Nick Pine's State of the Art Home
Heating Sunspace
This is a description of Nick Pine's new cutting edge sunspace design
and build.
The sunspace is three stories tall and is designed to provide
substantial space heating for the home it is attached to.
This is a new design with innovations in glazing, air distribution,
and heat loss control -- some great new ideas to learn about and use.
There is a comments/questions at the end if you want to participate
in taking this design further, or have questions about applying some of
its elements to your sunspace.
Thanks very much to Nick for providing the story on this exceptional
sunspace!
The Story From Nick
This sunspace is 12' deep and 32' long and 28' tall.
The end walls are twinwall polycarbonate, and the roof is 2 single layers of
corrugated roofing polycarbonate.
The south wall has 4'x8' double-glazed panels with 2 layers of 10 mil HP92W
clear flat polycarbonate with eight 2'x4' operable vent panels at the top. Each
glazing panel is gently inflated with welding argon via a tire valve.
Tthe materials for each 4'x8' site-built glazing panel cost about $100, and
the double glazing has 85% solar transmission, vs $560 and 63% for a 4'x8'
insulated glass Home Depot fixed window with a lot more wood and a lot less
glass. The two 10 mil polycarbonate layers are squeezed by a ripped 2x4 frame in
these panels. I wanted to just bolt the 2x4s into an integral modular structure
with no extra studs, but my builder friend Marcus Sadler insisted on 24' 2x6
studs on 4' centers.
The deck in is 8'x32', 16' above the ground. The corrugations in the top
layer of polycarbonate run north and south and match the metal roof
corrugations. The corrugations in the layer beneath it run east and west.
Warm sunspace air enters an attic duct through holes above the central pair
of 4'x8' doors.
Mesh Inside Glazing Improves Performance
Click on images for full size
A mesh curtain with 2 layers of 50% black greenhouse shadecloth keeps cool
house air near the glazing and blocks some radiation from the dark insulated
house wall to the glazing and makes the sunspace more private and comfortable.
The house air is only heated as it passes from south to north through the
mesh.
Fran and Stephanie (right picture above), who used to drive a Caterpillar
D9
bulldozer.
Stapling the shadecloth layers together
After adding a layer of Scotts weed barrier, which didn't
last long in the sun and heat (over 130 F in December.)
Air Distribution System
These trenches carry cool house air from the basement to
two floor outlets between the shadecloth and the glazing.
Builder Marcus overdid them and put the wood thermal mass on the wrong side of
(the inside of) the insulation.
In retrospect, deheading 4 55 gallon steel drums and laying them end-to-end
inside each trench inside plastic film would have been easier.
Performance -- What worked, What Didn't, Suggestions for Future Designs
My 1820 stone farmhouse has stone
walls with 2" of sprayed foam on the outside and 6" of fiberglass outside
that, but it's air-leaky, with about 10 gpm of groundwater sucking heat out
of the lower part of the walls, so this sunspace has a hard time keeping the
house warm when it's less than 20 F outdoors.
We used butyl rubber tape to seal the flat polycarb layers, and it
has partially melted in high temperatures. Silicone caulk or strips of EPDM
rubber might have worked better.
