The Greenest Insulation
Is one type of insulation greener than another? Definitely. But choosing a type of insulation simply because of its green value might be a big mistake. If this sounds confusing, let’s back up a bit and begin by acknowledging a basic fact: All insulation can be considered green because it plays a major role in saving energy, and there’s no doubt that saving energy is green.
But some types of insulation are considered to be greener than others because of how they’re manufactured. For example, cellulose insulation has a very high green value because it’s made from old newspapers. Turning a waste product into a new energy-saving material is VERY green, but cellulose is also green because relatively little energy is required to turn discarded newspaper into cellulose.
You can buy batt-type insulation (similar to rolls of fiberglass insulation) made almost completely from recycled cotton fiber. Fiberglass batt insulation, on the other hand, contains no more than 30% recycled content. Fiberglass insulation is also more energy intensive to manufacture, because of the high temperatures required to make glass.
Some spray foam insulation also contains recycled plastic content, but it’s usually a pretty small amount (around 10% or so). To make foam insulation greener, some manufacturers are increasing the recycled content and also using soybean resin (a renewable resource) as a partial substitute for resin derived from petroleum products.
The greenest insulation isn’t always the best. Different types of insulation are more suitable than others for certain applications. Cellulose and blow-in fiberglass insulation are excellent choices for attics because they’re affordable and easy to install, and because most attics can accommodate the thick blanket of blow-in insulation necessary to achieve target R-values. But using cellulose in a basement where moisture is present could be disastrous, since paper absorbs moisture easily, compresses when wet, and can attract and support mold.
Spray foam insulation performs better when its air-sealing and gap-filling qualities are important, like when it’s used to seal and insulate the rim joist in a basement or crawl space. If you need to insulate foundation or crawl space walls, rigid foam insulation will be the best choice.
The smartest strategy when choosing home insulation is to match the insulation to the application, then worry about green value. Insulation and its companion upgrade, air-sealing, are “once-and-done” energy-saving improvements. It’s critical to get these upgrades done right the first time. That way, you can be sure of improved comfort and energy savings for as long as you live in the house.