19Feb External & Internal Insulation Insulation: Insulating ductworks is one of the services that SDF offers to its customers. The most important benefit of insulation is decreasing energy consumption and extending the life of the HVAC system. It will also substantially improve the comfort of the home. Insulated ducts will allow the HVAC system to heat or cool areas more quickly and decrease noises. Acoustic: Another service of the SDF factory is acoustic insulation. Acoustic is an interior insulation used in metal ducts which provides an optimum combination of efficient sound absorption, low thermal conductivity, and minimal airstream surface friction.