re: solar closet results?
16 may 1997
greg burgin wrote:
>can you post this winter's solar closet results?
unfortunately, no. things have gone more slowly than anticipated, so "this
winter's" cabin solar closet isn't yet finished, and we've taken apart the
smaller structure we had on the roof of the science building at ursinus
college last winter. this fall, the 10x12' cabin had no insulation at all,
and lots of single pane glazing. it's insulated now, and part of an 18x24'
structure, 4 times larger...
the data logger and modem are now in the cabin, and the single-glazed poly
film/polycarbonate sunspace (8' tall x 8' deep x 24' long) seems to work well
on a day with some sun, becoming 120 f while the cabin stays at least 70 f,
when it's about 40 f outside, despite a southeast orientation and southwest
shading by trees. the sunspace air temperature peaks at about 11 am. some
shadecloth along the south wall of the cabin should lower the sunspace air
temp and increase its solar collection efficiency. the closet should help too.
at the moment, the sunspace is covered outside with 80% black shadecloth.
the cabin now has some overhead thermal mass (1400 pounds of water in 2l soda
bottles and 10' x 4" sewer pipes) but no heating controls as yet. it needs a
fan to blow down some warm overhead air at night, and a motorized damper to
close the sunspace<->cabin window at night or when the cabin is warm enough.
a lot of this work has been simply insulating the cabin including its glazing,
and making it more airtight. mundane straightforward predictable stuff, as
solar house heating should be. it was interesting to see the performance
improve as the cabin became better insulated, eg after adding 6' x 6' thermal
doors outside the single-glazed sliding glass door entrance on the north, and
a 4' x 5' thermal shutter outside the single-glazed west window.
i was surprised this spring, on removing some skylight thermal shutters, to
find 3" of foamboard had melted into an interesting-looking square parabolic
dish :-) i added a second layer of glazing to the 24 ft^2 of skylights and
painted the outside foam surface black, thinking that would reduce the heat
loss when the sun was shining. the skylights face west, with an elevation
of about 20 degrees.
>i've followed the solar closet discussions pretty closely and would like
>to see some numbers in addition to the day in november you've already posted.
me too. that day was in november of 1995. perhaps paul bashus can dig up an
interesting day from this winter. we have been sampling several temperatures,
the amount of sun, the windspeed and the electrical power consumed in the
cabin every 5 minutes for most of the winter.
>i'm very curious about how hot the closet got and how much heat it
>contributed during not-so-sunny weather.
me too. perhaps it will be finished and working well by christmas :-) the plan
is to present a paper at the next world renewable energy congress (sept, 1998)
based on this coming winter's performance. at the moment, finishing the closet
is a lower priority than making the cabin habitable and finishing the pond,
(volunteers welcome :-) altho it would be interesting to heat some water with
the closet this summer, or use it as a summer cool store.
>how well did it perform in the coldest part of the winter?
the sunspace and cabin did well, after insulating the cabin and fixing a
glazing condensation problem in january. the ground was too moist, and we had
too much water vapor coming out of the sunspace floor and condensing and
freezing on the inside of the sunspace glazing, which reflected the sun out
of the sunspace for most of the morning. the solution to this problem turned
out to be putting some astroturf on the sunspace floor, and digging some
drainage trenches around the cabin and filling them in with 3 tons of gravel,
in the rain, when it was 40 degrees outside. basic research :-)