When architects Milena Karanesheva and Mischa Witzmann—the married couple behind Paris-based Karawitz Architecture—decided it was time for more space, they knew that they’d have to move their private lives outside of the French capital. After much research they settled on the small town of Bessancourt, about 17 miles northwest of Paris, because it offered an easy train ride into the city and a five-minute walk to the Montmorency Forest, ideal for their two young kids. But as for the house they’d live in, as Karanesheva puts it, “We wanted to use the opportunity to experiment.”

They commenced building in 2008, with German Passive House standards as their sustainability polestar. By construction’s end they had created a 1,733-square-foot home that uses only 4,200 kilowatt-hours per year—about a tenth of what a conventionally constructed house in France might use. With no other means of heating or cooling than those generated by the structure—a tenet of Passive House design—the new home is modeled on the French country dwellings of the area. Regional aesthetic codes also made their presence felt—out went any plans for a terraced roof, in came the barnhouse slope—but the resulting bamboo-clad abstraction of a farmhouse makes a strikingly modern addition to the rural landscape.

Though there are now more than 20,000 Passive Houses worldwide, when the Bessancourt abode was completed, it was just one of a few in France. And in an effort to further spread the green gospel, Karanesheva and Witzmann have hosted many open houses for guests (including the mayor of Bessancourt and visitors from 20 countries) interested in learning more about the unusual structure. Three years later, Karanesheva smiles when she says, “The neighbors just covered their roof with photovoltaic panels.”