An insulated duct comprises a free floating liner, an optional bulk insulation layer, a vapor barrier, and a reflective insulation system. The reflective insulation system includes an air gap and a low-e surface. The gap is positioned between the bulk insulation layer and the low-e surface or the outer member and the low-e surface if no insulation is used to gain additional insulating value for the duct. With the free floating liner and the reflective insulation system, a duct can be made to an industry standard R-value while using bulk insulation with a lower R-value.