
Nick