NatHERS modelling splits homes into conditioned and unconditioned areas.  Conditioned areas are those rooms in a dwelling that are usually heated or cooled, so living rooms, bedrooms and kitchens.  Unconditioned areas are those rooms that are usually not heated or cooled, like bathrooms and laundries.

Garage areas are usually considered to be unconditioned spaces and are usually not included in the calculation of total floor area for a dwelling.

Block sizes have been getting smaller in recent years.  These charts show the average block size by state and territory.

Insulation products are given an "R-Value" which is an indication of the products resistance to heat transfer, that is, its thermal resistance.  The greater the R-Value, the greater the resistance to heat transfer, and the greater the insulating effect and subsequent energy savings.