XPS & global warming: Updates?
I keep reading that different, less harmful blowing agents than HFC-134a were supposed to come online for XPS foam. Some of these articles date back a few years, and make it sound like the change was imminent. Did any of this ever come to pass? Or are we still dealing with the status quo? The latest article of this kind was on GBA a few months ago. https://www.greenbuildingadvisor.com/blogs/dept/green-building-news/new-blowing-agent-lower-environmental-impact
Owens Corning Foamular is the most commonly used product in my area. This page (http://insulation.owenscorning.ca/architects/products/c-200.aspx) claims that Foamular has “70% lower global warming potential” than their previous XPS. Has the blowing agent changed from HFC-134a with it’s GWP of 1,430? Is the new impact GWP of 1430 x 30% = GWP of 429? Or is this more industry BS?
Here’s my real question: For the time being, should I continue to assume that the XPS at my local building supply store has an absolutely horrendous GWP, and continue to use other materials (EPS, polyiso, confortboard, etc) when practical, if I really care about global warming?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Peter,
It might be time for GBA to write an update on this issue. As far as I know, the XPS that is sold in the U.S. is still manufactured with blowing agents with a very high global warming potential. (It's hard to evaluate the Owens Corning claim without knowing the actual blowing agents being discussed. The company may be comparing their 2009 blowing agent with their 1979 blowing agent.)
European XPS -- the good stuff which is more environmentally benign -- has an R-value of R-4 per inch. So as along as Owens Corning is advertising that their XPS is rated at R-5 per inch, I would assume that it's the bad stuff.
Needless to say, though, GBA probably needs to do some digging and report back to our readers.
In response to some other discussion here I found out what I could about the Owens Corning claim and it seemed that they were using a different mix that indeed is ~430 GWP. That's an improvement, yes, but it's still two orders of magnitude worse than EPS, so I would say that the answer to your "real question" is simply yes.