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PHIUS and Passive Building in the United States

Q: There seems to be confusion around PHIUS in the United States and PHI in Germany. How are the organizations different?

A: To start, it’s important to understand that PHIUS and Passivhaus Institute (PHI) are, and always have been, two separate organizations. PHIUS, based in the United States, is a non-profit 501(c)3 founded in 2007 by Katrin Klingenberg and Mike Kernagis. PHI is a for-profit founded earlier in Darmstadt, Germany. They are two completely distinct organizations.

Q: PHIUS and PHI had a working relationship, but they no longer work together. What happened?

A: Some history is required to explain that.

The concepts of superinsulation, airtight envelopes, energy recovery ventilation, high performance windows, and managing solar gain originated in the United States and Canada decades ago, a reaction to the OPEC oil embargo. In fact, American Nobelist Dr. William Shurcliff wrote in the 1980s about passive houses.

Interest in conservation waned in the United States for many years. During that time, the Europeans refined the application of these principles and spawned demand for high-performance products. Dr. Wolfgang Feist, a German physicist, and Dr. Bo Adamson, a Swedish scientist, led the effort to refine the principles and develop the design techniques and the Passivhaus performance metric. The first Passivhaus was built in Darmstadt, Germany. Feist went on to found the Passivhaus Institut (PHI), which is headquartered in Darmstadt.

PHIUS co-founder Katrin Klingenberg studied architecture in her native Germany. She discovered Passivhaus and, following Feist’s lead, endeavored to re-introduce the now-refined passive house principles to the United States in 2002 by building her own passive house residence in Urbana, Illinois.

Since then interest has continued to grow in North America. Over that period, PHIUS’ Annual North American Passive House Conference has grown exponentially, drawing presenters, exhibitors, and attendees from around the world. It is the largest and most technically-focused such event in North America. 

PHIUS worked collaboratively with PHI for several years and became a distributor of the PHI’s Passive House Planning Package (PHPP) Excel spreadsheet, the original passive house design software. PHIUS developed an Imperial system (inch-pound) version of that software, which greatly increased adoption in the United States. PHIUS also created a North American focused training program and created the Certified Passive House Consultant (CPHC®) credential.

Over time, PHIUS and PHIUS-trained professionals learned that in North America’s climate extremes, passive building concepts and standards require adaptation if they are to be practical, cost effective, and adopted widely enough to make a substantial difference. PHIUS recognized the need to partner with major energy leaders such as the US Department of Energy (DOE), US Army Corps of Engineers, RESNET, Building Science Corporation, and Fraunhofer IBP in order to grow passive building principles from a boutique concept to mainstream adoption. This approach put PHIUS at odds with Germany’s PHI. PHI holds that a single metric should apply in all climate zones worldwide. PHI also objected to collaboration with the government and organizations such as RESNET.

Both organizations continue to promote passive building principles. But there are substantial differences in their approaches.

  • PHIUS collaborated with Building Science Corporation to develop cost-effective climate specific metrics. The three-year effort was conducted under a grant from the DOE’s Building America Program, and yielded a formula that produces the "sweet spot" where ambitious carbon and energy reduction targets overlap cost effectiveness. PHIUS implemented the new PHIUS+ 2015 Passive Building Standard – North America in March of 2015. That standard was updated in 2018, and PHIUS will periodically update it to reflect market, materials, and climate changes.
  • PHIUS will continue to partner with other organizations and government agencies wherever partnership can accelerate adoption of passive building principles.
  • Working with Fraunhofer IBP and Owens Corning, PHIUS helped to develop WUFI® Passive, the next generation energy modeling tool that combines hygrothermal analysis capabilities with passive building energy modeling. It also provides a critical capability dynamic modeling functionality.

Q: So, what about certification of both professionals and projects?

A: PHIUS is the leading trainer and certifier of both professionals and projects in North America.

PHIUS certifications of consultants and projects are not recognized or listed on the PHI database, and PHIUS does not recognize PHI projects in the United States and Canada. Professionals can earn both credentials, however through separate paths. There are also a number of PHIUS-certified buildings that have also been subsequently recognized by the PHI. Today, PHIUS offers the following certifications:

  • CPHC® (Certified Passive House Consultant): A design and construction professional who takes the CPHC training and passes the exam earns certification as a CPHC. A CPHC is a credential established and trademarked by PHIUS. PHIUS-trained CPHCs have the ability to design and energy-model new construction and retrofit scenarios across the range of North American climate zones.
  • PHIUS Certified Builder: In 2012, PHIUS launched the PHIUS Certified Builder training program. Over four days, students learn passive building principles and techniques; they learn to “speak passive house” with CPHCs. They also learn the critical points of construction details and the differences in managing the process. Students who pass the qualifying exam earn PHIUS Certified Builder status.
  • PHIUS+ Rater: Energy raters who are certified and in good standing with RESNET can take the PHIUS+ Rater training. It equips them to evaluate passive building projects by harmonizing their rating process with the passive building evaluation process. It also includes on-site checks and performance testing.
  • PHIUS+ Verifier: This 2-1/2-day training prepares third-party Quality Assurance and onsite verification professionals to understand the application of passive building and verification principles for multifamily and commercial projects pursuing PHIUS+ Certification. Successfully completing the course and exam qualifies the trainee as a PHIUS+ Verifier.
  • PHIUS+ Project Certification: Building certification is a critical point of divergence between PHIUS and PHI. While both certification programs focus on similar energy metrics and physics principles, PHIUS saw a vital need in the US market for third-party quality assurance. This is because passive buildings present their own unique challenges and risks to building professionals, and stringent QA protocols go a long way toward removing that risk as a barrier. In short, when someone goes to the trouble of building to passive standards, with PHIUS+ they get the maximum value certification and the greatest chance of earning energy-focused financial incentives.

Q: Are there any regional passive building organizations in the US?

A: To foster a passive building community and support network, PHIUS launched PHAUS (Passive House Alliance US) in 2011. The national membership-based organization consists of 18 local chapters from coast to coast and is the largest such organization in the United States. PHAUS provides information and supports the community through webinars, local meetings and events, and provides financial benefits to members including discounted rates on PHIUS-provided trainings, certification fees, and registration to the Annual North American Passive House Conference.

We believe that these regional groups are critical, especially in the United States, where each region faces unique climate, market, and code challenges. In addition to the collective learning that can be shared, these local groups are key proponents of passive building and advocates for code and other regulatory changes. Some regional groups have formed (or splintered) and have chosen not to join or affiliate with PHAUS. But we are all pulling in the same direction. Most of the individuals in these regional groups received training and/or certification from PHIUS, and many members of the non-affiliated groups maintain individual memberships in PHAUS. 

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