Nestled on an ultra-steep infill lot near downtown Mill Valley, Calif., the Hillside House was designed to work in concert with the parcel’s topography, as vertically connected spaces interplay with an abundance of covered porches, decks, and balconies to form a dwelling that is as in tune with nature as it is tied into it.

Telescoping doors provide seamless transitions from indoors to outdoors, which the judges praised for making the house seem larger than its 2,116 square feet suggests. Even the master bathroom makes use of the surrounding trees and view: A glass wall separates the indoor shower from an outdoor bathtub, transforming an “intimately scaled bedroom and bathroom into a majestic space,” says project designer SB Architects.

With nearly 20% below grade, the LEED-Platinum home reaps the ground’s natural insulative benefits, while the integration with the exterior allows for abundant daylight and natural ventilation; the layout also provides optimal positioning for the roof- and trellis-mounted 3.75-kW solar arrays. Spray-foam insulation, energy-efficient appliances, water-conserving fixtures, FSC-certified lumber, and zero-VOC paints are just a few of the home’s numerous resource-conserving features.

Wood siding and beams combine with metal accents and purposeful symmetry to lend a rustic yet sophisticated feel to this “modern cabin,” as it is described by architect and homeowner Scott Lee, AIA, while locally crafted and sourced elements, including recycled-content ceramic tiles and custom benches made from fallen tree trunks, support Lee’s desire to highlight sustainability as well as the town’s artistic roots. Interior designer Erin Martin repurposed chalked-up, discarded scaffolding boards into one-of-a-kind stairwell walls and transformed buoys from Washington’s Puget Sound into vibrant pendant lights.

“It’s comfortable and familiar because of the palette of materials,” says Lee, “but it appeals to our sense as designers because [of its] modern elements.”

Windows: Fleetwood / Doors: NanaWall / Siding: EcoStucco; Western red cedar / Manufactured stone: Eldorado Stone / Insulation: Bay Systems / Appliances: Whirlpool; Jenn-Air / Countertops: Concreteworks / Cabinetry: New World Millworks / Kitchen Faucets: Kohler / Bath Faucets, Showerheads: Kohler / Toilets: Kohler / Flooring: Plantation Hardwood / Paints& Stains: Mythic; Penofin Verde / Interior Lighting: Bruck; Luminas / Exterior Lighting: Hadco; B-K Lighting / HVAC: HVACQuick; Fantech / Home Automation: Colorado vNet / Alternative Energy: Solar City 

Click here to see all 2010 EHDA winners.