What's the Greenest Insulation?

Recycled denim insulation being installed in a roof.

jacquie van wagner / Flicker / CC BY-NC-SA 2.0 

Sometimes I get it wrong in this gig, but rarely have I been so consistent as I have been in my coverage of Ultratouch Recycled Denim Insulation. I had to retract about half my previous post where I complained that shipping old jeans all over the country wasn't exactly green; Bonded Logic, the manufacturer, contacted me to say no, it is almost all post-industrial scrap from factories, diverting 300 tons of it from the landfill every month. Campaigns like those of Habitat for Humanity make up only a small portion of it. But I still thought it was over-rated, and preferred spray foams, particularly icynene, which I claimed was totally benign and had no volatile organic compounds.

Then I got into a fight with Kevin Royce of Eco Building Resource at the National Home Show in Toronto, and did I get schooled.

I started by complaining that sprays are better than batts, that they seal better.

"Right. You have guys in suits and goggles and respirators installing the spray foam. If it is so green, why do they have that?"

I said that that may be true with polyurethane sprays, but that Icynene had no VOCs and was perfectly safe.

Kevin said "Check again."

And sure enough, it does emit VOCs. Not much, they are all gone quickly:

In the dynamic chamber tests, several series of offgassing products were observed, all of which declined in concentration to 0.05 mg/m3 or less within 14 days, and to less than the detection limit of 0.003 mg/m3 within 30 days.

But strictly speaking by the book, they are not VOC free. Score 1 for Kevin. And while I was digging, I found out that it is a modified urethane made using petroleum products. Score 2 for Kevin.

Then I complained that their ads show little kids using ultra Touch as pillows, but the Material Safety Data Sheets say you should wear an OSHA approved air mask.

"Right. It's Borax. Your Grandmother probably washed your face with it."

I complain that it is the perfect nest for mice.

"Right. Why do you think it has borax in it? Mice hate the stuff."

I could go on, but it is too embarrassing. I slunk out of the Home Show and checked my mail.

In which Daniel Morrison notes that the EPA lists some problems with urethanes:

Spray polyurethane foam (SPF) insulation is a highly effective weatherization product that is playing an important role in national efforts to dramatically increase the energy efficiency of our homes, schools, and buildings. However, SPF foam contains diisocyanates, and dermal or inhalation exposure to these chemicals can cause significant health risks, such as asthma and lung damage, if specific workplace precautions are not followed during product application and clean-up. Risks also may apply to building occupants who may remain on-site during or re-enter shortly after application.

But the current EPA thinking is that "once the foam is cured, ventilated and cleaned up, and enclosed behind wallboard or roofing materials, residual off-gassing at unsafe levels is not very likely."

Morrison concludes that the final answer is far from unequivocal. But commenters thought otherwise and provided a lot of detail. Robert Riversong writes:

I agree that the outgassing poblem is largely overblown (except for those few who have become chemically-sensitized and have to spend the rest of their lives avoiding the world), but there are many legitimate arguments against the use of a petrochemical, high-embodied energy, non-renewable, non-recyclable, non-permeable, difficult to remove, problematic for renovation, and expensive insulating material.


There is still no question that spray foams do a better job of sealing and have a higher R-value per inch, and there are many different kinds, often made with soy oil or castor oil, open cell and closed. Some are better and greener than others. But if you care about building a healthy house, minimizing use of petrochemicals and maximizing your use of recycled materials, the recycled denim insulation clearly outperforms spray foams and even my beloved icynene. Mea Maxima Culpa.