re: more details
27 oct 2004
stuart gold wrote:
>...i hired an insulation company to blow insulation (granular cellulose
>treated with fire retardant) into all the remaining walls and ceilings.
>i think that it is also about r19 for the walls and the ceilings was
>a double thickness that they said would be approximately r35.
a 16x24x8' tall studio like that (what are your dimensions?) might have
a thermal conductance of 16'x24'/r35 = 11 btu/h-f for the ceiling + 36/2
= 18 for 3 12 ft^2 double-pane windows + 604 ft^2/r19 = 32 for the walls
+ 0.5x16x24x8/60 = 26 for 26 cfm of air leakage, if it is well-caulked.
the total is 87 btu/h-f. used 8 hours per day, it would need about
8h(65-51.1)87 = 9674 btu per day of heat.
a 4'x8' collector with r1 glazing with 90% solar transmission might gain
12.9k btu of net heat on an average day, if collecting 130 f air.
>the basic solar collector design that i have come to in my research is the
you might simplify that, and build two.
>1. 1" x 6" wood frame with a plywood back. approximate dimensions 4' x 8'.
you might omit the plywood and staple a 4" saran wrap skirt around
the wood frame before attaching it to the wall with brackets or 4x4
blocks, then spray expanding foam between the frame and the wall,
letting the saran wrap conform to and protect the shingles...
>2. 1 1/2" rigid insulation covering the bottom and sides to a height of 3".
>channels created to funnel heated air.
you might omit all that.
>3. 4' x 8' tin plate (flashing) painted flat black as an absorber. holes
>(1/16 ") drilled through the surface to allow flow through.
and use a single layer of black window screen instead.
>4. surface is dual walled polycarbonate sealed with silicon.
flat ge lexan polycarbonate from a 4' wide roll, over a vertical rib on
the wall to keep it in tension, ie to avoid oilcanning or dishing-in.
>5. insulated 6" ducts using a energy efficient fan in the output duct to
>blow heated air into the studio.
and use 4" x 4' slots at the top and bottom, with a a one-way plastic
film damper and a board over the top slot, both hinged 1' above it
and lower the board in summertime.
you need 5x9674 = 48.4k btu for 5 cloudy days in a row, eg 48.4k/(130-80)
= 967 pounds or 16 ft^3 of water cooling from 130 to 80 f, eg a 24'x4'x2"
layer of water in a 4'x24' poly film duct on top of a 4'x24' piece of
aluminized mylar film on top of a 4'x24' piece of welded-wire fence under
the ceiling, with a slow ceiling fan in series with an occupancy sensor
and a room temp thermostat to bring down heat as needed.
an eyebrow above the collectors and windows could shade summer sun and
augment winter sun. at 34.9 n lat, the max sun elevation on 6/21 is
90-34.9+23.5 = 79 degrees. tan(90-79) = d/(8+d) makes d = 1.93'. you
might add a 2' projection 2' above the collector/window top edges with a
reflective surface below that slopes at 45 degrees down to the top edges
at the wall.