Passive House Comes to America

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Posted: Wednesday, January 16, 2013 5:50 pm

LEED, the gold star for environmentally-friendly buildings, is looked upon favorably by local governments, many of which have adopted policies to encourage its use. While LEED addresses a breadth of goals from materials to indoor environmental quality, land use and energy, there is an emerging energy standard that also delivers amazing results.

Those familiar with the rigorous German standard say Passive House results in the highest energy savings for buildings, with HERs index rating in the low 30s, compared to Energy Star and LEED rated buildings in the 50s, and new houses built using conventional code at 100. Zero net-energy homes come in at zero or produce more energy than they use.

Passive House homes do so well because they focus on one primary end goal – to reduce the energy demands of a building. By dramatically increasing insulation and setting limits on air infiltration, then introducing heat recovery ventilation, Passive Houses minimize heating loss in the winter, so much that it can eliminate the need for a boiler or furnace, running on heating sources as small as a hairdryer. Passive House homes also use insulation, air tightness, and shading to dramatically reduce cooling loads as well.

“LEED is very ambitious and it looks at a huge list of issues. It looks at air quality, water, use of land, how materials are sourced, all the environmental impacts,” said Laura Nettleton, president of Thoughtful Balance, a green architecture firm based in Pittsburgh.

So when her firm also began focusing on Passive House certification projects, “it wasn’t like we threw out the lessons of LEED,” she said. Both can be used together, but when it comes down to certification, she prefers Passive House.

One factor is cost. Her current project, the retrofit of the McKeesport YMCA into 85 Single Occupant Units, is estimated to cost $20,000 for both certification fees and a third-party consultant who handles quality control during construction. The developer, Pittsburgh-based ACTION-Housing did not cost out the LEED certification for this project, but a previous project half its size was estimated at $70,000.

While Passive House certification costs may be more affordable, construction costs may still be a challenge due to much thicker insulation, the airtight envelope, and the heat recovery ventilator, said Vivian Loftness, professor of architecture at Carnegie Mellon University.

“The benefit is that energy bills are a fraction of what they would be in a standard home for the next 30 years,” she said, and emphasized the need for Energy-inclusive Mortgages, the emerging ‘mortgage plus energy’ financing, that reflects the true cost-effectiveness of the initial investment. In these mortgages, the loan reflects the full carrying costs over the life of the mortgage, not just the value of the house.

Loftness already has a LEED AP credential, but has begun the coursework and take-home exam for Passive House as well. She believes professionals should have both credentials, and pursue ongoing learning to lead in the design, construction and operation of high performance buildings.

When the founding organization, Passivhaus Institut in Germany, and Passive House Institute–United States split in 2011, the educational and certification systems began to diverge.“The leadership in Europe had not advanced the standard for the unique climate conditions and construction standards in the U.S.,” Loftness said.

The principals of Passive House on both sides of the Atlantic are rock solid, but the execution is different, said Mike Knezovich, communications manager of PHIUS. Working with the Fraunhofer Institute and Oakridge National Labs, the Passive House software has been significantly refined for the U.S. context, including the measurement units. Tackling humidity which causes mold and mildew issues in certain states that don’t exist in central Europe is another advance.

“We tried to adapt things to the reality here on the ground in the states and in Canada and it just kind of built,” he said. “There’s some hard feelings. They really did not approve of our Americanization of the Passive House idea.”

The U.S. version of the certification is known as PHIUS+. It differs from the original certification in that it offers a more palatable package for the North American market–a HERs index score from RESNET can be used for applying for tax credits or an energy inclusive mortgage. The other two benefits are designations, namely Energy Star for Homes (version 3) and Department of Energy Challenge Home.

The parties involved can include the Passive House consultant who reviews the plans and energy modeling, the certified Passive House contractor, and the Passive House rater who certifies the building. As the U.S. certification package includes a HERS index score, a home energy auditor from RESNET conducts quality assurance checks in the form of site visits during construction and at the end. The RESNET auditor checks all the plans and construction according to RESNET standards.

Knezovich estimates there are about 150 certified Passive Houses in the United States. Today, documenting the energy performance of completed projects will be key to establishing just how well it works.

Nonprofit ACTION-Housing developer Linda Metropulos, senior real estate officer, is willing to share data on the first Passive House in western Pennsylvania, a new 1,800 sq. ft. single-family home designated as affordable housing. So are six other multifamily developers in different regions of the U.S. who have formed a consortium experimenting with Passive House standards.

“If you have people who are willing to do the work, then let somebody track the data, it's really a great situation,” said Nina Baird, adjunct assistant professor at Carnegie Mellon’s School of Architecture.

Tracking the energy performance of Passive Houses will also contribute to her efforts to study energy retrofits in over 8,300 units of multifamily affordable housing in Pennsylvania. The Pennsylvania Housing Finance Agency has required the sharing of energy data – one year before and five years after – for every upgrade financed by stimulus funds, she said.

“They’re willing to provide the energy data after it’s upgraded, so we’ll be able to see how the apartments are performing,” she said, particularly the savings and if it is worth a greater investment up front.

The shared goals of LEED, DOE and Energy Star’s HERs, PassivHaus Europe and Passive House USA are to achieve the highest level of energy performance possible. The ongoing development of metrics, tools, and curriculum to enhance our knowledge of regional high performance solutions is critical.

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