Why should be choose green design? Sustainability must be the rudder that steers this ark called planet Earth, and nowhere is it more evident that design maps the course than in the new architecture.
The essential elements of sustainability in building feature passive solar heating (glass and translucent plastics), active solar heating (roof panels), rainwater collection (capture and containment), natural daylighting (skylights) and ventilation (open-to-air vents), energy-efficient electrical and mechanical systems (not just dimmers), resource-conserving materials, a tight building envelope (zone-appropriate insulation), low-VOC (Volatile Organic Compounds) finishes, and no-irrigation landscaping (goodbye lawns!).
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Footprint in the D.U.S.T., south-east of Tucson in Arizona’s San Rafael Valley, and hiding in the border zone, is a house that is so far off the grid, it almost isn’t there.
Specifically because of this location in the vulnerable Mexican borderland, architectural alliance DUST* has built Casa Caldera, a 48 sq. m. 2-bedroom house that is a solid, peaceful and almost completely sustainable retreat when the owner is there, and a well-hidden, almost impermeable fortress for the months when nobody is home.
At 5,000 feet of elevation, a house here must be a shelter in weather extremes that see winter temperatures around freezing and high summer days over 100 degrees F. But the owner was determined to achieve sustainability with a completely passive energy consumption: no air conditioning, no power lines, no furnace!
Lead architects Cade Hayes and Jesus Robles spent a long time making friends with the site, noting the movement of sun and wind and the efficient lives of the local lizards and Arizona Emery Oaks—which, Robles explains, “drop their leaves in the heat to conserve water in the trunk and roots, and grow green again in the cooler moist winter. It’s the opposite of trees in northern regions.”
To achieve such life efficiency in a house plan for the desert, Hayes says, they “rediscovered a local vernacular—a ‘zaguan’— a kind of open throughway that gives the house a channel for the breeze while at the same time merging the living space with a shady inner courtyard.”
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This sensitivity to the ecology of place means that Hayes and Robles must be like the cicada that have lived here forever, with their antennae on at all times, feeling the air currents, sensing the sun cycles, tasting the tensions that might suggest threat. “There can be narco-traffic and migrants coming through here,” Robles points out. Through the increments of weeks and seasons and the stringent demands of the client to stay off the grid and tread lightly on the land, the domestic and purely functional design of the house took shape.
“There are three rectangular zones, with living space and sleeping quarters flanking the central zaguan, and enormous, folding metal doors on either end of the zaguan to connect the living space with the landscape beyond,” says Hayes. The result of these two open frames is a sheltered vista that moves through the natural light of day and night, dawn and dusk, passively harnessing the breezes and scents of the weather. As a flexible and voluminous inner sanctum this part of the house invites lounging or dining, sleeping or dancing.
Scoria is a porous lava rock ubiquitous in this region of Arizona, known as the San Francisco Volcanic Field, but using it in the forced formwork concrete walls was not a straightforward process. With collaborative enthusiasm, Robles and Hayes enlisted Paul Schwam of Solar Lava to problem-solve, and the result was a machine that could grind and funnel the crushed cinder rock into a fine, workable reddish grit.
The colour of the walls blends with the surrounding earth, and their 18” thickness eliminates the usual Arizona love affair with AC by keeping the interior rooms cool. Robles is confident that these walls will last long past human concerns.
The only sources of heat are a small, elegant, cylindrical air-tight wood-burning stove and an open fireplace. All the cooling is achieved by the thermal offset of the 18 inch-thick scoria walls and the flow of air drawn through the building by natural air pressure oscillations on either end.
Ohio Sassafras unfinished planks were used in the living room and zaguan because, says Hayes, “it is rot and pest-resistant, and the effect is both rustic and warm.”
There is a single solar panel off-building and this supplies all the electricity needed for interior low-voltage LED lighting. In fact, says Hayes, “the house uses a mere 1.5kW from that one panel. The fridge and stove run on propane. The air-tight stove and fireplace provide all the heat and, in the coldest months, it takes about a day for heat to accumulate comfortably after the house has been closed up when the owner is away.” Windows are small to minimize direct solar heat gain during summer months, and hinge open at the bottom, where only a ghost might enter.
An existing well supplies all the water needed for both house and adjacent vineyard, where bad soil and dry conditions create the perfect terroir for rows of red grapes, and for a sustainable and sophisticated cowboy hideout.
*DUST is an alliance of architects and craftsmen, designers, builders and artists who follow the master builder tradition as a guild. The group, founded in Arizona in 2007 and led by Cade Hayes and Jesús Robles, has taken a love of the arid geography of the American Sonoran Desert and integrated its natural elements into their design philosophy in architecture, leatherwork, jewelry, furniture, and hardware.
Footprint in the D.U.S.T
by filmmakers and architectural photographers, AJ Brown and Joshua Ford.
South-east of Tucson in Arizona’s San Rafael Valley, and hiding in the border zone, is a house that is so far off the grid, it almost isn’t there. A moving film about the making of the award winning desert sustainable home by American architectures Cade Hayes and Jesús Robles founders of D.U.S.T. architecture.
Publisher’s Note: Judith Stapleton is a writer in the fields of science and medicine.