Ventilation ducts are tubes or channels used in heating, ventilation, and air conditioning systems, commonly referred to as HVAC. They help distribute air throughout a building, ensuring that indoor spaces receive fresh air and maintain a comfortable temperature. These ducts can be made from various materials, including metal, fiberglass, or flexible plastic. Properly designed and installed ventilation ducts improve air quality and energy efficiency by allowing for effective airflow and reducing the need for excessive heating or cooling.