For Hunter Duplantier, the futuristic-looking house that went up last winter on the edge of the University of Louisiana campus in Lafayette stood out among its traditional-looking neighbors. It’s built like a loft, tall and boxy, with a flat roof and oddly placed narrow windows. But the most unusual attributes of the home were the ones he couldn’t see.

The building is the first in the southern U.S. to achieve official certification as a “passive house.” As such, it needs a mere fraction of the electricity it takes to run a conventional home of comparable size. Once it was completed last spring, Duplantier and two other architecture students enthusiastically volunteered to rent the place and monitor its performance. They moved in during finals week, embarking on an experiment in low-energy living that simultaneously harkens back to the super-insulated-house movement of the ’70s and provides a look at how we all might live in a peak-energy future.

“We were just in awe, just overwhelmed with information at first,” Duplantier says. After spending a record-breaking hot summer there, he reports, the home has “held up pretty well so far.”

The 1,200-square-foot home is one of a growing number of passive houses being built around the country in sizes and architectural styles as varied as the climates where they’re situated. A Maryland developer is putting up a 4,400 square-foot McMansion designed to perform like a passive house but look like an American foursquare, those faux farmhouses popularized a century ago thanks to mail-order construction kits sold in the Sears catalogue. In New York City, meanwhile, another architect has embarked on the first-ever passive retrofit of a genuine century-old townhouse.

“It was a challenge,” says Jeremy Shannon, the vice president of Prospect Architecture, P.C., who convinced a couple of Brooklyn homeowners to go passive instead of doing a run-of-the-mill retrofit of their Park Slope brownstone. “We both agreed,” he says of the owners, who want to remain anonymous, “This is going to be a real extreme challenge. Let’s see if we can do it.'”