Fiberglass can be recycled, and it can be converted into materials that serve as wood substitutes, although many stages of fiberglass production also present opportunities to reduce waste through recycling of unwanted waste products. Despite this, recycling fiberglass is not common, as the majority of recycling centers in the United States do not accept the material.
In other words, it is possible to recycle the material, but it is very hard to find anywhere that is capable of doing so. That said, most modern fiberglass does contain some recycled glass.
Recycling fiberglass is certainly preferable to placing it in landfill, as fiberglass contains formaldehyde, which is extremely toxic. This means landfill sights filled with fiberglass have the potential to become dangerous hazards.
In general, although there are types of fiberglass that do not contain dangerous substances, it can sometimes be better to use alternative materials as insulation, especially in the home.
Sheep's wool, or even old jeans, can be turned into effective insulation that is easily recyclable.
However, fiberglass does have a number of advantages, most notably the fact that it is fire resistant, absorbs sound and it is very effective at providing insulation in homes and businesses. Combined with these qualities, it is also very affordable, making it a cost effective choice for large scale insulation.