RFS Solar Work 2008-2010
Art Studio and Greenhouse
In this scheme the design of the greenhouse and ceramics studio was determined. The greenhouse provides additional warm air for the main house and acts as a passage to the dining roof deck. On the south wall of the studio the 3 window/door bays are part direct gain, part active collector, the hot air being drawn down to a thermal storage bed under the slab. A portion of this sub-slab bed is devoted to air from the kiln room where waste heat is retrieved and stored for later space heating. A construction detail of this bed is shown, as is the diagrammatic structure of the studio and a preliminary sketch of the sub-slab bed plan. The second story bridge to an additional studio was eliminated from the design.
The studio walls and roof are 4.5" and 6.5"(R29 and R42); further the walls are enhanced by R3 from the application of 3" air-entrained autoclaved concrete, adhered to the outside of the oriented-strand board in 2'x8' panels by adhesive and screws. This fire protection is also an excellent substrate for the required (by covenant) stucco. The Sips create a tight seal in the walls by a tongue and groove edge in the foam with 2 grooves for additional applied foam, then zipped together with embedded steel cam-locks. Columns on the south facade, and curved walls are built with 8' AAC block, which is mortared with thin set adhesive. The South facade is an air collector, where the blocks are glued together with apertures for the transport of air.
The air collector draws in air from the top of the space where it descends through a channel with exterior insulating glass and interior single pane glass. A metal screen is held taut in the center which helps transfer the sunlight to heat and transfer with some friction into the air stream. The air then has a labyrinth to traverse on each side back to the fan which releases the air into the room, having deposited some of the heat into the slab, where it conditions the space at night as the interior air temperature drops. This process destratifies the air temperature in the space both vertically and horizontally. Readings of the temperatures in the hottest level of the collector have read as high as 162 degrees F, which indicates that the fan is slightly undersized for the amount of friction. None the less no additional heating system acts as a backup, and the chimney built in case a wood stove would be desirable has never been used, with the space used now for many winters. In summer east to west cross ventilation at night with windows and insulating blinds closed at night keeps the temperature no higher than 72 degrees F. Natural light from the south facing roof monitor eliminates the need for artificial lighting during the day, with mirrors reflecting the low angled winter sun into the space, but allowing only sky-dome radiation light in during the summer when the sun angle is high.
The greenhouse is a passageway from the house to the studio and to the roof terrace over the studio. It is, also, now the primary heating source for the house. 2 small PV panels under the glass drive a fan which transfers the warm air into the house; while not a perfect match the amount of heat trapped determines the of CFM delivered without the need for an electronic controller, and the need for extending a power source through the concrete wall. The double-pitch and the curved south wall, made this a difficult custom structure to build. The inner trusses are oriented on lines that intersect a hypothetical extension of the inside dome center point. The parts were cut from aluminum plate and L angle on site and fasten together with rivets and stainless screws. The pre-existing south facing wall of the house was painted a dark purple to better absorb the solar gain. The fan running under full sun can produce 1,000CFM of air delivery.