It is really hard to get people excited about insulation. As Tedd Benson says in the introduction to BuildingGreen's Guide to insulation,
It’s invisible and boring. Like reinforcement in concrete, it’s often seen as kind of a cost nuisance rather than something you’d want to consider improving. Similarly, “out of sight, out of mind,” aptly explains why people don’t give much consideration to insulation.
But it is probably the most important factor in the design of a building. Tedd notes:
We can literally insulate our way to a much brighter energy future while insulating our- selves from the ever-higher cost of energy. Every highly insulated building is an energy miser forever. Every building weaned from fossil fuels is weaned forever.
Unfortunately, it is incredibly complex and confusing, and the more I read, the more confused I get. Alex Wilson, the author of the guide, says
“No other building element offers such a diverse range of materials and complexity of considerations—environmental, human health, performance, and building science.”
It used to be, all one cared about was the R-value, the resistance to heat flow; the more the merrier. But it is not so simple; now one worries about embodied energy and carbon, the global warming potential of blowing agents, the dangers of added flame retardants, deconstruction and end of life issues. Making a choice of insulation is such a complicated set of trade-offs.
That's why I read the Guide to Insulation Products and Practices from BuildingGreen in one sitting as if it was a novel; it pulls all of this complicated and contradictory information together and holds your hand as it guides you through, explaining how insulation works, the health and environmental considerations, performance and durability, different types, ending up with tables comparing the key environmental performance factors and finally, the bottom-line insulation material recommendations.
My favourites, polyurethanes, are offgassing, chlorinated, toxic and contribute to global warming. They forgot to mention that they are also a serious fire hazard.
These are controversial issues; I have almost come to blows over them, complaining about global warming potential of blowing agents to people who claim they are selling a "green" product that saves so much energy that it will help stop global warming. When one complains about formaldehyde binders in fiberglass, they will respond that it has Greenguard certification, don't I know anything? And don't even try to have a discussion about toxic flame retardants, they save lives after all.
In fact, I have met few outside of the BuildingGreen people who even acknowledge these issues, instead concentrating on the premise that "saving energy is green." The BuildingGreen guide, on the other hand, addresses all environmental concerns, not just energy. Nobody is perfect; even that blue denim insulation that advertises with kids lying on unprotected batts is treated with borate flame retardants, which have been
thought to be benign, but health concerns are not well known; in 2011 the European Union added boric acid to the “Candidate List” of potentially toxic chemicals in its REACH program, with concern about reproductive toxicity.
So am I now completely confident about my options for insulation? No, and I still don't have a complete picture. I am still completely confused about vapour barriers, that I was taught were critically important; Alex barely mentions them, and suggests that they may even be a problem because they impede moisture flow. There is no guidance at all about what to do in renovations, which are going to be probably a much larger proportion of residential construction in the future. Finally, and perhaps most importantly, insulation is just one component in a wall assembly, and so much can change depending on how it is detailed and used. There are no details or drawings; while it is called a Guide to Insulation Products and Practices, It is much more of the former than the latter.
Tristan Roberts writes in Environmental Building News that the report "acknowledges that there are no universal right or wrong answers for every project. Instead, it offers guidance to support appropriate material choices—as well as best practices—depending on the project and the budget." I suppose that is as close as we will ever get to a definitive guide to such a complicated subject.
BuildingGreen does not accept advertising and is completely user-supported, so their products are not cheap; the insulation guide is $99 for subscribers (which everyone in the biz should be) and $ 129 for others. But it's worth every penny if you want to understand how dig through the mess of complicated and conflicting information about insulation. R value is just the start. Order it here.