IT'S HARD TO BELIEVE that Charles and Peg Fate, the owners of this 6,000-square-foot passive solar home, ever lived in a classic brick Colonial. But when architect Robert Boras first talked with the couple, they were clear about what they wanted: an easy-to-maintain, sun-filled passive solar contemporary home.

Do they ever miss the traditional homestead? "Never," says Peg Fate from her all- white kitchen, where window-filled rooms face south, tiled floors retain heat and the northern exposures are windowless. In summer, fans with a built-in thermostat pull hot air out of the house. In winter, the couple rarely use their heat pump because the house retains the sun's warmth so well.

While the overall design was left to Boras, the couple had a number of specific requests: a large kitchen where they could eat and entertain, separate entrances and separate rooms on the ground floor for their two teen-age children and a master bedroom suite distinctly removed from the children and their friends.

Boras pulled these needs together in an all-white sculptural home on a hillside overlooking farmland in Davidsonville, Md. The central organizing form is a three-story staircase topped by a massive skylight. At the base of the stairs is a hot tub; at the top, the master bedroom suite.

Necessarily, the house has a completely different feeling in the open and windowed front (see top photo at left) than in the back, where broad expanses of white stucco walls shield the house from cold northern winds. It is a house that can be understood only from one vantage point -- the sun's.