A new certification combining the Passive House standard with the Home Energy Rating System (HERS) Index might change the way Passive Houses are designed and built in the United States.
According to Katrin Klingenberg, cofounder and executive director of Passive House Institute U.S. (PHIUS), the new standard, called PHIUS+, will make Passive House buildings more compatible with other green rating systems, while adding better quality assurance to projects by requiring that raters qualified by the Residential Energy Services Network (RESNET) conduct blower-door tests and insulation inspections. She adds that PHIUS+ should also make Passive House constructions eligible for tax incentive programs. The new certification will be separate from the international Passivhaus standard, but will still have to meet the three performance metrics that for the base of the German-invented standard.
The development of PHIUS+ was apparently one of the three main factors that let to the schism between the international Passive House Institute (PHI) and PHIUS, which left things in the Passive House community a little uncertain. It’s too early to tell how the new certification will be accepted by designers and the green building marketplace, when the Home Energy Rating System (HERS) starts issuing PHIUS+ certificates, in January 2012, but supporters like Klingenberg hope the above mentioned benefits will convince people to welcome the change. But Passive House consultant Bronwyn Barry told Architectural Record that although “adding the HERS Index and alignment with RESNET was a great move on the part of PHIUS”, the American Passive House Institute had a lot more to gain by staying connected to the international Passive House community than by creating their own system with no brand recognition.
While Klingenberg regrets the parting of ways between PHI and PHIUS, she says the energy models produced by the Passive House Planning Package software program owned and distributed by the international body need to be “translated” for North America. She says that before the separation, any Passive House building modeled in the international software could be rated using HERS model, but the results were not relevant because of differing assumptions in the calculations. For example, a building modeled as net-zero-energy in the Passive House Planning Package might receive an unexpectedly high HERS Index due to these differing assumptions. This is exactly what PHIUS+ is trying to fix, by aligning the underlying assumptions.
Only time will tell if the development of PHIUS+ was a good move on the part of the Passive House Institute U.S., but I think Bronwyn Barry hit the nail on the head when he noted that “most practitioners of Passive House don’t care what the certificate itself is called. They are simply interested in building better buildings.”
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