The ventilation ducts need to maintain heat loss and also balance the air temperature while transporting hot air through the ducts.

In the case of cold air the ducts need to maintain a lower temperature inside the duct and is maintained by the warm insulation of the duct.

If the insulation is not appropriate then the HVAC system will take up a lot of heat as well as mechanical energy and the system’s functioning will deteriorate.

Fibreglass insulation is similar to sheet metal ducts but contains an additional insulation of fibreglass in the interior or exterior. It is used mostly in commercial places or big buildings and provides sound attenuation by dampening the noise from the air conditioner. Fibreglass lined ducts are relatively hard to clean and can pose certain health problems. When it is insulated in the interior part of the duct, it is very hard to clean and can become wet and harbour moulds and bacteria. These ducts can degenerate and release fibreglass particles that are extremely harmful for lungs.

Another kind of insulation is Fiberboard insulation which is made from glass fiber that are compressed and bonded into boards with resin and are covered with a foil sheet to prevent moisture build up. These ducts are good for air conditioning systems as they are well insulated.