Fibreglass is a common form of insulation, but it does have many disadvantages. It is potentially harmful to humans and its effectiveness depends heavily on the climate. For example, if there is a significant difference between the outside temperature and the inside temperate, fibreglass insulation is less effective at keeping the heat inside.
Fibreglass insulation may contain cancer-causing materials. Most of the fibreglass insulation products in the U.S. are sold with a warning explaining there are potential health risks. Inhalation of fibreglass is a serious problem. Inhaling small fibres can cause them to lodge themselves in the lungs, damaging the lungs and affecting the ability to breath. Some fibreglass insulation may have formaldehyde, which may be a potential cancer risk to those installing the insulation.
Fibreglass insulation can settle over time. This causes its effectiveness to significantly drop. An insulation method's effectiveness is measured in "R-value," which measures the ability of heat to pass through the insulation. In fibreglass that has been installed for a significant length of time, the R-value has dropped as the insulation has settled or compacted. While this result applies to most types of fibreglass insulation, some manufacturers claim to have insulation that does not settle over time.
While fibreglass insulation may save energy once installed, the manufacturing process is not particularly green. Fibreglass insulation uses three times as much energy to produce than cellulose insulation, which also has the advantage of being mostly recycled materials. Cellulose insulation is made of 75 per cent recycled newspapers, while fibreglass insulation is made of new materials.
Fibreglass insulation is available in different forms. It may be purchased as a board or batts, and it can be blown in. The properties of fibreglass insulation are slightly different in its various forms. Some forms, such as boards, are less likely to suffer from settling. There are forms in which the inhalation problem is solved by covering the fibreglass with a thin layer of paper that allows vapours to flow freely, preventing moisture build-up.