When it comes to insulation, homeowners have two main options: cellulose and fiberglass. Both materials are effective for soundproofing and are environmentally friendly, but they have different advantages and disadvantages.
Cellulose insulationhas a slightly higher R-value than fiberglass, making it better at preventing heat transfer and keeping your home cool in summer and warm in winter. It is also resistant to mold and fire, but it is more expensive and has a shorter lifespan.
On the other hand, fiberglass insulation is cheaper and has a longer lifespan, but it is not as effective at preventing heat transfer. Energy Saver and Attic Systems contractors typically inject cellulose insulation to a depth of 17 inches (R-60), completely covering the wooden floor beams which have a low R value and can transfer heat to and from the attic and house. Common sense tells us that cellulose insulation dust is safer to breathe than microscopic glass fibers from loosely filled fiberglass insulation. However, with the low-density fiberglass insulation and loose padding, it is easy to adjust the configuration of the installation machines to inject more air into the hose than material, thus inflating the fiberglass insulation.
A few weeks after the fiberglass insulation has dissipated the air it has generated, the homeowner is left with much less insulation (and R value) than he thought he was receiving. If you pick up a lot of loosely filled fiberglass insulation material, you won't feel much weight or mass in your arms. On the other hand, if you pick up a lot of cellulose insulation material, you'll immediately feel mass or weight. Cellulose attic insulation gets its R value by blocking air flow, helping to prevent uncontrolled air infiltration between the attic without air conditioning and the living room between the attic without air conditioning and the living space.
On the other hand, fiberglass insulation for loosely filled attics doesn't help much to prevent air from entering back and forth between the attic and the conditioned living room. Manufacturers of cellulose insulation materials buy large bales of post-consumer paper and simply convert them into cellulose insulation materials. The Association of Cellulose Insulation Manufacturers (CIMA) states that insulating a 1500 square foot house with cellulose will recycle as much newspaper as a person will consume in 40 years. Millions of homeowners have fiberglass insulation in their attics and their (leaking) HVAC air ducts are in the insulation, and they wonder why they suffer from respiratory problems in their homes.
To sum up, cellulose insulation is better at preventing heat transfer, is resistant to mold and fire, but is more expensive and has a shorter lifespan. Fiberglass insulation is cheaper and has a longer lifespan, but it is not as effective at preventing heat transfer.