The Passive House Institute U.S. (PHIUS) will no longer give its blessing to projects incorporating spray polyurethane foam insulation (SPF) that uses blowing agents with high contribution to global warming, according to executive director Katrin Klingenberg.
“It does not make any sense at all to use them if one of the major overarching goals of energy conservation in buildings is to counteract and decrease global warming and climate change,” Klingenberg says. “There really is no point to go through all the trouble of detailed Passive House design calculations if you use high-GWP [global warming potential] spray foam.”
In the past, Klingenberg said, projects have been permitted to use small amounts of SPF, but now that the U.S. group has started its own certification program, PHIUS+, even small amounts will no longer be allowed. For the time being, projects using low-GWP spray foam can still be certified as long as the “balancing requirements” that weigh material performance against carbon emissions are met.
However, PHIUS is planning to issue detailed guidance on the embodied energy of all petroleum-based insulation materials. “In the future I would like to add the embodied energy to those balances because of the significance in super-insulation,” Klingenberg says. The PHIUS+ certification will recommend (but not require) renewable insulation materials with low embodied energy except for “a specialty application where no other insulation material will perform.” For below-grade applications, Klingenberg prefers cellular glass but says high-density expanded polystyrene (EPS) is acceptable.
For projects that were already in the pre-certification process before the new PHIUS+ program was introduced in November 2011, the SPF rules will be optional. Final program requirements for PHIUS+ will be available on January 1, 2012, through PHIUS.
Global warming potential and insulation alternatives are explored at length in The BuildingGreen Guide to Insulation Products and Practices , which offers detailed guidance for specific applications.
Copyright 2011 by BuildingGreen Inc.