Spray foam, once thought to be a green option for insulating green buildings and homes, is on the hot seat right now. Treehugger released a five-parter series denouncing it last month, and advised us to give spray polyurethane foam a second thought.
All suited up, a worker installs spray foam insulation.
The ironic thing is that for many years spray foam is a popular building insulation material–it has good R-value, it’s affordable, widely-available, and best of all, happily LEED-compliant.
But according to Treehugger, there are some very compelling reasons for avoiding spray foam from now on.
1. Spray foam’s chemical components are toxic, and, worse, can even accumulate in the body faster than they can be flushed out. The very fact that builders working with spray foam have to wear masks and gloves for protection from both fumes and dust is testament to its toxicity.
2. Spray foam can offgas. Installing spray foam requires mixing two liquid components (dubbed «Side A» and «Side B»), which when aren’t properly, will render the material toxic for years to come.
3. Spray foam can actually be a fire accelerant. Even when incorporated with a flame retardant (which is toxic in itself), spray foam can still catch fire, and when it does, hazardous fumes are released into the atmosphere.
4. At the heart of it all, spray foam is petroleum-based, which makes it dependent on fossil fuels.
Enter Aerogel
Protected from the flame by a block of aerogel , a flower lies virtually intact.
Fortunately, there are safer alternatives to home and building insulation. The U.S. Department of Energy lists eco-friendly options such as sheep’s wool, fiberglass, cotton, cellulose fibers, and mineral wool. Just to keep things even, it also includes lesser-green and hazardous options to guard against, particularly vermiculite and urea-formaldehyde insulation. (Incidentally, spray foam is not yet on the watch list.)
For sheer building insulation powers however, nothing beats aerogel. Aerogel has been around since the 1930s, and the scientist who invented the stuff, Samuel Kistler, was simply trying to win a bet with a friend that he could take out the liquid in gels & jellies without them collapsing.
The result of his endeavor is a super-material that is actually 99{e3829ec1db02d54faaf9fa2de0d48db26af01d7a7944a63c3b26976124791cab} air, yet still amazingly solid and stable, thus garnering the coolly poetic alias of «frozen smoke«. It’s breathable and fireproof. It’s ultra-lightweight (the lightest man-made material in the world, and–when combined with graphene–becomes even lighter), flexible, and yet can support up to 4,000 times its own weight. And it has none of the toxic chemicals which spray foam reportedly has.
No wonder aerogel has a wide range of use. NASA even uses aerogel to insulate its spacecrafts (which get exposed to extremes of temperatures) and even trap and collect comet debris for study.
As for its use in home and building insulation, aerogel is quite simply a godsend because of its excellent R-value. Silica aerogel, the most popular kind, works well as an insulator because 1. silica poorly conducts heat and 2. aerogel’s molecular structure of nanopores prevents heat from passing through. Being translucent, aerogel also beautifully diffuses light, for that soft, natural daylight we all covet.
For all its benefits, aerogel hasn’t fully made its way into green building insulation because of one critical factor: cost.
Manufacturing this material is a tedious and costly process, and even then, only a small amount gets made with each batch. Until a more commercially viable way of producing aerogel arrives, the only ones who can afford aerogel and take advantage of its wondrous properties are well-moneyed institutions like NASA.
* * *
The Treehugger special on spray foam is certainly eye-opening. Three years earlier, one other building insulation material got a bad critique: polystyrene insulation. Just goes to show that nothing is as good as it seems. Even supposedly-green building materials we’ve all been used to, and which LEED itself approves of, can have their downsides too if only we look closely.
The goal now is to find a truly green and safe way to manufacture and install these building insulation materials.
