Ductwork is the system of tubes, channels, and passageways that distribute heated or cooled air from furnaces, air conditioners, or heat pumps throughout buildings. Ducts are typically made from sheet metal, flexible aluminum, or fiberglass board, running through walls, ceilings, floors, and attics to reach rooms via registers and vents. Proper ductwork design ensures adequate airflow to all spaces while minimizing energy loss. Leaky or poorly insulated ducts can waste significant energy, as conditioned air escapes before reaching its destination. Municipal buildings require properly designed ductwork for occupant comfort and energy efficiency, and building codes specify requirements for duct materials, installation, and fire safety (ducts can spread fire and smoke between rooms if not properly designed). Regular maintenance includes filter changes and periodic cleaning to maintain air quality.