Fiberglass insulation is a man-made construction material used to limit thermal changes, as well as sound transmission, in buildings. It is composed of bundles of very thin strands of glass, which has a high surface area-to-weight ratio that makes it a lightweight, cost-effective, and practical option for both residential and commercial applications. Fiberglass insulation is packaged in rolls that are installed along the walls and ceilings of a building during construction.
Though fiberglass as a material has existed since around the turn of the 20th century, the first fiberglass insulation was developed and available for sale in 1938. Initially a competitor to asbestos, the then-standard insulating material, it gained popularity as widespread understanding of the carcinogenic qualities of asbestos grew in the 1960s and 1970s, and forced builders to look for alternatives. With many of the same characteristics as asbestos, fiberglass was a natural option and quickly embraced.
Beyond its relatively light weight and cheap cost to manufacture, fiberglass has a number of intrinsic qualities that make it a good insulating material. The many fibers of glass bundled together are excellent at trapping heat. In this way, a fiberglass-insulated building is far better at retaining a set temperature than a non-insulated one, which means lower energy costs for both heating and cooling. For the same reason, fiberglass insulation is highly effective at reducing sound, and is also non-combustible and non-absorbent. It is important to note that fiberglass also does not wear out or lose efficacy over time.
With roughly 90% of all American homes using fiberglass insulation, and a similar level of popularity across the developed world, manufacturers of fiberglass insulation have responded to increased global awareness about conservation. Therefore, a significant amount of fiberglass insulation is now made using recycled materials. Owens Corning®, the company that first sold fiberglass as an insulation product in the 1930s, began offering insulation in 2009 that contains up to 40% recycled glass.
Fiberglass insulation is not without its negatives, however. Though its proponents contend it is one of the most thoroughly researched products on the market, and point to its recent removal from the International Agency for Cancer Research's list of possible carcinogens, some studies have shown an heightened prevalence of lung cancer among workers in fiberglass factories. Many builders and consumers now choose to avoid it for that unproven, yet troubling, reason.