Renew.org.au has outlined (20/03/2014) the ways in which insulation can help combat Australia's hot summers and cold winters.

Home insulation can dramatically improve the level of comfort in the home during weather extremes simply by reducing the flow of heat into and out of the home.

A home with sufficient home insulation will retain heat in winter with far less energy input than an uninsulated home.

Similarly, in summer, a home that is well insulated will take longer to warm up. Adequate insulation also mean less energy is required to cool a home when the air conditioner is used.

Insulation can actually slow down the cooling down process of the house if there are too many windows with high solar heat gains. These windows need to be shaded, especially if west facing.

The most common type of home insulation is bulk insulation which is used to reduce conductive heat transfer.  The batts are made from many materials including glass fibre, polyester fibre and sheep's wool.  Installed properly, these materials reduce the rate of heat flow as they are such poor conductors of heat.