Fabric ductwork has been used in an increasing number of applications. Ductwork is easier to install, compared to sheet metal ductwork, due to reduced weight. Fabric ductwork can promote improved air distribution, with either through use of perforated fabric or discrete orifices. WRL recommends use of fabric ductwork as a low cost displacement ventilation diffuser. Care is needed when designing air-handling unit systems: insufficient pressure will result in sagging ductwork.