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re: polypropylene shade cloth in residential air system
12 may 2001
david delaney wrote:
>> ...a bubblewall sunspace full of thermal mass, eg dark 55 gallon drums
>> or a waterwall like anna edey's?
>i considered many thing to get to this point, but not a waterfall!!
waterwall vs fall... i was suggesting two layers of sunspace glazing,
and filling the space between them with soap bubble foam at night and
on cloudy days (tiny cold bubbles are almost as good as fiberglass
insulation.) the sunspace could have lots of thermal mass on the north
wall, eg 55 gallon drums stacked vertically 3-high, or a "waterwall,"
with 55 gallon drum liners sitting on 1' wide plywood shelves supported
by 2x4 posts, with welded-wire fencing on the sides. the sunspace could
become 24-hour living space, with direct gain during the day and night
insulation. then again, the sunspace might contain a licl waterfall :-)
>> >...a duct draws hot air from the attic for occasional direct room heating.
>> >another duct conveys hot air from the attic to a sub-slab bin of stones
>> >for additional storage and main heating of the house by the warm slab..
>>
>> i wonder how much electrical energy this will consume in a year.
>
>saunders used 1/4 hp variable speed fans that drew 300 watts at full
>power. the fans ran much slower than full power most of time, but ran
>most of the time.
sounds like 2 or 3 of those fans might use $500 per year, comparable to
the fuel bill for a superinsulated house, without all the mass and glass.
bill shurcliff decided superinsulated houses were better than "solar
houses," after that book.
>i will make the main down duct and fan diameter as large as
>is practical, to conserve power.
sounds good. norman used 2'x2' vertical ducts with 16 possible fan power
levels from his homebrew z80 controllers. he used to say that a fan's
efficiency was about the same as the blade diameter in inches. "the fan
laws" say cfm is proportional to rpm, and static pressure is proportional
to rpm^2 or velocity^2, and fan power is proportional to rpm^3. you might
use 4'x4' ducts with 4' diameter 21k 315 rpm 86 watt grainger ceiling fans
with solid-state speed controls.
>can you suggest a forum where i could get an authoritative opinion on
>any health concerns from outgassing from the hot polypropylene?
nfpa? somebody (mit? alex wilson?) has a catalog of "green building
materials..."
>i am hoping to get air temps well above [110 f], but only in the up-draft
>near the absorber, as shurcliff says saunders intended. unfortunately,
>at the time "super solar houses" was published in 1983, the cliff house
>had just been finished so the book has no experience info. i tried tracking
>down antonio pulsone, the builder and initial owner, but no luck so far.
it's probably still there. norman showed me the outside about 4 years ago
and said it had about 10k pounds of water in the attic and 20k pounds of
rocks in the basement, and the heating system used about $100/year of
electrical energy. the (new?) owners had built a large fireplace in the
sunspace, but norman said they didn't use it often. maybe you should go
camp in their driveway :-)
>> >any alternatives to polypropylene for the material of the semitransparent
>> >absorber? saunders used metal vanes coated with a chrome green pigment.
>>
>> he also used black window screen behind non-window south glazing...
>
>i'm very fond of the ability to draw the absorber aside at a moment's
>notice for brief or extended periods.
you might put it very near the north wall, so you could enjoy the sun
in the sunspace while the warmer air stays far from the cold glazing...
nick
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