Ductwork leakage is often, and correctly, cited as the single largest source of causing the most additional energy use in the built environment. Based on a survey of predominately rectangular duct systems, the annual cost of this energy waste runs into the billions of dollars. Engineers, code officials and owners are taking notice and questioning the use of ducted HVAC systems. There is a simple ducted solution, factory fabricated spiral duct and fittings. It has long been recognized that spiral pipe systems leak a great deal less than comparable rectangular systems.