Insulation is some of the nastiest stuff in construction, as anyone who's gotten fiberglass shards stuck in their skin can attest. The stuff doesn't need to be pretty or pleasant, since it's essentially wall filler. If it's going to stay out of sight, why not make insulation out of any old junk? That's the basic gist of green insulation, which uses recycled materials to line our walls. Cotton insulation is a great example: The soft blue insulation is primarily composed of recycled denim -- aka old jean scraps [source: GreenYour]. Did you ever imagine the material that makes up your favorite pair of pants could also be used to insulate your house?
Cellulose insulation takes an equally common product and recycles it. Any guesses as to the identity of the mystery material? It's the humble newspaper. Recycled paper insulation comes in several forms, but one of the most common is blow-in cellulose, which can be sprayed into walls or attics rather than being laid out in sheets [source: GreenFiber]. Even fiberglass insulation can include recycled glass, but there's a downside: Melting down the glass and forming fiberglass insulation is far more energy-intensive than producing cellulose insulation from paper. Cellulose insulation often consists of 75 to 85 percent recycled material, higher than fiberglass' 30 to 40 percent, and cellulose is even better at preventing airflow than fiberglass [source: HouleInsulation]. Cellulose and cotton are definitely better choices when it comes to green insulation, and neither poses the discomfort or health concerns of fiberglass [source: Bonded Logic].