Wednesday, June 9, 2010

What the Foam?

As shown in an earlier post, we planned to use closed cell spray polyurethane foam (SPF) for the wall sections in the renovated part of the home.  There are a variety of reasons for this – R-value per inch, air sealing properties, and moisture barrier properties.  The foam we had chosen looked to be about the best on the market in terms of IAQ, recycled content, bio content etc.

There were two main drawbacks of this approach in our minds –

1-   the embodied energy in the foam and blowing agent

2-   the issue of disassembly – meaning once you foam a bunch of elements together, they can’t be separated for re-use when the house is torn down.

Weighing the pros-and cons of this, and making some assumptions about the embodied energy/ embodied carbon – lead us to justify the foam……until last week.

Daniel Bergey and John Straube recently published their findings of a life cycle analysis of the global warming potential of the foam products versus the global warming savings from the energy that is avoided from insulating.  The results have been summarized and re-published here -

The short story is that if we extrapolate their data to the One Planet Reno project, it is likely to take 60-80 years of energy savings to overcome the global warming effects of the foam and blowing agent that we had planned to use.  Needless to say, that is not congruent with our goals of mitigating climate change.

More discussion on this topic and its implications to follow in later posts.   Some options include using water or CO2 blown foam, reducing the amount of foam so we get the air sealing benefits that we desire, etc.   For now, we encourage you to click the link and review the research. Needless to say the new design will respond to this unfortunate reality.

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