Foaming about Insulation

2010 February 5
by Otto
E.T. Foam Home

E.T. Foam Home

Using sprayed polyurethane foam for insulating is a no-brainer these days. It insulates much better than industry-standard fiberglass batts, both because it simply has higher insulating properties and also since the foam essentially eliminates convective heat loss (ie foam eliminates drafts). Closed-cell foams are also very rigid and contribute to the strength of the house.

Read anything on eco-friendly building, and you’ll find reference to closed-cell foam. It’s great stuff–at least in theory.

The local manufacturer of spray foam is Corbond. It has an R-value of about 6.2/inch. But I was a little suspicious that the guys who spray it in come dressed in hazmat suits. What’s up with that? Read on for some scary statistics.

All closed-cell spray foams are essentially foamy polyurethane, more or less the same stuff you use to protect wood furniture but with lots of bubbles in it. There are two mixtures that are mixed together as it is sprayed into place, the so-called A-side and B-side. The A-side is always isocyanate, and the B side is a proprietary blend of chemicals that includes the blowing agent.

The B side is mostly made of petrochemicals, which isn’t great from an environmental perspective, but I was really curious about the blowing agents. If you visit the websites of manufacturers like Corbond, they go to great lengths to highlight the fact that their blowing agents don’t deplete the ozone layer, but are curiously silent about the global warming potential (GWP) of the product.

I called Corbond and talked to a sales guy named Jeff. He sounded stumped by my questions about the blowing agent, ultimately saying that he thought no one really worried about the GWP of the blowing agent and that, in any case, the amount of energy you’ll save far outweighs any immediate climate damage the foam might have. That sounded valid. He also emphasized that about 90% of the blowing agent remains trapped in the hardened foam, so only about 10% offgasses. Again, a valid point, at least until the house burns down or is demolished.

When pushed, he said that the GWP of the gas is “probably about 4-6 times worse than carbon dioxide.”

Well, not really. I did some online research, and discovered that the blowing agent I was told Corbond uses, 245FA (trade name Honeywell Enovate 3000), has a GWP of about 950. 950! That means that about 2 pounds of the stuff is as environmentally damaging as a ton of carbon dioxide. And 245FA is the industry standard. Virtually everyone uses it.

It turns out that this is, in fact, progress. Spray foams used to use CFCs, and then HCFCs, the same stuff we used as refrigerants and that tore an enormous hole in the ozone layer. It was great stuff, from a technical perspective, but it was killing our atmosphere. We phased that out by the end of 2004 for residential foams. But while 245FA, which is now the industry standard, doesn’t kill the ozone layer, it is just as bad as the old stuff when it comes to GWP.

I searched around for foams that use other blowing agents. I found a company called Foam Supplies that make a blowing agent called Ecomate. Amazingly, it doesn’t damage the ozone layer, has zero GWP, no volatile organic compounds (VOCs), and apparently works great. I called the company and spoke with a guy named Scott. He told me that the company doesn’t sell the blowing agent for the home spray market, using it instead for the automotive, boating, and commercial construction insulation market. The owner of the company, David Keske, has no interest in selling to residential construction, he said. This is how Scott described David’s thoughts on the matter: “He said that when he’s dead his son can do whatever he wants to” with this family-owned business. But Scott doesn’t expect big changes anytime soon. He said something to the effect that David had been burned by non-payment by some home spray company about 20 years ago, and hasn’t forgotten the slight.

More research revealed a product called BioBased 1701s, a soy-based, water-blown closed-cell insulation. This sounded promising. It has an insulation value about 20% less than Corbond, but otherwise is a huge step in the right direction. (The “soy-based” thing is a bit misleading, as it still contains a lot of petroleum-based chemicals. But the main thing is that “water-blown” has no 245FA!)

Foam Installation

Foam Installation

But what about this claim that you save so much CO2 because the insulation is so great? Well, that certainly has an important element of truth in it. Here’s my back-of-the-envelope calculation:

I will use about 1450 cubic feet of foam in my home. It weighs 2lbs/cubic foot. If 10% of that is the blowing agent, that means I’ll have 290 pounds of 245FA. At a CO2E factor of 950, that’s the equivalent of 125 metric tons of CO2.

To put that number in perspective: a round-trip flight from Bozeman to London releases 2 tons of CO2/passenger. The average American has a carbon footprint of 20 tons/year (A German, 9.5; global average 3.8).

Now I was starting to wonder about just how much this stuff contributed to the national carbon footprint. I put in a call to the Spray Polyurethane Foam Alliance and spoke with the executive director. In 2008, he said, the market for 245FA-spray foam was about 380 million pounds in the USA alone. If 10% of that is the blowing agent, that’s 38 million pounds. Multiply that by the GWP of 950 and you get 36 billion pounds, or 18 million metric tons, or about .25% of the entire nation’s carbon footprint. More than the entire country of Estonia.

When I asked the SPFA director why they don’t use water-based foam, he sounded confused. Hadn’t really heard about it. Companies make claims. Wasn’t sure. The bottom line: Honeywell wants to make money on its patent!

So what did I do? Here I have to make a confession. The 245FA-foam people gave me a quote of $11,000 for the entire house. The water-blown guy quoted me $17,000. I simply didn’t have the budget for an extra $6,000. I went with the bad stuff.

6 Responses leave one →
  1. February 6, 2010


    You did your research! I am very impressed that you were able to calculate all of those figures and actually obtain some of the “secret” information that you did.

    I have to take you for your word on the calculations for the quantities of comparable Co2 inside the closed-cell products an credit you for being bold enough to point that out.

    One point that you made which is valid but disconcerting to me is the event of escape of the 245FA into the atmosphere. As you said, during a fire this would happen but the actual toxicity of many other building materials in the house will be far more harmful to the environment. Not to mention the harmful effects or borate, formaldehyde and other bonding agents and fire retardants in fiberglass and cellulose insulation. Closed-cell foam torn out during a renovation can and should be sent to a recycling plant, there are many available.

    I also noticed that you strictly focused on a closed-cell product, which I can understand because it brings the most environmental concern regarding the 245FA. You could have opted to go with and open-cell foam that relies on a steam reaction and air to create the bubbles inside the foam which act as the insulator. Most open-cell foam products do not rely on 245FA to increase the r-value. You mentioned that the product you decided to go with has a r-factor of 6.2/inch. You could have sought out a 1.0 Lb. open-cell foam offering an r-value of 4.5/inch and used that in all of your non-moisture related spaces. One example of a product is Demilec’s Agribalance which I have used hundreds of times in combination with a 2.0 Lb. closed-cell foam for the basement sill areas and areas that have moisture concerns and are hard or impossible to tackle with a vapor barrier.

    As far as the foam guy that uses it for furniture, automotive, etc. The process is not the same. Spray foam used in homes needs to rise and typically have a volume of 1.8-2.2 Lb./Cu.Ft. This is not the case with much denser types of rigid foam. The reason that 245FA is used by most foam companies that sell foam to the construction market is that it allows for proper expansion while maintaining a high r-value. If one was to use a mix of materials such as this guy uses it would get sprayed on at 1/32nd of an inch and barely expand, if at all. It would go on very sloppy and not fill gaps through expansion.

    My last note is regarding your quote, “The “soy-based” thing is a bit misleading, as it still contains a lot of petroleum-based chemicals.” I have to agree with you 100% that this is a misleading advertising scheme…however…I understand what it means to be qualified as a soy-based foam. As you said there are parts A and B and parts A are virtually the same across the board. In order for a foam product to be registered and accepted as a Soy-Based product it must contain 9+% soy/recycled/renewable materials. After you break it down it seems small but the fact is that spray foam insulation is the way of the future and will be used in 75% of all new construction in the next five years. Having 5% of the total materials being soy based, reused or renewable in a $100 billion industry is a step forward.

  2. Otto permalink*
    February 6, 2010

    Thanks for your long and thoughtful reply.

    A few comments back:

    1. Regarding 245FA closed-cell foam vs. water-based open-cell foam. I think the best solution is the closed-cell water-based foam. I’m no expert, but there are companies out there that claim to have a closed-cell foam that has all of the great R-value, rigidity, and crack-sealing power of the 245FA foam, except that it has essentially ZERO carbon footprint. Assuming that I’m not being misled by the product claims, I simply don’t understand why the entire industry doesn’t adopt it! (Except that I assume the industry is bought and paid for by Honeywell.)

    2. I may well be wrong about the automotive foam. Except that a guy I talked to at the company claimed that they had once been in the residential market, but the owner had a bad experience and chose to exit the market. Who knows.

    3. I don’t understand the “soy-based” vs non-soy-based thing well enough to really comment. I agree that 9% is better than nothing. But don’t forget that modern soy is essentially a by-product of the petroleum industry itself (akin to #2 Feed Corn). Most importantly, I think the blowing agent is the big problem.

    4. Recycling of closed-cell foam. You’re absolutely right. I painted perhaps a bit darker of a picture on the CO2E emissions of the 245FA, since much of the propellant will remain locked in the foam and then recycled at some point. Still, I remain baffled that the water-based closed-cell foams haven’t rendered the entire discussion obsolete.

    Thanks again,

  3. David Boggeman permalink
    February 8, 2010

    You omitted what I would consider the most important calculation. Carbon released from the foam compared with carbon from the difference between fiberglass insulation over the projected life of the house.

  4. Otto permalink*
    February 9, 2010

    David — Thanks for that comment. Here’s why I consider that calculation moot: from what I understand, water-blown foam has the same R-value as 245FA-blown foam. In fact, some sources tell me that water-blown foam has better “aged” R-values, because the 245FA both escapes the foam over time and also breaks the foam down. So if you use water-blown foam you don’t need to do add life-cycle carbon. If you’re comparing using a lesser insulator (fiberglass etc), then you’re absolutely right: You would need to add in the extra carbon cost of having worse insulation. With those enormous CO2E numbers of 245FA foam, though, my hunch is that you could use that house for many years before you match the carbon footprint of installing the foam.

  5. Randy George permalink
    November 9, 2010

    Great discussion… Did you ever look into airkrete? I just found out about this stuff and it seems to have most of the good attributes of traditional spray foam and none of the bad. Apparently it might even absorb CO2 (seems too good to be true). Randy

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  1. Comments posted on another blog regarding closed-cell spray foam, very informative! | Soy Based Spray Foam

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