With its bold, upswept profile, the roof gives this otherwise simple house its distinctive character. But those curves are not merely for show. The concave forms are integral to the dwelling’s self-sufficiency because they act as water collectors and sun protection. When rain hits the roof, it runs down into holes punched into the valleys created by the tilt of the corrugated-steel sheets. Underneath these holes, which are too small for leaves to penetrate, the water collects in a concealed gutter and is piped down the side of the house and underground to the nearby water tanks. Using a combination of computer technology and onsite observation, the architects calculated how far the main roof would have to overhang the north elevation to let in as much low winter sun as possible, while shielding the interior from the more extreme summer sun. The nearly 13-foot-high expanse of glazing that embraces the views really needed protecting—and the four-foot eave created by the sweep of the main roof does the job well.