PHIUS+: Harmonizing Passive House and HERS

Back in the 1970s, energy costs were at the top of Americans’ minds. And building science thrived at places like the Small Homes Council at the University of Illinois at Urbana-Champaign, where the concept and term “superinsulation” was born. And in Canada, where the demonstration project called Saskatchewan House proved that airtight building envelopes, superinsulation, energy recovery ventilation and management of solar gain could be employed to build a practical, comfortable home—that didn’t need a furnace. Even in Regina, Saskatchewan.

Whether it was simple economics, bad policy, or a combination of both, the principles pioneered in North America foundered. In Europe, however, a Swede-- Professor Bo Adamson and a German—Dr. Wolfgang Feist, researched, refined and successfully demonstrated these principles in a systems approach. They developed a design approach and an stringent building performance energy standard called Passivhaus (Passive House).

Katrin Klingenberg, a German-born and trained architect—studied with Feist and set out to revive Passive House principles in North America. She built her own Passive House—in Urbana, Ill.—and built affordable housing (in partnership with the city of Urbana) projects to the standard.

In 2007 she and builder Mike Kernagis founded the Passive House Institute US (PHIUS), to train and certify building professionals to design and build using Passive House principles, and to certify their projects’ performance. Since then, awareness and implementation has grown dramatically. PHIUS has certified more than 200 Certified Passive House Consultants, who in turn have built nearly 30 certified Passive House projects. More than 60 other projects—residential and commercial—are in the certification review pipeline. The training schedule for 2012 is more ambitious than ever.

Still, work remains to transform Passive House in particular (and high-performance buildings in general) from a niche movement to a mainstream market force in the United States. For example, climate extremes in the United States are much more challenging than Central Europe, where Passivhaus has been widely adopted. In addition to adapting design and construction techniques, the standard itself may have to be adapted for some extremes (such adaptation has already occurred in Sweden, for example).

Another obstacle:  until now, a building team (and its client) could execute a superbly comfortable, ultra-efficient, high-performance building—but not gain the benefit of incentives linked to more established, mainstream ratings—like a HERS Index, which has become a de facto standard.

PHIUS and the broader Passive House community (including the chapter-based membership organization Passive House Alliance US) have for years been advocating for recognition of Passive House in energy codes and incentive schedules. That work continues, but until it is successful, it seems only reasonable to begin translating Passive House performance into terms that will allow builders to pursue incentives linked to already-established metrics—like HERS.

And so, PHIUS+ was born.

PHIUS signed a memo of understanding (MOU) with RESNET in February of 2011. The organizations have since collaborated to harmonize the RESNET HERS auditing process with Passive House principles. That has meant looking closely at procedures and the software used by RESNET auditors, to adapt the rating process to allow an accurate and meaningful HERS Index to be assigned to a Passive House project. In some instances, the process simply doesn’t recognize common Passive House principles. But by tailoring RESNET’s auditing process, Passive House homes can now be successfully tested with no software alteration required.

PHIUS+ also adds to a recognized quality control and assurance component to the Passive House verification process. Mid-construction on-site inspections and expanded verification upon completion make the verification RESNET compliant.

Just last month (Dec. 3-4), RESNET-certified raters from around the country got special training on Passive House design and construction principles. A combination of in-class and in-field training focused on concepts like finding and evaluating thermal bridging and inspecting super-insulated wall structures.  This pilot group will be assigned to rate the inaugural participants in the PHIUS+ program.

At PHIUS, we think this is an important step toward transforming Passive House from movement to mainstream. It leverages the awareness and acceptance of standards, processes, and labels that are better established in the United States than Passive House. We’re optimistic that it’s a major step toward making Passive House design and construction principles a mainstream market force.

More broadly, we hope that it serves as a model for harmonizing standards, rather than having them compete. 

Mike Knezovich works at the Passive House Institute US in Urbana, Illinois.