The Tightest Home in North America

A few miles north of Bemidji, there’s an old-world mini Bavaria: A cluster of white stucco and brown-timbered buildings that surround a quaint central fountain. The street signs are auf deutsch, schnitzel and sauerkraut are on the menu, and the speaking of German is strictly enforced. When this Concordia language village, a German immersion camp for kids, needed a new dormitory, however, the staff voted to promote a modern vision of Germany rather than further perpetuate this idealized version of the past.

Enter Eddie Dehler. Lured from his native Germany in 1987 to work as a language teacher at the youth village, Dehler tapped into his environmental-studies background to initiate the construction of North America’s first certified Passivhaus: an airtight, super energy-efficient structure that utilizes passive solar and geo-thermal energy for year-round temperature control.

The project began in the fall of 2005, when special triple-pane, heat retaining, argon-filled windows from a factory in the Black Forest were flown in. The roof was covered with dirt and seeded with purple sedum flowers that help retain water, avoid erosion around the house, and provide extra insulation.

The project was not inexpensive. Concordia Language Villages built Dehler’s five-thousand-square-foot modernist Bauhaus vision at a cost of around $1.3 million. But owners of these ultra-green buildings are destined to save on utility bills. Beneath the house, a tube filled with food-grade glycol-water solution runs two hundred feet into the earth. This creates a constant-temperature mixture that gets pumped back up to the house and into a reverse refrigeration system, thus providing low-cost heating and cooling.

The house still uses some electricity. “It’s on the energy grid—so we could [improve efficiency by installing] photovoltaic solar panels on the roof,” Dehler said. With them, Dehler said, the building would actually produce more energy than it consumes.

In order for the house to be certified as an authentic Passivhaus, the structure had to be assessed to determine whether it met the German government’s strict standards. Gary Nelson, president of the Energy Conservatory, a local building-performance testing service, came to the language village to conduct something called a blower-door test.

“We created a negative pressure in the building to test every wall and window for air leaks,” Nelson explained.

Heating the building “requires less than one watt per square foot. A typical toaster or hairdryer uses 1,500 watts, so one of these could heat a 1,500-square-foot Passivhaus,” Nelson concluded. In the end, the house was deemed twenty times more airtight than required by German standards.

Using the Passivhaus (which officially opened in July 2006) as an instructional tool, the German camp now offers a four-week environmental credit program for high school students. Inside the big blue box with giant southern-facing windows, twenty-eight campers can learn about the first Passivhaus (built in Darmstadt, Germany in 1990), and about how passive solar heat, when combined with super-insulation, makes for one of the most energy-efficient buildings ever made.

Dehler proselytizes visitors to what he calls the “tightest home in North America” in hopes of spreading the German ideal for sustainable living, proclaiming that the extra money spent to reach these strict standards — around twenty thousand dollars — will be recovered through energy savings in as little as eight years.

“The Passivhaus uses about ten percent of the energy of a regular house,” Nelson, the house-tester, said. “The six thousand of them already built [in Germany and Austria] use the same amount of energy as six hundred regular houses. Why can’t we do that in Minnesota? If we made enough of them, we could shut down the Monticello nuclear power plant.”