Is Roxul or EPS more environmentally friendly overall?
Marc Sloot| Posted inGreen Products and Materialson
I certainly like that Roxul has high recycled content, but this PDF published by Roxul makes it look like EPS actually has a lower Lifetime GWP / sq. ft x R. Wouldn’t that make it a better choice in the long run?
http://www.roxul.com/files/RX-NA_EN/pdf/Brochures%20and%20Sell%20Sheets/Residential/DrainBoard.pdf
The document shows Roxul = 0.0455 and EPS = 0.036.
In addition they are comparing to a 1 pound EPS that only has R3.9 per inch.
If I am using Foam Control 2 pound Type IX the R value is listed at 4.35 per inch (75 degrees F.)
Would that be an even lower Lifetime GWP?
Thanks,
Marc
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Replies
The major lifecycle GWP of EPS is from the polystyrene production, not the pentane blowing agent, which may not be identical per board-foot for Type-I and Type-IX production.
Type-IX has 2x the amount of polymer and probably about 2x the embodied CO2 emissions for only about a 10% boost in performance
But I guarantee you it's more complicated than that. My gut says the true GWP for blowing Type -IX isn't quite twice that of Type-I EPS, but it sure isn't lower impact.
But it's still pretty low-impact stuff, from a global warming potential. If I had to guess Roxul is slightly lower impact than Type IX EPS but they're both at the low-carb end of the scale compared to foams with nastier blowing agents, or even fiberglass, but higher-carb than cellulose.
I agree with Dana: once you've moved from XPS or sprayfoam to EPS or mineral wool, you've gotten rid of the major impact, and you'd be better off spreading the word about the problems with XPS and sprayfoam than splitting hairs over which of the good ones is better.
Also consider the toxicity of the flame retardants in EPS (and XPS). I used to think that those were embedded in the foam and unlikely to come out and be a problem, but now that there is foam "sawdust" scattered around my building site, I'm not so sure--the fire retardant in that dust has a good start on participating in the ecosystem. The foam can be cut by scoring and breaking rather than sawing, but the chances of that happening on a construction site seem small.