Think of the building energy rating like the Energy Star Rating on your fridge, basically it tells us how energy efficient a building is and like your fridge the more stars the better. It assess how much energy is used to heat and cool your home and keep it comfortable all year round.
It does this by running your home through a computer simulator and assessing each individual room for every hour of everyday for an entire year and at the end you receive a star rating out of 10 Stars that lets you know how well it performs and highlights any problem areas that need to be addressed.
By having an energy assessor work closely with you during the design phase of your new home it will give you an in depth look into how comfortable it will be to live in and changes made at this point will be a lot easier than later down the track.
The best way to think of it is an investment that will last the life of your home, if you are spending all that money building you really want to make sure that your home is not just architecturally beautiful but energy efficient as well. Having an assessment done will save you money on your energy bills, create a home that naturally stays cool in summer and warm in winter and you will be doing your part for the environment.