THE HOME'S DOUGLAS fir siding was harvested from a forest 30 miles away, and the blocky master-bath wing is sheathed in untreated, cold-rolled steel, one of the most recyclable materials available. The concrete floor serves as a heat sink that absorbs sun and radiates it out at night. Nave built the soaker tub out of redwood reclaimed from a nearby barn and salvaged the greenhouse's floor-to-ceiling windows from the old Livingston post office. The greenhouse supports citrus and succulents and, at night, the couple's pet mallards, Thibideau and Boudreaux, who spend their days outside in a duck pond replenished by roof runoff.

But the greenest stuff is what you can't see, like a spray-in, open-cell foam insulation called Icynene—so benign, Nave claims, "you can eat it"—and an elaborate water-catchment system that harvests some 14 inches of rain annually off the butterfly roof and uses it, along with gray water from both bathrooms, to irrigate a riparian garden of native grasses, willows, and aspens. Twelve solar panels provide up to 40 percent of the compound's power on sunny days; the rest comes from the grid. And this spring, the couple plans to install a geothermal heating system that will pipe liquid heat from six feet underground, where the earth's temperature hovers at a stable 50 degrees year-round, and warm it to 160 degrees to provide the home's hot water and, in winter, radiant heat in the floors.

As with all sustainable strategies, the Ryker/Nave system does not run itself. Human interaction is part of the package—which, the couple believes, makes it all the more green. "If you want to live in a passive-solar house, you have to open windows. You have to participate," says Ryker. "Sustainable design is about creating a place that allows you to interact with the environment, not shut yourself off from it."

Of course, it's also about making a house that feels good inside. Even on this gray and unwelcoming day, the house is snug and inviting, with just the right combination of light and texture, scale and contradiction: exposed wood against polished concrete; airy, open kitchen funneling into a bowling-lane-narrow entrance hall bookended by tidy private alcoves; square north-wall portholes opposite floor-to-ceiling south windows streaming with sunlight.

"A professor once told me that the best place to learn architecture is where there is none," says Nave, who credits Buckskin Gulch, a 15-mile-long sandstone slot canyon in southern Utah, as an inspiration for all his designs. "If the most beautiful space you've been isn't architecture, but you can somehow translate it and then make something that begins to approach people in here"—he taps his chest—"that's not intellectual. That's awe."