Comments on: Calculating the Global Warming Impact of Insulation

By: Davin eberhardt

Davin eberhardt — Tue, 25 Feb 2020 16:52:42 +0000

I’ve read through the
I’ve read through the articles between you and Alex. Played around a little with spreadsheet but not sure all of its assumptions and if it would lead me to the answer I’m looking for..

I’m trying to get my head around the impact of insulating basement walls with 4” – of XPS versus GPS.

I know GPS would be the go-to. But it’s an hour drive one way to the supplier that can order it for me, and costs double the amount of XPS at a big box 5 mins from my house. Even more if I have them deliver.

Based on all your research, how much of a difference would there be in these two choices?

The extra carbon that went into making money for the price difference and pickup/deliver mileage..would GPS be worth it in climate zone 5?

By: Anonymous

Anonymous — Thu, 08 Dec 2016 16:22:35 +0000

In reply to Anonymous. R14 is but a reference point.
R14 is but a reference point. You're looking at what ~R30 using ccSPF in a 2x6 wall? The graph covers that.

By: Anonymous

Anonymous — Thu, 08 Dec 2016 16:17:18 +0000

In reply to Anonymous. Air leakage introduces
Air leakage introduces another variable that's basically out of the scope of this particular post. Of course if (that's a BIG IF) properly applied ccSPF does a great job for air sealing, but it's a Band-Aid for a poorly assembled enclosure.

By: Anonymous

Anonymous — Wed, 07 Dec 2016 18:56:36 +0000

@Allison, I agree that unless
@Allison, I agree that unless and until XPS manufacturers come clean on blowing agents, we should assume worst-case. Your XPS curves are based on HFC-134a, right? However, I disagree with blanket advice to avoid XPS. With the exception of the HP/clean electricity scenario, your graphs demonstrate that XPS has a net-positive GWP impact up to a point. In particular, if we assume non-foam insulation in the cavities with XPS exterior insulation (a very common configuration), incremental increases to both cavity and continuous R-values should remain well under the XPS inflection point for most projects. OTOH, when designing a home with clean grid power or on-site renewable energy, I agree that those who care about GWP should consider other options, or press XPS manufacturers to come clean on their blowing agents.

By: Anonymous

Anonymous — Wed, 07 Dec 2016 15:11:44 +0000

Allison, I think the blowing
Allison, I think the blowing agents that you are showing at least for the XPS and maybe for the Spray Poly are no longer in use by those manufacturers.

By: Anonymous

Anonymous — Wed, 07 Dec 2016 06:56:02 +0000

Author: Have you heard or
Author: Have you heard or read about Hempcrete? Sustainable Insulation Material that withstands fire, insects, etc. Walls, floors, ceilings and yes even wall assemblies. I would be interested in seeing "natural vs man-made" energy stats if you want to delve into something truly sustainable. If you need info on Hempcrete, I'll gladly share. Peace and Thank you for addressing the "blowing agents" true cost to the climate. Scotty

By: Anonymous

Anonymous — Wed, 07 Dec 2016 00:49:53 +0000

Thanks for the info. If
Thanks for the info. If people want to go “all out” they should look at Athena Impact Estimator. It will give you global warming potential, acidification potential, human health respiratory effects potential, ozone depletion potential, smog potential, and eutrophication potential. The Impact Estimator additionally reports fossil fuel consumption.
The software is free and is regionally customized and fairly easy to use.
You can find it here (http://www.athenasmi.org/our-software-data/impact-estimator/)

If you are a spreadsheet junkie try their Ecocalculator
( http://www.athenasmi.org/our-software-data/ecocalculator/ ) it is not as broad as the Impact estimator but gives you good data.

By: Anonymous

Anonymous — Tue, 06 Dec 2016 13:27:27 +0000

Very interesting. I'm curious
Very interesting. I'm curious, what about air leakage? Obviously closed cell does a pretty amazing job with that. I've become a big fan with existing homes. It's tough to do a good retrofit without it. My minimum leakage reduction in the last 2 years is 35%, the max is 75%. How much might that affect things? Could ccSPF come out ahead?

By: Anonymous

Anonymous — Tue, 06 Dec 2016 13:22:53 +0000

As the principal code
As the principal code official in NY State says in meetings, code it the lowest quality minimum. As architects we should never abide by it but use our training to give clients meaningful product. That includes going close to passive as it allows several aspects. Minimal heating and cooling (thus saving on maintenance and equipment wear and tearalone) with totally superior comfort, AND savings in average home in 30 year mortgage 250 000 to 500 000 dollars.

By: Anonymous

Anonymous — Tue, 06 Dec 2016 13:20:39 +0000

Count us in the “new and
Count us in the “new and improved group” using the new greener blowing agents whose line would fall between your cellulose and the CCPU fa245 line. But what is significantly misleading about your chart is that all lines start from the same point – R14. If you were to use a 2×6 wall with ccspf you would be looking at a whole wall R value that was much higher than what 2×6 with cellulose could offer. And if you only stopped with 2″ of ccspf to reach your R14 then you have huge open air cavities inside the wall which are not doing anyone any good.

So I am basically in agreement with what you are saying, but the presentation of the data presents a false equivalency that I hope would not be encountered in the real world.