If you are thinking about duct insulation, you will probably have already looked at fiberglass insulation material. This is becoming less popular as more people become aware of the dangers and difficulties of using this fiberglass in their homes.
While it is undoubtedly a good preserver of heat and much cheaper than the other alternatives, the risk of disturbing the fiberglass, inhaling the tiny shards of glass, or getting them stuck under the skin makes most homeowners reluctant to invest in the material. However, this does not mean you have to do without insulation, as there are many types of insulation which will work just as well.
1. Urethane Foam
This is the most modern of the alternatives to fiberglass duct insulation, and is perhaps preferred by builders and home inspectors as it can be inserted as a foam from a can and then left to harden. This has the advantage that the liquid foam moves into holes that would not be covered by more solid insulation material, but it can also be poured around ducts, insulating them more securely than typical materials. On the downside, Urethane is potentially very expensive and can drive up the costs of any duct repairs you may need in the future. It also needs to be left to dry, making the home somewhat uninhabitable while this occurs.
2. Vinyl Insulation
Like fiberglass, vinyl insulation is often found in a roll, which can end up being simply wrapped around the duct and then sealed with a bit of tape. This can not only look attractive (and who inspects their ducts for visual appearance anyway?), but it also allows hot air to escape between folds in the material. While it can be a suitable alternative to fiberglass, if you are looking to avoid that traditional fiber, it makes sense to go for proper alternatives rather than a mere substitute. Vinyl is probably the cheapest insulation of the methods discussed here.
3. Wood Insulation
A traditional device for keeping the home warm is wood insulation. This is typically understood to mean using a layer of wood inside the log cabin to protect it from drafts. Wood, and particularly bark, can be wrapped around the duct, and either taped in place or secured using caulk. This method of keeping your ducts insulated is a greener alternative than the rest, and if you happen to have available trees, can also be much cheaper. However, it is generally not as effective as the other methods described.
4. Other Green Themes
If you are interested in the idea of using green insulation materials such as wood, but are not sure that it would be suitable for use in duct work, there are other varieties of green substances which can be used to insulate your ducts. Cellulose foam, which is used in insulation, is made out of recyclable materials, but you can also use straw around the ducts, or even old newspapers wrapped tightly around the duct and sealed with caulking.