Fiberglass insulation is made of silica sand and recycled glass, both abundant resources. Producing fiberglass insulation requires melting the materials in a fossil fuel–burning furnace, which consumes substantial amounts of energy and generates greater amounts of air pollution than the manufacture of other insulation types.
If installed properly, there is little danger of inhaling fibers, which are throat, eye, and skin irritants. Although the Occupational Safety and Health Administration still requires cancer warning labels on fiberglass insulation products.
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Cotton insulation is made mostly of cotton—a natural, renewable resource—with a small amount of boron as a flame retardant and some polyester. Cotton insulation has a similar R-value to cellulose for a given thickness of insulation.
The majority of cotton used in insulation is recovered from scrap generated in denim manufacturing; one company makes insulation with 85 percent recycled content. Cotton farming is very water- and pesticide-intensive, though manufacturing cotton insulation overall is not a very energy-intensive process.
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Cellulose insulation is made primarily from recycled paper. About 75 percent of the material used to make cellulose insulation is post-consumer waste paper, giving it the highest average recycled content of all insulation types.
The manufacture of cellulose insulation involves a fraction of the energy use and pollution required to make mineral wool and fiberglass insulation. Additionally, scrap cellulose generated during installation can be reused, cutting down on waste.
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Spray Insulation: The chemical insulation agent that is stored in canisters and sprayed into walls, holes and cracks with a special application device; it then expands and dries, forming a barrier. It can be used to supplement existing insulation or plugs leaks. Spray Foam Insulation Problem: Without a radiant barrier, when the roof gets very hot (as in summer), it radiates solar-generated heat down into the attic insulation. Spray insulation primarily reduces heat transfer by trapping warm air. It has a high radiant heat transfer rate and is a very good radiator of this absorbed and retained heat. As surfaces radiate infrared rays in all directions, the heat trapped in spray insulation during the day will radiate down through the ceiling into the air-conditioned living space at night even if the night cools down. [ Read More about Spray Foam>> ]
Mineral wool is made of strands of minerals, either from abundant rock or the recycled slag from iron-ore blast furnaces. The EPA requires that mineral wool contain at least 70 percent recycled content by weight, second only to cellulose. The proportion of recycled materials in mineral wool can surpass 90 percent; look for high recycled content and ask if you don’t see the information displayed.
Though more expensive than cellulose and fiberglass, mineral wool is more durable and moisture-resistant.