Insulation

The green choice is obvious: you want insulation that insulates. So far, so obvious. But there’s definitely more to consider, mainly in the things that manufacturers don’t tell you in their glossy literature. They always publish the “R-value”, which tells you how much that material will resist the flow of conductive heat. If the manufacturer followed the standardized test and used an independent third party, then you do have a pretty good apples-to-apples comparison with competing materials.

But hold the phone, consumer. The R-value is only a rough indicator of how well something will actually help keep you comfortable. Batt insulation will settle and compress over time, and is very hard to get into every little void, so you end up with a lot of uninsulated places. Batt and rigid insulations need to be well sealed—a difficult job—or air can move around them and compromise their effectiveness. For wood-framed walls, floors and roofs, only spray foam insulation can and will really fill the cavity (though it’s relatively easy, and usually a good idea, to place a layer of rigid insulation outside the framed assembly). And all insulations vary in their effectiveness with age, with outside temperature, with exposure to moisture and/or vapor, with workability (is it easy to change the wiring or plumbing?), and with the quality of installation.

Finally, there are questions around chemicals: some insulation comes from pretty toxic sources, and some are still giving off toxins when installed in your home, or even months and years later. That’s a lot to consider, but it’s worth getting right: good insulation is to your health and energy bill the gift that keeps on giving.