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re: cement filled pipe?
14 nov 2001
ron purvis wrote:
>hey nick, does a green house really have anything to do with
>alt.energy.renewable...
sure. you can easily make an inexpensive 100% solar-heated house with
lots of daylight by putting a plastic film vapor barrier on the ground
under a used carpet and adding some thermal mass inside and filling the
space between 2 plastic films with air during the day and tiny cold soap
bubbles at night in wintertime and surrounding the greenhouse with a
chain link fence for burglars. shade the house with foam in summertime.
commercial greenhouses inflate film walls with a 50 watt blower on cold
days. to add foam , fill a film trough near the ground with a 10% sodium
lauryl sulfate solution and a 100' 2" pvc pipe just under the surface
along each edge of the greenhouse. at night, turn on a shop vac until
the bubbles (about 1000x the solution volume) reach an air return hole
at the peak covered with insect screen. when the foam hits the screen,
it moves a microswitch arm that turns off the shop vac until the foam
begins to recede. the vac runs for a few seconds per hour all night.
with r20 6" foam (1/16" bubbles at 50 f mean temp) a 70 f 14'x96'
greenhouse needs about 2350ft^2/r20 = 118 btu/h-f, ie 4700 btu/h or
113k btu on a 30 f day, or 564k btu for 5 cloudy days in a row.
this might come from 564k/(120-80) = 14.1k pounds or 1760 gallons or
220 ft^3 of water cooling from 120 to 80 f, eg 32 dark-colored 55 gallon
water drums along the south side, with an inner poly film skirt.
i bought 2 14'x96' greenhouse kits for $568 each, plus $25 delivery
from schwarz & sons in wilmington. the standard labor to put one up
from scratch is 3 people, 1 day (if they know what they are doing :-)
nick
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