About three weeks ago I posted here about a product that decreases heat loss, decreases installation time, provides a termite shield, prevents damage, is cost-competitive, and is partly made with PVC. We ended up listing this product in GreenSpec, and to our members' credit, we got some pushback. I cross-posted a response from the members-only system to the public comments of the earlier blog post; now we've received another thoughtful member comment, so I figured I'd bring the concern back here to the blog to hear what you smart people have to say. A BuildingGreen Suite member wrote to suggest that this product, and any others containing EPS, should be reconsidered for potential removal from GreenSpec due to the use of hexabromocyclododecane (HBCD), "a persistent, bioaccumulating, and toxic fire retardant [...] widely detected in household dust, sewage sludge, breast milk and body fluids as well as wildlife and the global environment. [... P]olystyrene insulation [...] is likely the primary source of the global contamination." What a great comment. What a can of worms. I wrote back:

Another mighty important subject. As noted in the Environmental Building News article, Insulation: Thermal Performance is Just the Beginning, "All foam plastic insulation materials rely on flame retardants to meet fire-resistance standards. EPS and XPS are produced using the brominated flame retardant HBCD (hexabromocyclododecane) at concentrations of 0.5-2.0% by weight. HBCD is not the focus of as much attention as another class of brominated flame retardants (PBDEs), but some evidence indicates that it is more bioaccumulative than PBDEs and just as likely to be toxic to humans." It then refers to another EBN article, Flame Retardants Under Fire, which goes into additional detail about HBCD: "Hexabromocyclododecane (HBCD) — the third most widely used brominated flame retardant in the world and the BFR of choice for polystyrene foam — may actually be more prone to bioaccumulation than PBDEs. HBCD is just as likely to be toxic to humans, according to an October 9, 2003 article in the American Chemical Society's journal, Environmental Science and Technology. The Chemical Stakeholders Forum in the U.K. determined in March 2003 that HBCD is persistent, bioaccumulative, and toxic. The European Union is carrying out a risk assessment of HBCD, suspecting the compound of being an endocrine disruptor by impairing thyroid function." (It's interesting to note that Europe, having taken steps to ban penta and octa PBDEs, was in 2001 using more HBCD than the Americas, Asia, and the rest of the world together. I don't know if that has changed.) The problem is on our radar. The real difficulty comes in weighing the overall consequences of using a product with flaws versus not using it (when an equally viable alternative doesn't exist). Foamed glass insulation seems like it could be a great alternative for high-moisture applications, if only it were affordably — or even just readily — available in the Americas. Canadian manufacturer Roxul has mineral wool products that could do the trick, but they're almost impossible to get in the US. If I'm missing some obvious solution, I hope somebody will speak up. There was a timely conversation during the most recent GreenSpec review meeting. We were talking about glazed curtain walls, which are basically an energy catastrophe when weighed against other design options. (So why are all these big green high-rise projects being specified with glazed curtain walls?) The question came up: Even though GreenSpec only lists the highest-performing glazed curtain walls that set the bar for energy efficiency, should it be listing any of them at all? Discussion ensued. What is GreenSpec for, and how does it support the BuildingGreen mission of transforming the building industry? Should we put our energies toward supporting the bleeding edge, or toward facilitating change in the larger (perhaps less committed) green building community? The answer was that we need to continue trying to do both. It ain't easy. GreenSpec is intended to be a best-of-the-best directory, a starting point for further research — that's why each listing is accompanied by links to related information in BuildingGreen Suite, like the two articles I cited above. We've also been working behind the scenes to beef up the section introductions with deeper and more concise information about categories of products, and thinking about how to make that too-often-overlooked bigger picture more visible and accessible. Conversations like this are a definite help in that effort. So, back to slab edge insulation. Uninsulated slab edges can account for more than 10% of a home's heat loss. This is particularly exacerbated when "green-friendly" radiant-floor heat is used — the Radiant Panel Association says, "Slab edge insulation is a given. No one should be installing a radiantly heated slab, basement or on grade, without this important piece of insulation." (Why did I put "green-friendly" in quotes when talking about radiant floor heating? See the article Radiant-Floor Heating: When It Does — and Doesn't — Make Sense.) Uninsulated slab edges are a problem requiring a solution. This particular product, despite its incorporation of undeniably nasty materials like PVC and HBCD, can prevent significantly more toxic emissions and environmental degradation over their service lives by reducing energy consumption than if they weren't used. Deciding which side of the coin represents the worse consequence is no easy feat — this one's almost a lose-lose situation. As the article Building Materials: What Makes a Product Green? says, "The Holy Grail of the green building movement would be a database in which the life-cycle environmental impacts of different materials were fully quantified and the impacts weighted so that a designer could easily see which material was better from an environmental standpoint. [...] Very often, we are comparing apples to oranges. We are trying to weigh, for example, the resource-extraction impacts of one product with the manufacturing impacts of another, and the indoor-air-quality impacts of a third." On a note related to HBCD, the foam cushioning used in some furniture and lots of car seats can be up to 30% HBCDs (compared to 0.5-2.0% in rigid insulation). Especially as the foam ages and it becomes increasingly friable, HBCD-laden dust can be released directly into the room's air as people sit down, get comfy, stand up. It's even more acute when the fabric is ripped. There's also foam carpet padding to consider — the dust works its way up through the carpet when it gets walked on, thrown into the air when vacuumed... Which isn't meant to be an excuse. Just one more thing to think about. Here's another one that gets into PVC and flame retardants, if you'd like — Wire and Cable: Untangling Complex Environmental Issues. Thanks for your important note, and do keep up the good work. Please feel free to continue this dialog and to point out other concerns as you come across them.

For more about HBCD, see the Environmental Health Perspectives article, Brominated Flame Retardants: Cause for Concern? We're always willing to entertain doubts. Did we go too far in including this product?