When we first broke the news of the split between Passivhaus Institute (PHI) and Passive House US (PHIUS), it was a murky proposition to project what the results would be. That answer has become much clearer in the past months after a series of proposed changes and intense debate within the community. The conversation heated up in the last week as those aligned with PHI asked PHIUS to choose a different name for their certification system from Passive House, and Katrin Klingenberg, head of the American group, got personal in her response. The question on everyone’s mind is: “how much damage does this cause the movement?”

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As you are probably aware, Passive House is a rigorous high-efficiency building standard first developed in the US in the 70s and 80s then perfected in Germany. It has come back across the Atlantic as a very specific energy standard with PHIUS leading the charge. The developer of Passive House, Dr. Wolfgang Feist severed the European relationship with the US, which resulted in a cleaved Passive House community.

PHIUS, under the direction of long-term director Katrin Klingenberg, recently unveiled a few tweaks to the standard, which resulted in a heated debate as to what Passive House really signifies. The changes have raised eyebrows – they included a retracted ban on some foams, and now a change in the basic base energy usage for some climates from the 15 kWh per square meter per year protocol. The argument is that the 7 climate zones in the US are much different from anything in central Europe, and the standard should be relaxed a little for cold places, and perhaps tightened for more mild zones.

The proposed change has stirred the passion of the Passive House consultants aligned with PHI, who have introduced a petition asking for PHIUS to renege on their use of the term Passive House, as they feel the change in metrics while using the same name will cause market confusion.  The turf war salvo is the latest move after PHIUS sent cease and desist letters to PHI representatives who were issuing the title of Certified Passive House Consultant and for allegedly using unauthorized email lists. The result is a tangle of personalities and metrics that run counter to the original spirit of a simple but rigorous energy-based building standard.

Perhaps the real confusion hinges upon the fact that the two groups are going after each other by playing so much inside baseball in public forums rather focusing on an anemic housing market that desperately needs the standard(s) implemented. Lloyd Alter from Treehugger puts a Plague on Both Their Passive Houses, and the very public conversation is spilling over in the comments on Green Building Advisor, with Katrin Klingenberg oddly calling out dissenters for their “little or no practical experience”, which simply added heat to a burning bridge.

A public squabble among a handful of participants can potentially hamper the implementation of Passive House, which has put many more folks on edge. PHIUS has historic precedence for changing the metric somewhat, as Europe has a host of Passive House certifying groups which have done the same. PHI has also been keeping a low profile and is gracefully allowing PHIUS to use their core energy modeling software. In the end the debate may be healthy if the result is a greater awareness of the intense vetting of Passive House and the passion and discipline all consultants put into making it a reality – or at worst the debate could completely turn the public off to the building standard.