Installing insulation in your home is one of the most cost effective measures you can take to help you stay warm and winter and cool in summer.  It’ll mean that you stay comfortable naturally for a lot longer and can greatly reduce the amount of time that you do need to use an air conditioning and/or heating system. 
Insulation works by creating a barrier to heat transfer through ceiling, walls and in some cases, floors.  In summer it helps keep your home cooler by reducing the amount of heat entering your home.  In winter it helps keep your home warmer by trapping the warm air inside. 

See the diagrams below for an indication of typical heat lost during winter and heat gained in summer in a temperate climate.

For best results, all ceilings, walls and raised walls should be insulated, and the best time to do this is at construction.  Insulation can be added to existing buildings with varying effectiveness and cost depending on the construction type and where the insulation is being placed.  Retrofitting insulation is generally very common in Alice Springs as many houses were not insulated at the time of construction (though it is often difficult to retrofit insulation in walls).

Types of insulation

There are two main types of ceiling insulation - bulk and reflective foil.  The right type for your home will depend on the type of ceiling cavity, access available to the ceiling and personal choice.

Bulk insulation mainly resists the transfer of conducted and convected heat, relying on pockets of trapped air within the insulation.  Its thermal resistance is essentially the same regardless of the direction of heat flow through it.

Bulk insulation includes materials such as fibreglass, rockwool, wool, cellulose fibre (shredded newspaper treated with flame retardant), polyester and polystyrene.  For houses that have minimal ceiling cavity, including cathedral ceilings, ‘blow in’ insulation (such as cellulose fibre) can be an appropriate solution.

Reflective foil is generally installed under the roof surface and mainly resists radiant heat flow due to its high reflectivity and low ability to re-radiate heat.  It relies on the presence of an air layer of at least 25mm next to the shiny surface.  The thermal resistance of reflective insulation varies with the direction of heat flow through it and generally is more effective at keeping heat out in summer, though it does reduce heat loss in winter.

A range of composite materials are also now available - bulk and reflective materials are available that combine some features of both types.  Examples include foil backed blankets, foil backed batts and foil faced boards.

For a summary of different types of insulation and applications, click here.