Page E1.2 . 11 January 2012                     
ArchitectureWeek - Environment Department
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Passive House Divided


The Passive House certification is a strict system that involves meeting various design standards and passing a final blower door test — in which all the doors and windows are closed and air is pumped from the structure to measure its airtightness.

The certification process starts before a project breaks ground, with a review of drawings that must meet a design checklist. Once built, a Passive House-certified building cannot have more than 0.6 air changes per hour (ACH) when the building is depressurized to 50 Pascal pressure during the blower door test.

Annual heat requirements must be no more than 15 kilowatts per square meter per year (1.4 kilowatts per square foot per year), and primary energy needs cannot exceed 120 kWh/m2/year (11 kWh/ft2/year).

While some other specifications vary depending on the climate where the house is built, the windows should have a U-value of at least 0.8 watts per square meter-kelvin, while the ventilation system must recover at least 75 percent of the outgoing heat (according to PHIUS).

When built to these specifications, a Passive House building typically needs little more than the body heat of the people inside to keep temperatures cozy. Such buildings can have no conventional heating system, as Lloyd Alter noted in a 2008 TreeHugger article about the Urbana house Klingenberg built in Illinois in 2003, the first certified Passive House in the United States.

As Alter reported, "There is a 1000 watt toaster coil in a duct, in case supplementary heat is needed (1000 watts! 10 lightbulbs can heat this whole joint when it is 10 degrees below zero!) but last January the electrical bill (for everything) was only thirty-five bucks."

Growing up in Germany, Klingenberg of PHIUS was already acquainted with the superinsulated building system and had studied under Feist at the Passivhaus Institut in Darmstadt. After completing a master's degree at Ball State University, Klingenberg designed the Urbana house for herself, as a proof-of-concept for Passive House in the United States.

Klingenberg participated in promoting the Passive House standard in the U.S. by translating some of PHI's training documents into English, developing a cordial relationship with Feist, who eventually made PHIUS his institute's sole certifying body in this country.

Between 2007, when PHIUS started training architects and consultants and shepherding construction projects through the certification system under a license from Feist's company, and August 2011, when PHI suspended its contracts with PHIUS, 24 buildings in the United States earned Passive House certification.

The PHIUS number is miniscule compared to the count of buildings in the U.S. certified under other, less-strict U.S. green building standards, such as the U.S. government's Energy Star program, or the USGBC's LEED green building system, which counted over 10,000 total building certifications as of October 2011.

Two-dozen homes is a barely-symbolic drop in the bucket for the overall U.S. green building market, which has been growing much more quickly than conventional construction in recent years. In 2010, the total value of commercial and residential green building reached somewhere in the range of $55 billion to $71 billion, according to the McGraw-Hill Construction report "Green Outlook 2011: Green Trends Driving Growth."

But while Passive House is just getting started in the United States, more than 20,000 Passive House structures have been built and certified worldwide, according to the International Passive House Association (iPHA), a Darmstadt-based PHI affiliate tasked with interfacing with the Passive House groups around the world.

Most of those Passive House buildings are in Europe. More are expected as the European Union prepares to meet stringent new rules requiring new buildings built after 2021 to be nearly energy-self-sufficient.

According to Klingenberg, interest in Passive House seems to be growing in the U.S. as well, with nearly 100 candidate buildings in various stages of construction as of December 2011.


In her August letter responding to Feist's decision to sever ties with PHIUS, Klingenberg expressed surprise at the turn of events, commenting, "We used to be friends."

U.S. Passive House practitioners say they were denied the members' discount for the annual international Passive House conference in Hanover, Germany, in May 2011.

PHIUS communications director Michael Knezovich says that after May, things quickly got worse. "We had honest differences," he says, "but it went from talking to this sort of nuclear option with no sort of warning."

In Feist's August 17 letter outlining the reasons behind his company's decision to part ways with its U.S. affiliate, he wrote:

"Unfortunately, recent actions by PHIUS have culminated both in breaches of contract and good faith, unnecessarily reinforcing false divisions within the Passive House community. In light of PHIUS' disregard for its standing agreements with PHI, we are left with no other choice but to suspend all standing contracts. Evidence of PHIUS' certification of Passive House buildings without the requisite documentation has threatened the integrity of the Standard and forced PHI to terminate PHIUS' status as an accredited Passive House Building Certifier... Finally, PHIUS' introduction of a competing professional certification scheme as well as its refusal to honour existing contractual obligations has left PHI with no other option than to revoke PHIUS' authority to offer the International Passive House Designer exam. As Passive House is and will remain an international and open concept, we accept PHIUS' choice to "go it alone" and wish it well on its journey in the continued promotion of Passive House construction. It is our hope that one day, PHIUS can again cooperate with PHI in a fruitful, positive way. Until that time, we must make it clear that PHIUS may no longer rely on PHI's name and expertise to bolster its own image."

Klingenberg denies the allegations in the letter. PHIUS issued a public statement on August 18, followed by an 11-page response to Feist in which Klingenberg responded to the allegations and made counter-allegations, saying that it was PHI that had breached the contract, and accusing the company of making an "unethical" attempt to discredit her organization.

Feist responded on August 23 with a statement to the Passive House community elaborating on the disagreements over the contracts, and accusing Klingenberg of "publicly slandering PHI."

The series of cross-Atlantic volleys prompted one U.S. fan of the Passive House system to remark, "It was painful to hear all that dirty laundry."

The Quality Issue

In her August 19 letter, Klingenberg also acknowledged errors in the certification by PHIUS of a house in Ottawa, the first house in Canada to be Passive House-certified.

The building in question is the Rideau Residences, a duplex infill project designed by Vert Design. The three-story, 3,300-square-foot (307-square-meter) building was designed to meet Passive House certification, and also received a LEED for Homes Platinum certification. The building's well-insulated exterior brick and metal walls achieve an R-value of 22, while the windows are triple-glazed with argon gas between the panes, according to Vert Design.

The project's Passive House certification has apparently been revoked by PHI. When interviewed for ArchitectureWeek in December, Klingenberg attributed the erroneous certification to the learning curve faced in adapting the Passive House process to such a cold climate. She also indicated that the project had come under scrutiny in Germany after a Canadian Passive House consultant raised questions about whether it met the standard.

Ryan Abendroth, the certification manager for PHIUS, explains that the building had passed the blower door test, but other design issues were later discovered.

"The problem was twofold," he says. "First, the thermal bridge of a steel angle, which we had thought was detailed differently than it was in actuality. The second was that the shading situation was not comprehensively understood. Upon measurement after completion, it was found to be less sunny than modeled. Both of these changes worked to push the project out of the range of certification."

Problems with the Rideau Residences certification exacerbated existing tensions.

Sam Hagerman, president of the Portland, Oregon-based construction company Hammer & Hand, and also president of the national Passive House Alliance-US (PHA-US) — a nonprofit group closely allied with PHIUS in efforts to promote the building performance standard and principals — says the Europeans seemed to view their U.S. colleagues "almost with mistrust," a situation he chalks up to a wide cultural and philosophical divide separating the two continents and their building methodologies.

One of the seemingly pettier flashpoints was over a tool the Americans tacked on to the PHPP software to make it easier to convert meters, British thermal units, and other metric measurements to feet, kilowatt-hours, etc. (The spreadsheet software allows architects to calculate the energy consumption of a building before it's built.)

The characterization of this dispute differs between the organizations. In the August 23 follow-up statement from Feist — in which he alluded to PHIUS's recent conduct as "craziness" and accused the organization of seeking a Passive House monopoly in North America — he also wrote: "At no time did PHIUS have a contract to even sell PHPP, let alone to adapt it (no, this is not merely about imperial versus metric — PHI fully understands and supports the needs of American designers to use numbers with which they are familiar, and is currently working on a solution). Nothing has changed except for the fact that PHI has now demanded PHIUS discontinue the illegal sale and adaptation of PHI's property."

Klingenberg and other PHIUS officials report telling Feist, at a tense meeting in Innsbruck, Austria, in mid-2011, that PHIUS organization was pulling out of PHI's new International Passive House Designer exam and going back to the testing methodology used prior to November 2010.

The vast majority of PHIUS students who had taken the new PHI test had failed, setting off a new round of acrimony over whether the U.S. students were ill-prepared.

Tomás O'Leary, co-founder and principal trainer of the Ireland-based Passive House Academy, contends "most U.S. architects need to get reeducated in what influences building efficiency."

Klingenberg, however, says PHI ignored her group's feedback that the exam was too Europe-focused and didn't give enough weight to U.S. issues, such as making Passive House work in U.S. climate zones — including the problematic Deep South, where extreme humidity provides a design hurdle that central European architects don't have to worry about. In her August 19 response, she also suggested that a reason Feist broke with her group was to preserve revenue that his for-profit institute stood to lose if her group made good on its plans to stop administering the PHI test.

Meanwhile, the German institute says it is not abandoning the U.S. market. In fact, O'Leary's Passive House Academy, one of PHI's 32 accredited building certifiers worldwide, has now set up operations in the United States, offering Passive House consulting services and training courses in New York City and San Francisco in 2011, with plans to expand to other U.S. cities in 2012.

"We're doing everything according to the international standard set by the German Passivhaus Institut," says O'Leary, who says he expects other PHI-accredited building certifiers to also open offices in the United States as the market grows.

"It could end up with two movements in the United States. That would be a pity," he says. "But I put my money on the global movement."

The U.S. conflict isn't the first to roil the international Passive House movement. Much as PHIUS embarked on efforts to add third-party verification to Passive House to make it more like other U.S. green building programs, other international affiliates in Austria, Sweden, and elsewhere have also localized the Passive House approach in ways that haven't always been well-received by PHI.

RESNET Connection

The reference in Feist's letter to "PHIUS' introduction of a competing professional certification scheme" refers to PHIUS's affiliation with the Residential Energy Services Network (RESNET) — a relationship initiated in February 2011.

PHIUS saw teaming with RESNET as a valuable step toward removing obstacles to broader U.S. market acceptance of Passive House, and to improve opportunities for cross-pollination with industry labels that reward buildings for minimized ecological footprints.

RESNET is a nonprofit U.S. standards-making body that operates the HERS Index, a scoring system based on the 2004 International Energy Conservation Code.

Net-zero-energy homes receive a rating of zero on the HERS Index, homes built to IECC 2004 are rated at 100, and homes with even more energy consumption are scored over 100. A house under 3,000 square feet (280 square meters) built to the 2009 IECC standard is rated at 70.

Passive House buildings weren't getting as low a HERS rating as one would expect of buildings known to need as little electricity as it takes to run a hairdryer, and the PHIUS-RESNET partnership aims to improve the way HERS works with the Passive House standard to better reflect its energy performance.

PHIUS is also training RESNET's professional home-energy raters to carry out the full certification process for the newly launched "PHIUS+" Passive House certification, moving the field work out of PHIUS's hands, and thus providing third-party verification. PHIUS trained the first group of building raters from RESNET in December 2011.

The two groups plan to work together to harmonize their programs and streamline paperwork requirements for buildings submitted for both PHIUS+ certification and HERS ratings.

With more appropriate HERS ratings and a third-party verification, PHIUS+-certified buildings are expected to qualify for federal government tax breaks and other incentives available to low-energy homes — perks these ultra-energy-efficient buildings had previously been shut out of.

RESNET acceptance of value to PHIUS, and to many U.S. builders, because HERS ratings are widely recognized by other green building labels, including LEED and the U.S. Department of Energy's Builders Challenge, which has a EnergySmart Home Scale (E-Scale) based on the HERS Index.

Both PHIUS and RESNET express enthusiasm about their new relationship. "It's a great step because we need to speak the same language" among U.S. green-building systems, says Klingenberg.

RESNET executive director Steve Baden says the relationship makes sense for his organization because PHIUS, too, is focused on energy efficiency, which is increasingly a focus of the entire U.S. construction market — not just the green building niche.

"This all indicates the growing market force for energy-efficient, high-performing homes," says Baden, who doesn't expect the Passive House organizational schism to impact these plans for collaboration.

PHI in Germany was apparently not comfortable with the relationship between RESNET and PHIUS, perhaps, experts say, because third-party verification is not common in Europe, where buildings are built to last much longer than in the United States.

According to Hagerman, the Passive House Alliance-US president, and several others interviewed for this story, while Europeans generally construct their homes, schools, offices, and other buildings to outlive the builder, most new U.S. construction isn't calculated to remain standing more than a few decades. Given what many consider shoddier prevailing practices in U.S. construction, third-party verification is a big issue with buyers, government tax incentive plans, and officials writing new building codes and municipal ordinances.

Passive House in the U.S.

Klingenberg says the new independence of her group will not lead to compromise on the stringent Passive House rules. "We have the same checklist [as PHI], starting with the building science review," she says.

Knezovich, the PHIUS communications director, adds, "We looked around and said, 'Nothing has really changed except we don't have the blessing of the mothership anymore.' We're as busy as we have ever been."

What does the falling out mean for Passive House buildings which were previously certified by PHIUS?

"All buildings certified by PHIUS in PHI's name prior to the termination of PHIUS' certifier contract will of course retain their certified status so long as no irregularities regarding the certification itself are discovered," wrote Angela Espenberger, co-manager of the International Passive House Association, in an email.

For architects, engineers, and others who sought professional certification through PHIUS, PHI today recognizes only those individuals who passed the International Passive House Designer certification exam between November 2010 and June 2011, according to Espenberger.

That apparently leaves out most of more than 200 people who received the alternative 'consultant' status through PHIUS since the organization opened its doors about five years ago. These certifications are still honored by PHIUS, which is renaming its program the North American Passive House Consultant certification to differentiate its training from the international one.

U.S. builders who would prefer the imprimatur of PHI are free to work directly with architects and designers certified by PHI-accredited certifiers, including O'Leary's Passive House Academy, says Espenberger.

For two architects who have built Passive Houses, maintaining a commitment to high standards is about more than remaining in the PHI fold.

Washington, D.C.-area architect David Peabody says, "I'm thinking long-term it's probably better, with one caveat: Passive House [Institute US] cannot relax the standard at all. If we stick to the same model, it can't be anything but good." Peabody is currently working on his second house designed to Passive House specifications, and says he hopes to never again design a conventional home.

Corey Saft, who designed a Passive House in Louisiana — the first one certified in the Deep South — says it's unfortunate that two groups doing such "fantastic work" would have a falling out, but what counts is how the U.S. houses perform. "At the end of the day, whether [a building] makes a standard set in a foreign country is not what's important," Saft says. "It's the performance that tells the story."

Energy Super Star?

Meanwhile, according to Klingenberg, the new RESNET affiliation with PHIUS is a first step toward the goal of eventually incorporating Passive House energy specifications into LEED and Energy Star.

Klingenberg has been talking for years with Sam Rashkin, the longtime manager of the Department of Energy's Energy Star for Homes program, about how the two labels could work together. PHIUS and the USGBC have also engaged in discussions about how the Passive House energy standard could work with LEED.

Rashkin, who is now the chief architect in the U.S. Department of Energy's Building Technologies Program, says Passive House may fold nicely into the next iteration of the Energy Star system, expected three or four years from now.

"I'm looking for the research to tell us what is the sweet spot in terms of tightness and energy efficiency," particularly in terms of cost per energy-efficiency gain, Rashkin says.

He's been watching Passive House develop for several years and says he can envision adding that system's energy specifications as a new high end for Builders Challenge, which is Energy Star's current high-performance home construction standard.

"It's like a car wash with different levels of services," says Rashkin, explaining that a project could go just with a Energy Star rating, which would be like getting a wash; or opt for Builders Challenge, which would be more like a wash and wax; or opt for Passive House, sort of like going for the whole detailing shebang.

But first, he'd like to see Passive House become more like Energy Star, LEED, and other U.S. green-building standards by incorporating other environmental benchmarks beyond energy. One way to round out the standard, he says, would be for Passive House to make Builders Challenge a prerequisite. Beyond energy-efficiency requirements, Builders Challenge has quality requirements for building materials, requires use of low-VOC paints and adhesives, and demands proof that construction waste is minimized and recycled whenever possible, among other things. Klingenberg says the possibility of such a hybrid approach is exciting and could attract builders who might otherwise be wary about embarking on a project that must meet such a high performance bar in order to pass.

"[Passive House] is a very stringent standard that might break your heart" if your building falls short, Klingenberg says. "This way it's not the end of the world. You still get a HERS rating and energy subsidies" and may even qualify for another green building certification, she says.

Passive House Code?

Getting a green building system recognized in building code can propel rapid adoption. U.S. Passive House advocates are pushing to get the building standard recognized by state and federal laws.

So far advocates have had a smattering of success. For instance, Passive House supporters lobbied successfully in 2011 for a waiver recognizing Passive House in Oregon's "reach code," an optional construction standard for building energy efficiency that exceeds the state's mandatory code requirements.

According to Hagerman, differences in the European system — especially the lack of third-party verification — had hampered those efforts prior to the RESNET arrangement. He says it had been hard to convince local zoning boards and state and federal lawmakers to support a standard developed and controlled by a foreign country, but expects it to get easier now that PHIUS has parted ways with PHI. "There was no way that U.S. zoning authorities would adopt a system that needed to be approved in Europe," he says.

"We need to make this an energy independence movement that's native to the United States," says Hagerman.

New Connections

On January 9, 2012, the International Passive House Association announced a new affiliation with New York Passive House, a nonprofit group established to promote the certification system in that state.

"iPHA is committed to working closely with Passive House groups across the US and is on the way to establishing further affiliations with active groups throughout the country," according to the iPHA press release.

Andreas M. Benzing, a New York City-based architect who serves as vice president of New York Passive House, says his organization is not taking sides in the schism. "We work with everybody and are trying to stay out of it."

"What we decided to do is to stay neutral and accept both certifications [issued by PHI and PHIUS]," Benzing says. "At the end of the day, everyone should be able to build to a higher standard — that of Passive House."

That sounds right to ArchitectureWeek. With about 1000 times more buildings certified in Europe to the one standard that's likely to match lifetime performance requirements for buildings created today, the U.S. has a lot of catching up to do — no matter who is running the scoreboard.

Discuss this article in the Architecture Forum...

Christine MacDonald is the author of Green, Inc.: An Environmental Insider Reveals How a Good Cause Has Gone Bad (Lyons Press, 2008). She lives in Washington, D.C., and has written for The Dallas Morning News, Los Angeles Times, The Washington Post, and The Nation.   More by Christine MacDonald

Thanks to the Ecologic Institute for travel support for research and photography related to this article.



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Designed by Vert Design, the three-story Rideau Residences occupy a tight, 2,030-square-foot (190-square-meter) lot overlooking the Rideau River.
Photo: Cathy Rust Extra Large Image

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The contested Passive House certification of the Rideau Residences, a duplex infill building in Ottawa, Ontario, contributed to the eventual revocation of the certification authority of the Passive House Institute US by the Darmstadt, Germany-based Passivhaus Institut.
Photo: Cathy Rust Extra Large Image

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Although no longer Passive House-certified, the 3,300-square-foot (307-square-meter) Rideau Residences building is LEED Platinum-certified.
Photo: Cathy Rust Extra Large Image

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The Green Mountain Habitat for Humanity Passive House in Charlotte, Vermont, designed by Albert, Righter & Tittmann Architects, combines classic New England style with game-changing energy efficiency.
Photo: J.B. Clancy/ Albert, Righter & Tittmann Architects, Inc. Extra Large Image

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The Grundschule Riedberg, a Passivhaus-certified suburban elementary school in Frankfurt, Germany, was designed by 4a Architekten GmbH.
Photo: Kevin Matthews/ Artifice Images Extra Large Image

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Circulation space in the Grundschule Riedberg is daylit and spatially exciting. It is also designed to be relatively compact, allowing an extra bit of initial construction investment to be directed into high-efficiency features.
Photo: Kevin Matthews/ Artifice Images Extra Large Image

ArchWeek Image

Louvers and lighting in the classrooms are managed with defaults established by straightforward central controls, which building users can override at any time. Modest energy flows in the Passivhaus system support this permissive approach while maintaining extreme overall efficiency.
Photo: Kevin Matthews/ Artifice Images Extra Large Image

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The Passive House-certified Stanton House in Urbana, Illinois, was designed by Katrin Klingenberg.
Photo: Courtesy Katrin Klingenberg/ Darcy Bean Custom Construction


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