Eleven years ago, a California couple's passion for the environment had them set out on a journey to engineer a fully net-zero home. And today, that house has come into fruition and has gained a multitude of praise. The 0.84 acre piece of land was bought for $2.675 million in Hillsborough, and was converted into a greenhouse oasis. The avid environmentalists were adamant about building a structure that was different from their neighbors and close to their hearts. The couple, Sally Lui and Bay Chang, hired a San Francisco based design firm, Aidlin Darling Design, to help bring their vision to life. The main architect on the project came to call the home “House of Earth and Sky,” delivering the couple with an exponentially green-house. The two had ample knowledge and experience with LEED, a national standard for green buildings. A practice that was implemented into the design of the home, that eventually received a platinum certification. 

Ms. Lui had a strong desire for a drought-resistant garden, a prominent theme throughout the house. Peter Larsen, one of the architects, recalled the couple falling in love with the base material, a compact soil used in many ancient and now contemporary construction. Larsen and Aidlin formed a design model to show the couple before breaking ground and building upward. The design included–an ecological and durable all-electric design for the glass walls and rammed earth; clerestory windows and blackened wood cladding; and linked public and private zones. 

“It was a diagram for sustainability. The forms all had a function,” stated Aidlin. The couple confirmed the design in 2015, after Landscape Architect, Ron Lutsko and Interior Designer, Gary Hutton were brought onto the team. In itself, the home was a green idea, intended for intergenerational living, connecting the outdoors inward. The living spaces were equipped with LED pendants and nontoxic, or low-VOC material finishes. The 18-inch-thick walls were constructed from the soil compact material approved by Lui and Chang–it's a blend of sand, earth, and Portland cement. The walls are low maintenance, rot resistant, and contain thermal mass that shields the interior from external heat. This allows the house to ditch the use of standard heating and cooling systems. 

The roofs above the living spaces, guest house, and pool area are asymmetrical butterfly style that sit at an angle for optimum sunlight absorption for electricity conversion. The roofs also serve as a natural rainfall irrigation system, catching the rain and storing it in an underground cistern to be used throughout the landscape. A steel spiral staircase sits within a three-story tower, designed to have a passing stack cooling effect, ventilating out the heat and pulling up the basement’s cooler air. 

“I am an engineer who loves spreadsheets. The goal was to be net-zero energy, and I was relieved the solar numbers met the goal. It all looks natural. I can see a ‘meadow’ and the hills on one side. In the other direction, I look at a ‘forest’ of trees. And this wonderful house is simply a conservation cipher for others to decode,” stated Ms. Lui.