When a friend suggested that Hadley and Peter Arnold consider a house for sale in the posh Los Angeles enclave of Bel Air, Hadley burst out, “That’s ridiculous—we can’t even afford a mailbox there!” To which their friend replied: “That’s okay; this house happens to be about the size of a mailbox.”

As the Arnolds soon discovered, the property was not in the Bel Air of grand gateways, lavish estates, and manicured lawns, but in the adjoining, more down-to-earth neighborhood of Beverly Glen, a place with small, pleasingly bohemian cottages nestled on slightly scruffy lots, thick with wild grasses. Steep canyon walls and an active road, hemming in meager swaths of buildable land, had helped define the local character.

Hadley and Peter—architects who met as grad students at SCI-Arc—were drawn to the 650-square-foot house their friend had recommended: a white, nearly cubic, wood-and-glass structure from 1941 by architect Cliff May. They bought it—and not only set up their small architectural office there, but also made it their home. A baby daughter would soon join them.

About a year later, their next-door neighbor leaned over the fence and proposed selling the Arnolds her own property, the brambly, overgrown site of another small house. A favorable deal, plus the rare opportunity to create a separate home and architectural studio just steps apart, was too good to pass up. They leaped at it.

Living small indoors, but living large in the landscape, appealed to Hadley and Peter, who have taught sustainable-architecture studios—first at UCLA and, since 2002, at Woodbury University in Burbank, where they formed the Arid Lands Institute to research innovative responses to climate change and water scarcity. Their locally famous Dry Studio involves wild and bumpy road trips across the arid west, where the entire class camps out, designing and erecting temporary drought-responsive structures. For the Arnolds, moderation is “the wave of the future... essential for a sustainable nation.” Naturally, once they’d purchased the neighbor’s property, unsolicited offers flowed in from developers eager to erect a cluster of multistory residential units on the one-third-acre lot (only a third of which is buildable). Yet Hadley and Peter—determined to preserve the canyon’s surviving landscape—resisted market pressures. Instead, they envisioned renovating their newly acquired one-story, 835-square-foot home and happily moving in. But the building, they soon discovered, was too rotted out to salvage.

Taking the house down to its foundations, however, was “much, much more than we’d bargained for,” recall the architects, who nevertheless saw this radical step as the only viable option. For the project to qualify as a renovation, rather than new construction (a far more costly endeavor, given code requirements), it could not extend one centimeter beyond the existing footprint.

Their new home, Canyon House, now stands on the foundations of the cottage built for the Lohrie family in 1947 by Rodney Walker, who went on to design three Case Study Houses. The Arnolds’ scheme, based on the original structural bays, is very much in the spirit of the Case Study program. Like those homes, and such forerunners as Cliff May’s white cube next door (now the Arnolds’ architecture studio), Canyon House emphasizes spatial flow, openness, and transparency, with sweeping glass walls and generous openings that bring in ample sunlight. The design encourages seamless indoor-outdoor living—a goal arguably achieved more fully in Canyon House than in the more opaque and introverted, plywood-clad Lohrie House. With exposed Douglas-fir framing and hand-troweled concrete floors, the new construction also shares the Case Study Houses’ economy of means and exposed structural materials as final finishes.

Walker was among the early California modernists who translated the ideas and spatial character of international modernism into a West Coast idiom, engaging the landscape with warm, earthy materials such as wood instead of the original style’s hard-edged, industrial palette. Canyon House’s cedar cladding and Douglas-fir posts and beams similarly relate to the setting’s colors and textures: native yucca, sage, poppies, and tall grasses.

Taking cues from existing conditions, the Arnolds created open-air “rooms” defined by surrounding small-scale buildings. Despite the unruly overgrowth, they envisioned a protected courtyard framed by the L-shaped house near the back of the lot and the former freestanding carport (long ago reincarnated as a 120-square-foot utility shed) at the front. Miraculously, the ancillary structure had proper permits for electricity and plumbing, and so, Hadley explains, “we were able to leverage a little house into a small home with a tiny outbuilding and a huge outdoor living room.” Eight months of the year, they cook, dine, and entertain outside.

Though a heavily trafficked road runs perilously close to the neighborhood’s houses, the Arnolds have effectively removed their property from the automotive realm by inserting a wall of burnished concrete block along the street front. Creating a surprisingly cloistered and serene refuge in the landscape (you completely forget the road is even there), the division makes the burgeoning canyon wall the prime backdrop. This safe harbor allows the couple’s young daughter, Josie, to run free outdoors with her playmates and a menagerie of pets.

From inside the light-filled house, you feel immersed in the landscape, completely removed from urban encroachments. Minimally furnished with antique, mid-century, and modern pieces, the interior offers an open living-dining-kitchen area, two bedrooms, and a pair of bathrooms. The small ancillary structure houses a workspace, storage, a washer-dryer, earthquake provisions, and a place for Josie to draw and paint.

During construction, when the house was still roofless, Hadley and Peter mused: “Let’s stop right here: open to the sky.” They added a cap, but modified it to preserve that expansive quality. When camping out, the Arnolds prefer to sleep under the stars without a tent, and when they’re home, they now enjoy skylights, which account for almost 20 percent of the roof surface. Lying in bed or in the tub, they watch fleeting cloud patterns, the moon’s phases, the constellations, and an occasional meteor shower. “When you live in a canyon, your days are short. The sun sets early against high horizon lines,” Hadley points out, “so it’s a gift to have this kind of light, these framed views of the sky.”

Not surprisingly, these environmentally attuned architects made their house and its grounds “as green as we knew how,” says Hadley, citing energy and water issues as “fundamental drivers” behind the design. Instead of air-conditioning, the home offers year-round comfort through cross ventilation and operable skylights (in the bathrooms) that function as thermal chimneys, venting hot air in warm weather. And an integral photovoltaic system not only meets the family’s energy needs (even heating the interior in winter via an electric radiant slab), but it also generates a surplus that the owners regularly feed into the city grid, selling excess electricity to the utility company.

“Equally progressive,” adds Peter, all the site’s rainwater is “allowed to percolate back into the water table, into the canyon’s underground stream, reducing runoff.” The gently sloping roofs, drought-tolerant plantings, and site-integrated dry wells are all key to this enlightened water management.

“And, of course, we recycled wherever possible,” says Hadley, pointing out materials they salvaged from the site’s previous building, including redwood planks, Douglas fir beams, and brick pavers: “Even the sawdust created during construction went into the grounds as compost.” And the oak bench outdoors, she explains, is a pew from a small summer chapel in Rhode Island, where she and Peter were married. “Our wedding was the last event before the parish sold off its fixtures and moved to another location. So my parents bought the pew and gave it to us for our first anniversary.”

A few steps from the benches, just inside the front door, stand two wooden statues from New Mexico: Saints Francis of Assisi and Paschal Baylon. Francis is thin and austere, the patron saint of restraint and simplicity; he is the environmentalists’ folk hero, “doing more with less,” the owners explain. Meanwhile, Paschal, a chubby, spoon-wielding cook, is the patron saint of hospitality and abundance. (The Arnolds are also talented in the kitchen.) “It’s a fine balance,” says Hadley. “Alone, Francis might seem intimidating, if admirably rigorous, while Paschal’s a bit indulgent, if more fun. But together they feel complete. As we see it, the purpose—and beauty—of restraint is to give rise to abundance.”