Duct insulation material and method of using

A flexible insulation material surrounding an HVAC duct defining an airflow passage therein, the flexible insulation material comprising:

• a substrate containing nonwoven lofted fibers, the flexible insulation material being attached to the duct such that a first surface of the substrate faces an exterior wall surface of the duct;
• and
• first and second facer sheets laminated to, respectively, the first surface of the substrate and a second surface of the substrate oppositely disposed from the first surface, wherein the first facer sheet faces the exterior wall surface of the duct and is spaced apart from the duct to define a substantially continuous air gap therebetween, each of the first and second facer sheets comprising a polymeric film bonded to the substrate, a metallization layer on the polymeric film and separated from the substrate by the polymeric film, and optionally a corrosion-resistant protective coating on the metallization layer;
• wherein the flexible insulation material is secured to the duct and provides thermal insulation and sound attenuation properties, and the nonwoven lofted fibers of the substrate are contained between the first and second facer sheets to prevent the nonwoven lofted fibers from being released from the flexible insulation material.