Arkin Tilt Architects finessed one of the trickiest livability issues of a Passive House, and the judges applauded. “This is a Passive House that actually has windows,” one said. “I could see it fitting into a lot of different neighborhoods.”

The simple envelope helps to ensure a tight air seal; but to maximize sunlight, the house changes sectionally as you move through it. A south-facing clerestory over the two-story central living space makes the most of the limited openings. Balancing that light source on the north are three operable skylights above the stairwell and a window at the landing, which also create a thermal chimney effect.

This house is chock-full of resource-sipping innovations, two of which were permitting firsts for Palo Alto: a kitchen sink greywater system and urine-diverting toilets. Additional measures such as an air-to-water heat pump that heats domestic water and radiant floors, heat recovery from the shower drains, and rainwater collection made the house a local landmark that’s been toured by more than 800 people.