The rough-hewn rock and heavy timber exterior of this 4,800- square-foot townhouse is only fitting for its mountain location in the historic mining town of Ketchum, Idaho. But rather than continuing the same aesthetic inside, the interiors offer a serene counterbalance of clean lines and polished surfaces. Radiant-heated cast concrete floors and fireplace surrounds are inlaid with fossils, semi-precious stones, mosaic tiles, and copper accents.

“Because the building is nestled into the mountain, most of the windows are in the front of the building, and some areas of the house do not have natural daylight,” says designer Fu-Tung Cheng. “It was important to use finishes that would add warmth and light, while reinforcing a sense of grounded mass against the backdrop of the mountains.”

To keep the concrete forms from becoming too cold, the designer introduced complementary materials and textures, such as warm wood finishes and custom light fixtures. Green products in the mix include low- or no-VOC paints and sealers, Plyboo flooring and wall coverings, composite wood cabinets, natural artisan plasters, and clean-burning ethanol fireboxes.