Building Cavities Not Used as Supply or Return Ducts Description Guide describing the use of building cavities as supply or return ducts.
Ducts Buried in Attic Insulation and Encapsulated Description This guide describes approaches to buryng and encapsulating ducts in unconditioned attics to increase the overall R-value of duct insulation.
Encapsulated Ducts Description Guide that illustrates how and when to encapsulate ductwork in unconditioned attics, increases the R-value of duct insulation, mitigating condensation issues and reducing air leakage.