Which is a common insulation material used in ductwork?

Fiberglass or foam board is a common insulation material used in ductwork primarily because of its excellent thermal resistance properties. Insulating ductwork helps to minimize heat loss or gain as air passes through. This is especially important in systems that transport heated or cooled air, as any heat exchange with the surrounding environment can significantly affect the efficiency of the HVAC system.

Fiberglass is favored for its lightweight, flexible nature and ease of installation. It can conform to various duct shapes and sizes, providing effective insulation without adding excessive weight. Foam board, on the other hand, offers a rigid solution that is also effective in reducing thermal bridging and maintaining consistent temperatures in the ducts.

Other materials listed, such as wood shavings, concrete, and metal sheets, are not typically used for duct insulation due to their inadequate thermal resistance, weight, or potential for heat conduction, which would lead to energy inefficiencies. Thus, the selection of fiberglass or foam board as common duct insulation options is validated by their performance in energy efficiency and effectiveness in preventing temperature changes in the air passing through.