re: ultra low-rent experiment
29 jul 1999
steve sowders wrote:
>try living in a tent...
not very burglar proof or solar heated. how about this: put some black
plastic film on the ground (about 2 cents/ft^2), pile some old rugs on
top of that, then stack up 90 55 gallon water drums 3 high (with a few
deadmen between them) in a 9' high x 16x16' square. (a couple of years ago,
i collected about 300 free drums from a local turkey packing plant.)
put a $50 double 1x3-bowed plastic film greenhouse above that, fill the
chicken wire/poly film greenhouse floor with plastic bags full of dry
leaves, and surround the drums with more bags of leaves, with a layer of
greenhouse plastic film over them to slow solar degradation. hire an
architect to decorate the walls as needed (or use transparent leaf bags,
eg clear 55 gallon drum liners, for that leafy look.)
put some more bows from the roof to the ground (bolted to old tires filled
with dirt) on the south side, and tie the bags of leaves closer in to the
drum wall on that side to make a heat-collecting sunspace, with openings
near the south drumwall bottom and a couple of 2x3' one-way dampers made
from dry cleaner bags hung over chicken wire frames near the top of the
wall to allow sunspace-warmed air to flow into the house during the day
and prevent reverse airflow at night and on cloudy days.
r30 insulation and 1280 ft^2 of walls and ceiling make the conductance
about 50 btu/h-f. a square foot of r1 south sunspace film gains about 900
btu/day in philadelphia in december and loses about 6h(80f-30f)1ft^2/r1
= 300 btu, for a net gain of 600 btu, so the 256 ft^2 sunspace can supply
about 154k btu/day of heat for the house. meanwhile, the house needs about
24h(70f-30f)50btu/h-f = 48k btu/day (3x less than the sunspace can provide)
to stay warm in december in philadelphia. piece of cake.
with 40,500 pounds of water, c = 40.5k btu/f, and rc = 40.5kbtu/f/50btu/h-f
= 810 hours (4.8 weeks :-) so keeping the house at 75 f on an average day
means it cools to 65 f when 65 = 30+(75-30)exp(-t/810), ie t = -810ln(35/45)
= 204 hours or 8.5 cloudy 30 f days in a row.
fold the greenhouse film up along one lower edge to make a roof washer,
collect rainwater in a few of the upper drums, add a sawdust toilet
(a la humanure handbook) and bob's your uncle.