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Early revelations about building a passive home

Marc Lefkowitz  |  04/22/11 @ 2:00pm

The passive house being built at the Cleveland Museum of Natural History is a vital part of the nationally touring climate change exhibit coming to the museum this fall; vital in that it addresses solutions. It does so by tapping locals to answer, "what do homes need to be like in the next generation?" project architect Chuck Miller asked a Northeast Ohio Green Building Council workshop this morning. (Since homes account for 27% of our carbon footprint in Northeast Ohio, it's more than a rhetorical question).

The team that is building the PNC SmartHome shared what they've learned so far as they stood with 30 architects and construction managers inside the house frame. The extra thick insulated panels were applied to the outside of the 2x6 interior walls this week and wrapped in a barrier paper to form a seal so tight that the home will have an 'ERV', a pump system that senses when fresh air is needed (during seasons when windows are closed). Flexible, white PEX tubes snaked through the open rafters and will connect to a unit that warms or cools air first by running it through a tube in the ground and further with heat coming off appliances, bodies, showers, even the heated towel rack!).

Yes, there's a premium, ranging from 10-20%, to build a house that will be 90% more efficient to heat and cool. Not using a furnace should pay down those first costs within ten years, said passive house consultant, strawbale home builder and a NASA fuel cell scientist Mark Hoberecht.

"Part of the premium is we're introducing this science and building technology to Ohio," said Miller, principal at Doty & Miller.

Cost would be less if and when the technology isn't so new (to the U.S.), he added. For example, the triple-paned windows being used here are manufactured and shipped at considerable expense from Germany. Meanwhile, Europe has built 25,000 of these 'passive homes' since the first one was built in Germany in the 1990s.

"Europeans will tell you, Passive Homes aren't as much about energy savings as how comfortable they are to live in," Hoberecht said.

The European Union has agreed to set new home construction to the Passive House standard after 2015. That signal from government jump started the private sector, Hoberecht said. It's why there are 40 window manufacturers in Europe who meet the Passive House standard ? and none currently in the U.S.

Ed Shank whose company is installing the air pump agrees the cost isn't in the installation; it's in the shipping of the ERV from overseas. The flexible tubes are cheap and even though he hadn't done a system quite like this, the learning curve was two hours and running the tubes took him one and a half days, he said, with the bill for the two heat pumps, the ERV, and the labor totaling $20,000.

Miller says he hopes the SmartHome, along with the handful of passive homes being built in the U.S., plus the homes built to standards like LEED and Enterprise Green Communities send a signal to U.S. manufacturers.

"What's been a revelation for me is the simplicity of this (building) system," Miller said.

New policy-including Cleveland's green building requirement for residential construction (to receive city finance or a tax abatement, new and rehabbed homes have to meet one of three third party certifications)-could help spur local interest in green homes and possibly even new domestic manufacturing. The structural insulated panels being used on the SmartHome are already being made near Pittsburgh. (It is possible to use them as interior walls instead of applied to the outside as they are on the SmartHome). The advantage of using the SIP, which is 6 inches of foam between two sheets of plywood, as insulation is it reduces air movement between the walls and the outside to almost nil. Walls that achieve high "R" values (these will be R-50 instead of the standard R-15), and the triple-pane windows are not required to get to Passive House standards, said Hoberecht, who 'modeled' the home's energy use on a computer. But without them, you have to find another way within the building 'envelope' since Passive House really prioritizes a super insulated core above using more expensive technological means to reach those 'factor of 10' reductions in heating and cooling loads.

Photo taken April 15, 2011. Designed to function without a conventional furnace, PNC SmartHome Cleveland will use 90 percent less heating energy than a typical home. It will be constructed using sustainable materials and furnishings, advanced stormwater techniques, healthy housing techniques and biophilic design to connect occupants to nature. Three key elements that distinguish "passive house" structures from typical houses: high levels of insulation, with walls more than 12 inches thick; a carefully sealed building envelope with minimal air leakage combined with efficient heat-recovery ventilation for superior indoor air quality; and ultra high-performance windows-at least double-paned and typically triple-paned. The result is a quiet, comfortable home with no drafts, no cold spots and extremely low heating bills.

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