Firstly, if you are building a new house or having a large renovation of an existing building then you should use an authentic and experienced green building designer.
If you live in a part of the country that is mostly warm, obviously your house should be designed to be kept cool. If you live in a cool climate you need your house to be warm. However, many parts of Australia have warm and cool climates. Therefore a level of compromise is necessary to get the best of both worlds.
Insulation and intelligent use of thermal mass are vital, as is the north facing aspect.
Something to bear in mind is that when you are living off the grid you will have less available energy in winter and a surplus in summer. This means you maybe be able to take advantage of electric cooling in summer if necessary. With that in mind, if you have any doubts ask the designer of your home to focus on warmth in winter.