Avoiding the Global Warming Impact of Insulation

Cellulose is so much more green
by adkjac upstateny

Cellulose is a greener insulation product acording to your info by an order of magnitude.

Why do building scientists push foam????

I like foam too... but am leaning toward soy based water blown.... and any recycled foam I can get which there is plenty available from commercial reroofing disposal men.

Thanks for tackling this
by John Semmelhack

Alex,

Thanks for tackling this subject.

Can you share some of the manufacturers or brands of closed cell foam that use water blowing agents? I haven't been able to find any.

The reality is soy based foams are not necessarily better
by Kyle

As Alex points out the permisity of some of these high GWP foams is very attractive from a building science perspective in some applications.

It is unclear if soy based foams (ie foams that use soy oil as a feedstock in place of petroleum) have much positive impact at all, possibly none. I am setting aside the question of blowing agents.

Current research has shown that using food based agricultural products as fuel feedstock has caused major land use changes that has increased global warming. The EPAs new rules for classification take into consideration both the lifecycle production related global warming impacts of biofuel production and indirect inducement of land use changes that significantly add to global warming (this is caused by pulling fallow land back into production and deforestation to put new land into agricultural production in developing countries like Brazil). This type of holistic approach is appropriate for food based feedstocks used for insulation as well. Both a standard lifecycle approach and indirect impacts of land use need to be considered to fully understand the global warming impact of food based feedstock in insulation.

Plus most of the soy based products I am aware of only use soy as part of their feedstock and it does not displace oil as the principal feedstock. But again displacement is not necessarily a positive thing.

see article in annual reviews of Ecology, Evolution, and Systematics
http://arjournals.annualreviews.org/doi/abs/10.1146/annurev-ecolsys-1022...

GWP of Cellulose?
by Simon Hare

Interesting post, although it would be even more insightful to compare GWP of foams with other insulation materials such as cellulose. A clear disadvantage of the latter versus foam is that wall cavities grow substantially in thickness, which becomes a significant challenge in superinsulated retrofits and new construction in dense urban areas.

Has EBN conducted similar GWP analysis of cellulose? If yes, please share the results.

Thanks.

GWP of cellulose
by Alex Wilson

The GWP of cellulose results from the embodied energy of producing and transporting cellulose. That information is shown in the charts. In the first chart, the cellulose line hugs the bottom of the graph; in the second I've changed the scale so that the non-HFC insulation materials can be compared. (To see these graphs you have to click on the thumbnail images at the bottom, or click on the house photo then click the forward arrow to see the additional images.)

This analysis does not directly account for the GWP impacts of thicker walls, per se; I'm not sure how you would do that.

an alternative to insulated walls
by mike

would be building without insulation.

it can be done, and elegantly at that...
http://bruteforcecollaborative.wordpress.com/2010/02/12/das-kybernetisch...

Cemintitious spray foam
by Mark Weir

Thanks you for the analysis Alex. I am curious as to your thoughts on cementitious spray foam such as air krete, composed of inert materials. Reading the promotional material, seems like a reasonable alternative, although not the highest performance at R 3.9 per inch and limited availability.

On cementitions foams
by Alex Wilson

I have long liked Air Krete, though there are a couple problems: first, if it isn't installed just right there can be significant problems; and second, the cured foam is fairly friable, meaning it can disintegrate fairly easily and may not be appropriate for applications that are exposed to a lot of vibration (such as a building along a busy roadway). Last I checked, the manufacturer had (to their credit) resisted the temptation to add an organic polymer to solve the friability problem, hoping to keep it 100% inorganic and fire resistant.

If I were in the product development field today, I think I'd be focusing on "foamed ceramic" insulation materials. I believe there is huge potential here--essentially producing a "beadboard" insulation made of fused expanded ceramic beads. Such a material a) would be totally firesafe (zero flame-spread and zero smoke-developed) without the use of flame retardants; b) would be highly durable; c) would insulate reasonably well (it would be great if such a material could achieve R-4 per inch); d) would exhibit reasonable permeability to allow wall cavities to dry; e) would be moisture-resistant and not prone to decay; and f) would have enough compressive strength to work in below-grade and even sub-slab applications. I saw prototype materials along these lines (expanded inorganic beads) 15 years ago and suspect that someone is working on a product like this. I can't wait.

Is there a magic zero GWP polyiso blowing agent?
by Skylar Swinford

Alex,

I just stumbled upon Atlas Roofing's website where they are claiming that their "Energy Shield" polyiso foam board offers zero GWP. Below is a quote taken from the Energy Shield product page:

"Energy Shield offers several “green” qualities, including zero Ozone Delpetion Potential (ODP) and zero Global Warming Poteential (GWP) due to Atlas Blowing Agent Technology.
(Note to Atlas, typos do not generally add credibility to bold marketing claims)

Check out the claim for yourself: http://www.atlasroofing.com/tabbed.php?section_url=15

According to your article the blowing agent used for polyiso is pentane which has GWP of 7. Perhaps Energy Shield has a magic "proprietary" blowing agent, but it reeks of greenwash to me. I will drop them an email and see what's up.

Thanks for another exceptional article.

On the GWP of pentane
by Alex Wilson

I believe that because the GWP of pentane and related hydrocarbons is so close to zero (7 really is pretty low), manufacturers have always considered it insignificant. Water-blown SPF, for example, actually has CO2 as the blowing agent (CO2 derived from H2O--I think that's how the chemistry works), so that GWP would be 1 for that blowing agent. From the numbers we came up with on payback, as long as the GWP of the blowing agent is less than 10 or 20, I don't think there's much to worry about. At that level, the GWP of the embodied energy is on the same order of magnitude--and energy savings quickly pays back this environmental impact.

Foam Glass
by John Semmelhack

Alex,

The "foamed ceramic" product you describe is already available (in Europe). It's foam glass. One of the more popular versions of foam glass is foam glass gravel for below grade applications. It has just about all the properties you describe: firesafe, durable, low thermal-conductivity, moisture resistant, and good compressive strength. And, for comparable R-values, it's about equal on cost with XPS insulation. I bet it will be available in the U.S. in the next 24 months.

For an example, check out http://www.millcell.com/en/millcell

FoamGlas
by Alex Wilson

John,
Pittsburgh-Corning has made Foamglas (trademarked name) for years, and I am a fan of the product. It's marketed in the U.S. for industrial applications (insulating steam pipes and such), but not so much for building insulation, though the company has promoted it to some extend as a roof insulation for use with green roofs. I'd love to see either P-C's or someone else's foamed-glass product marketed actively here. The "foamed ceramic) product I envision is a little different: lighter weight, more the look and feel of EPS (though not as spongy), and lower-cost. Pipe dream? Perhaps, but one can hope!

millcell insulation
by adkjac upstateny

U - value: 0,15 for 16cm is that equal to R-1 per inch? Not so good is it?

adkjac's math
by mike

U=0.15 is R-38.
16cm = 6.3"
R-38/6.3" = R-6/inch, which isn't too shabby.

Millcell R-value
by John Semmelhack

Adkjac,

I'm not sure where you got the U-value of 0.15 for 16cm. It's not correct. The Millcell website claims a thermal conductivity of 0.0753W/mK for the product once it's compressed...that's R-1.9/inch.

http://www.millcell.com/en/specifications/properties/

Recycled Cotton Insulation
by Steve K

Alex,

This is a great article. Thank you.
I wish you had included UltraTouch Cotton Insulation as well. Did you include that in your research?

UltraTouch cotton
by Alex Wilson

Steve,
I did not include cotton, because I didn't have good embodied energy data on it. Having recently toured the UltraTouch factory near Phoenix, though, I would guess that the embodied energy (and thus lifetime GWP) would be somewhere between that of cellulose and fiberglass: higher than cellulose but lower than FG. That's just a guess, though. There certainly is no halocarbon blowing agent. -Alex

Millicell Gamma Radiation
by dpk

On its web page, Millicell lists absorption of radiation among its properties. In terms of undesirable stuff like gamma rays, I gather this is indeed a good thing, and seems partly function of mass. I'm not going to start seeking out products based on this feature yet, though. Depleted uranium is excellent at blocking gamma radiation , for example, but might face marketing challenges....

LCA
by Mac Sheldon

The proper method of comparison of insulating materials is the Life Cycle Assessment for each insulation type, brand and installation method. Before the LCA can be done the Product Category Rules need to be agreed on and an inventory of components built. This work is in progress and until it's done, all comparison in forums like this, in the popular press and in marketing literature is pure opinion and conjecture.

Since we're offering opinions, mine is that spray foam is the most effective insulation on the planet because even an average SPF job will be well air sealed and the foam will perform for generations over a wide temperature range without settling or delaminating. SPF does not rely on caulking or tape to perfect the air seal, instead it is essentially glue that we foam up. If you've ever been to a jobsite where SPF is being sprayed you'll understand how it adheres.

There are better uses for recycled newspapers. There are better uses for recycled cotton. All air permeable insulation leaks energy by leaking air, and moisture-laden air traveling through or within an assembly leads to condensation which is the leading cause of building failures. It makes no sense to use air permeable insulation in our buildings if we're really serious about reducing energy demand.

There will soon be zero-GWP blowing agents available for medium and high density foam, but quite honestly, they will be incidental in the total scheme of things. If we reduce the energy demand of our buildings, we'll reduce the massive use of fossil fuels required to provide our requisite heating and cooling, and the offset carbon emissions will go a long way to justifying the very small amount of blowing agent that's actually present in medium density SPF (closed-cell). For the purists in our midst, the argument should be to eliminate all refrigerated cooling systems if we're dead set on reducing GWP gasses. After all, we had no AC in our buildings 60 years ago and we got along pretty well. OK....we want our comfort, so let's build the most efficient buildings possible, and that's most effectively and predictably done using spray foam insulation and air sealing.

Low Density foam like Demilec's Sealection 500 and Sealection Agribalance are so-called "water-blown" foams and have no GWP. Agribalance uses some Castor Oil based polyol which is not in our food chain, and has a very high R-Value for a low density foam of 4.45 per inch. Combined with its ability to air seal (air impermeable in accordance ASTM E-283 and ASTM E-2178) and insulate even behind pipes, wires, irregular spaces, tiny cracks, gaps and voids in the framing, this is perhaps the most intelligent choice available to the building community.

Just a note to the Author, Icynene is the name of a Canadian spray foam manufacturer, not a type of SPF. The proper terms for SPF and some of their synonyms are:
Low Density Spray Polyurethane Foam (Proper)
Open Cell Foam
Half-Pound Foam
Water Blown Foam
Semi Rigid Foam

Medium Density Spray Polyurethane Foam (Proper)
Closed-Cell Foam
Two-Pound Foam
Rigid Foam

High Density Spray Polyurethane Foam (Proper)
Roofing Foam
Closed-Cell Foam
2.5 - 3 Pound Foam
Rigid Foam

I live on a farm and have sheep eating the grass in my pasture. The lowest embodied energy that I can think of would be to shear the sheep with manual clippers (ouch!) and stuff the wool in the walls, but would that be the wisest choice based on wool's high air permeability rate? We'll get the LCA work done in a year or two and thereafter we'll more accurately be able to compare insulations, and until then I stand by my opinion that SPF makes more sense than any other commercially available insulation. By the way, think about who builds our homes.....young men in a hurry, right? Do they always get air permeable insulation perfectly aligned on all 6 sides? With spray foam it doesn't matter, the foam will flow to the nooks and crannies and the air seal will be far superior to any other system.

Lastly, please pay attention to flame retardants used in various insulation types. SPF does not use penta-brominated diphenyl ether (PBDE) Ask the EPS manufacturers about theirs.

Bad SPF Assumptions
by Andy Ault, CLC

Mac, I'm also a fan of SPF in it's various forms ... for the right SITUATION and with the right INSTALLATION. However, you make some big assumptions about SPF and in particular it's ability to be a cure-all when installed by "young men in a hurry."

Here's a link to a real-world field study of foam and it's problems with air-sealing based on faulty installation (based on fact not opinion): http://tinyurl.com/2765qph

Foam, like any product, is only as good as it's installers and, as they found in the article, can be more difficult than other options if it has to be corrected retroactively. Be cautious about declaring any single product the ultimate answer across the board.

Effects of Global Warming
by Jekin

I am very pleased to see that Cellulose Insulation appears to be the best choice for the most cost effective and environmentally friendly type of insulation in your charts. I have been using Wall Spray Cellulose Insulation in our walls for last 25 years. I selected it for its recycled qualities along with the ability to build custom sized batts in every wall. I know the "installed" R value is superior to other batt insulations. Along with our air sealant work, air tight drywall approach and Cellulose in the walls, we are building a durable high efficient house that will last for years to come.
http://www.globalwarming360.net/

Response to Andy Ault
by Martin Holladay, GBA Advisor

Andy Ault,
Great link -- thanks for sharing it. It's an eye-opener. (However, it's not a field study; just a blog entry.)

This got me a little angry
by Mark Bartosik

So over at www.buildingscience.com XPS is recommended for various applications.
Late last year I fitted exterior XPS to a few walls of my home. My aim was to be environmentally friendly. If the GWP payback is as bad as it appears by this article I feel defrauded (by Owens Corning).

In a retrofit of my home last year I used fiber faced polyiso, foil faced polyiso, and XPS, each in different places carefully considering the best material for the job. The XPS appeared best for the job in some cases.

So I did a little Googling of XPS and HFC-134a here is the top link:

http://www.arap.org/docs/xps_insulation.pdf

This report implies that using HFC-134a instead of C02 is overall a better energy payback (even after it says that HFC-134a has GWP of x1300 that of C02).

Indeed I recall researching this myself before I decided to use XPS.

So we have (at least) two reports:
http://www.buildinggreen.com/auth/article.cfm/2010/6/1/Avoiding-the-Glob... (the link this article was based on)
and
http://www.arap.org/docs/xps_insulation.pdf (an industry report -- by an employee of Dow Chemical)

So what is one to believe?
Could the report by an employee of Dow Chemical (makers of Blue Board XPS) could be biased or defective?

So I guess that at some point I will have to sit down and do the calculations myself, or at least try to validate both sets of opposing calculations and look for the descrepancy.

Of course finding out the exact blowing agent used, and the amount of blowing agent may not be easy.

Payback isn't the best metric.
by Allison A. Bailes III, PhD

Alex, this is interesting information, but payback isn't the most relevant metric to use. Since the blowing agents are released slowly while at the same time the building is reducing the output of other GHGs, it's the net GHG flow that matters. How much GWP do they produce each year, and how much do they offset? Did you look at that?

This is analogous to the irrelevance of payback when borrowing money for an energy efficient home. If the buyer isn't plunking down all the money at once, cash flow is what matters, not payback. Same thing here. And with the urgency that James Hansen ascribes to climate change, I think we should be more concerned with the immediate effects, not what happens over a lifetime of 50 to 500 years.

That said, I personally think peak oil is a more immediate problem, and we need to do whatever we can to reduce our energy consumption. And I mean reduce, not just become more efficient (http://hub.am/b8ocnN).

On "payback"
by Alex Wilson

Allison,
I agree that payback usually isn't a good metric when evaluating energy improvements--it might not be the best way to explain what I was trying to do in addressing global warming impacts of insulation either, though I think the issues are somewhat different. What I was trying to do was present how many years of energy savings will be required for a given amount of insulation to compensate for (or break even on) the greenhouse gas emissions of the insulation itself. It's a complicated issue, and I'm looking for other ways to present this information.

Ah, but it is the same...
by Allison A. Bailes III, PhD

Alex,
I think it really is the same issue - lifetime payback vs. short term net flow. I think I agree with Mac Sheldon here, that your results (and I must admit I haven't seen the full report) are speculative because you don't have enough data and you're using the wrong metric. (I don't, however, agree with Sheldon about SPF being a panacea.)

You give payback periods of 36, 46, 65, and 110 years for XPS, but what really matters is how much GWP does it produce in the first year compared to the GWP it offsets, then how much in the second year, the third year... To get those results, you have to know the offgassing profiles for the various products. It's easy to calculate the amount of GWP that's offset by the energy savings, but without having those offgassing data, you can say there MIGHT be a problem here. Or maybe there's not.

If a builder uses XPS or closed cell SPF and the energy savings that result from that choice have a net result of lowering GWP, it's a good choice. Without those data, however, the best we can say is that we don't know. When you say "Bottom Line – Avoid XPS and SPF," I believe you've gone too far. You're basing that conclusion on the assumptions you've made and the wrong choice of a metric.

Ah, but it is not the same...
by Martin Holladay, GBA Advisor

Allison,
Actually, Allison, it isn't always the same.

I'll take an extreme example to illustrate my point. Imagine an insulation that releases 100% of its blowing agent during its first year of service. Let's imagine that the GWP of the released blowing agent is twice as much as the reduction in GWP achieved by the insulation during its first year of service.
So the net GWP during the first year isn't any good, because during the first year you do more harm than good.

However, if the building lasts 50 years, and there is no further release of any blowing agent, then all of the energy savings that accrue over the next 49 years are a net benefit. So the balance during Year 2 (and Year 3, and Year 4, and Year 5...) is entirely different from the balance during Year 1.

You're right, of course...
by Allison A. Bailes III, PhD

Martin, you're absolutely right. The rate of offgassing usually does vary, with a lot of it happening in the early stages, so each year doesn't stand alone. As I said, I haven't seen the full report, but based on my read of what Alex said above, it looks like they assumed that half of the blowing agent is released over a period of 50 to 500 years. What number they chose for the release period, he doesn't say here. Whether or not they assumed uniform releases spread evenly over the entire period, I don't know either.

It appears, though, that Alex is saying to avoid XPS and SPF simply because of the long payback periods. What I'm saying is that that recommendation is not warranted because of the assumptions and lack of data about offgassing. Perhaps the full report contains crucial information that would change my mind, but if so, why isn't that info in this article?

In the meantime, I'm not going to stop recommending XPS and SPF.

Here's the skinny...
by Allison A. Bailes III, PhD

This report needs to be retracted. If not retracted, it should have a disclaimer at the top warning readers that it is just an exercise in simulation with no power to yield conclusions. It's not science, although it looks like it is. The conclusions are not defensible. Here's my analysis:

http://hub.am/an7fDi

Published Paper on blowing agents in SPF and XPS
by Kathy Garneau

I would like to contribute this link to a scientific paper written by Dr. Danny Harvey from the University of Toronto. I think Alex's report reaches similar conclusions and presents the material in a much more approachable manner. Note: Dr. Harvey's paper was published in "Buildings and Environment"

Net Climatic Impact of Solid Foam Insulation Produced with Halocarbon and non-Halocarbon Blowing Agents. 2007. Buildings and Environment 42(8): 2860-2879.

For a free version of the paper go to this link:

faculty.geog.utoronto.ca/Harvey/Harvey/papers/Harvey%20%282007c,%20BAE,%20Climatic%20Impact%20of%20Insulation%29.pdf

note: you need to add :http:// to the front of the link

Just read Dr Harvey's paper (in link 1 post above)
by Mark Bartosik

Dr Harvey's paper is very detailed and credible and worth a read, at least the abstract and final page or two if you are short on time.

A couple of sentences that I think gives a breif flavor:

"The small additional savings in heating energy emissions using halocarbon blowing agents is swamped by the larger impact of leakage of the blowing agent. Thus, non-halocarbon blowing
agents are again better from a climate point of view."

The paper is vastly more detailed.

This directly contradicts an industry (and likely biased) report:
http://www.arap.org/docs/xps_insulation.pdf

If pentane is used rather than HFC-134a there would be a huge improvement.

So while the report in this blog may not be as detailed as Dr Harvey's report the conclusions appear to me (for what I think are typical use cases for XPS) to be similar.