Polystyrene Insulation Doesn't Belong in Green Building

A man holds expandable polystyrene insulation material.

Lake Mead NRA Public Affairs / Flickr / CC BY-NC 2.0

As a writer about green design, I hold some opinions that consistently attract tremendous disagreement and abuse; two are heat pumps and insulated concrete forms (ICF) noting that a sandwich of polystyrene and concrete can hardly be called green.

Alex Wilson at Environmental Building News notes another significant problem with polystyrene insulation, found almost universally in structural insulated panels (SIPs) and ICFs: they are full of the toxic fire retardant hexabromocyclododecane, or HBDC.

It is bad enough that polystyrene is made up of the chemicals listed in the chart above, primarily from petrochemicals, but the HBCD is classified under the EU's REACH program as as a chemical of "very high concern" and they recommend that its use be restricted. From Environmental Building News:

Chemist Arlene Blum, Ph.D., who carried out groundbreaking research on flame retardants in the 1970s that was instrumental in the banning of tris and Fryol from children's sleepwear, says that given the very high volume of HBCD use, its persistence in the environment, its toxicity, and that fact that it's being found at rapidly increasing levels in the arctic and in wildlife globally, the chemical "should only be used with caution and when absolutely necessary." She describes HBCD as a semi-volatile organic compound that is not covalently bonded to polystyrene, so she believes that leaching into the soil when in ground contact would be likely. "We need further research to determine the extent to which it can escape during the life of a building," she told EBN.

So really, when people say that things like ICFs are green because they save energy, one can only point out that there are alternatives that are not fossil fuel based and do not contain such toxic chemicals. Alex Wilson suggests a few, including rigid mineral wool and polyurethane insulations. The entire article is worth the price of a subscription, but is now behind the pay wall at Environmental Building News.

Others do not get so worked up about the ingredients in XPS polystyrene, or Styrofoam; Dow recently got Cradle to Cradle Silver certification by McDonough Braungart Design Chemistry even though it is full of brominated fire retardants.

Commenters have also noted that ICFs are good for LEED points, so I clearly don't know what I am talking about:

You sure can earn a lot of LEED points with this type of building material, which "leeds" me to believe that you are overreacting. Or perhaps LEED isn't green enough either?

ICFs get points for energy performance and construction waste management. That doesn't mean they are healthy and doesn't look at its fossil fuel inputs.

I have previously recommended Durisol as an alternative to polystyrene based insulated concrete forms.

Instead of SIPs made with polystyrene, you can get them made with straw.

At Greenbuild I saw quite a few SIPs made with polyurethane foams, which are HBCD free, such as these Winterpanels.

And I have to say, a subscription to Buildinggreen is one of the best investments I have made. After years of abuse manufacturers, installers and users of everything from heat pumps to ICFs, it is such a joy to find that there is an authoritative voice that I can go to for backup and hard data.