Two different approaches to achieving Passive House certification

I have had my eye on the passive house concept for the better part of a decade now. Essentially, builders are able to achieve unprecedented energy savings and occupant comfort using extremely tight building envelopes combined with high levels of insulation.

The always informative folks at Green Building Advisor have brought back some observations from the recent North American Passive House Network conference in Portland, Maine. In particular, Scott Gibson compared two different approaches to achieving passive house certification: one using the increasingly popular (in green building circles) foam insulation, and another that avoided foam insulation altogether.

What troubled Michler was “the legacy of toxicity” that foam insulation represented. He objects to its high embodied energy, the global warming potential of its blowing agents, and the extremely slow payback of using large amounts of it in a building. Spray polyurethane foam has more than 100 times the greenhouse gas potential as cellulose, he told a conference panel; expanded polystyrene has as much as 90 times the embodied energy as cellulose…

If Michler had the luxury of working on a guest house on his own property, and the time to feel his way through some of the building details, Vahid Mojarrab faced a completely different set of challenges: How to build to the Passivhaus standard with a labor pool familiar only with conventional techniques, and do so quickly and efficiently enough to stay competitive on price…

Mojarrab’s plan was to stick as closely as possible to familiar building practices so crews wouldn’t have to learn an entirely new way of construction. He had two other advantages: an investor named Bob Schneck who was wanted to collaborate with Mojarrab to advance Passivhaus building in the region, and energy modeler and “Passivhaus optimizer” Graham Irwin of Essential Habitat in California.

Well worth a read…

Source: Green Building Advisor

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