“Fiberglass is a man-made product that is composed of natural ingredients such as sand and recycled products such as window glass and bottles (up to 40%). The ingredients are melted and spun to create small strands of fiberglass that together form glass wool.” It is available as loose-fill (blown in) insulation or fiberglass blanket insulation in batts or rolls.
Its other green attribute, like all other types of insulation, is its insulating power that reduces energy use in homes and buildings. “R-value of fiberglass insulation is 3.2 to 3.3 per inch in fiberglass batts and blankets when fully expanded. Loose fiberglass fill (poured or blown) usually exhibits an R-value of 2.1 to 2.7 per inch.” Caulking and sealing of any voids in the building envelope must be performed for maximum energy efficiency.
Fiberglass insulation is naturally non-combustible and it does not require additional fire retardants, but it will melt at high temperatures. However most facings attached to fiberglass insulation are combustible. Fire retardants are added to some facings so that the insulation can be left exposed in areas like basements and crawlspaces. The facings serve as vapor barriers.
Although “direct contact with fiberglass materials or exposure to airborne fiberglass dust may irritate the skin, eyes, nose and throat, studies done in the last 15 years do not provide enough evidence to link this material to any cancer risk.” It is recommended to minimize one’s exposure to fiber glass material.