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Innovative Passive House: Uber Haus

Posted by Green Builder Staff

Aug 26, 2014 11:19:09 AM

 DUBBED "PASSIVE HOUSE IN THE WOODS", this project takes energy efficiency far beyond the experience of most residential builders. It’s a bleeding edge design, a strikingly modern structure that produces 65% more electricity than it needs. It also has an interesting back story.

“The client’s wife was ill with cancer as we were planning this home,” notes architect Tim Delhey Eian.
“She passed away before construction began, and we ended up changing the design to a much more vertical plan.

“We chose ICFs deliberately, as a pretty fail-safe construction method,” he adds. “I had a good grasp of Passivhaus concepts, because I grew up in Germany and completed the training there.”

Deep Science
Although the systems in this home are familiar, this project takes them to a higher level. The ICFs, for example, extend below grade, and are augmented with a commercial-grade EIFS system that includes 11” of EPS foam above grade—making a wall 22” thick with an R-value of 70.

“We tried to get the North American branch (of Sto Corp.) to provide the details we wanted, but the deal fell through,” the architect notes. “They only offered this version of EIFS in Europe. It puts all of the water management on the exterior. They’ve now started offering it in the U.S.”

The flat roof includes 14” of polyisocyanurate foam, achieving R-95, and the windows and doors, imported from Germany, are triple-pane, low-E coated, with insulated frames. They have an installed R-value of 8. By comparison, a typical wood or vinyl-framed, dual-pane, low-E window achieves only about R-2.

The slab also sits on 12” of EPS foam (R-60), and the garage doors are insulated as well, so the overall heating demand for the home is extremely low. In fact, it has no furnace and no fireplace, despite the cold climate. The home, designed for a heating load of just 3,000 W, relies on passive solar plus a modest ground loop geothermal system, with a back up of electrical floor mats from Nuheat. A super-efficient HRV provides ventilation to the whole house, with minimal loss of BTU.

Along with the 4.5 kW PV panels, the house has a 40-sq.-ft. hot water solar collector that provides 90% of the home’s hot water demand. A small electric hot water heater provides the rest.

Ongoing Improvements
The architect notes that by monitoring the home’s performance during the first year, the team was able to identify hidden energy wasters. “For instance,” he says, “we now know that the well pump was using a lot of energy—12% of the home’s consumption for a year. That was easy to improve.

“At the same time,” he adds, “some of the appliances out-performed our original estimates, in part because they weren’t used as much as expected. But we’re now extrapolating from the lifestyle impacts.”

Too often, notes the architect, home owners look at the aspects of a home that are not important—things that “are really going to go down the drain.” Not so, with this house, he says. It’s a project that ultimately gives the owner freedom—so “he won’t owe monthly bills to anyone.”


  • Framed with steel and built with 11” ICF walls, plus an 11” EIFS system, this home meets or exceeds Geman Passivhaus standards.

  • The plan keeps windows to a minimum on every face except the southwest (shown on p. 41) but where glass is present, it’s triple glazed and gas-filled, offering three times the R-value of a typical dual-paned low-E window.

  • On the interior, the team carefully selected KCMA-certified  cabinetry, ...

  • ...low- or no-VOC finishes and American Clay wall coating systems.

  • Built-ins and eco-sensitive furnishings ensure that the home’s indoor air quality isn’t compromised. All lighting is CFL or LED.

  • A grid of steel exterior stairs provides private access to upper floors and leaves more room indoors for living.

  • The home has no furnace or boiler. For passive solar backup, it relies on a 600-ft. geothermal loop and electric in-floor heating mats. The mats supply about 3kW, or 10.5k BTU—enough to heat the home on the coldest winter night.

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Topics: ICFs, solar, solar hot water, 2011 Green Home of the Year Awards, passive house

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