Power in WA was subsidized by the state government for many years, that is why we are now crying at the actual cost of power generation, which is the unhappy of price of over 24.5 cents per Kw/h. But Australia is an interesting place, where it can exceed 40-odd degrees and people become quite irritable when hot and overheated, but curable with expensive air conditioning, but this upsets you and your accountant.
So the fact is that are you hot and irritable enough to turn on the AC, and allow it to motor through the power? Or are you able to withstand the heat, and keep your accounts in check. This is a question only you can answer. But there are few things that you can do to keep everyone happy. Most of them a widely sprouted, and well known, but together they can have a tremendous impact.
Turn your air conditioner on early before the heat of the day sets in or a timer that allows the AC to turn on at 12.30, as the coolness of the house is maintained, and your AC is not having to fight the heat when you get home. It sounds expensive to run you AC from the morning, but it is not working hard as all it is doing is maintaining the coolness, 25% load for example, opposed to 100% when you get home and depending on the size of the home, for the next 2-3 hours. Plus, you have the benefit of having your home nice and cool when you get home.
Also, if you raise the temperature to 25 degrees while you are at work/away for the day, you will consume less power as you are maintaining a higher temperature, and lower the temp to 23 deg when you get home, to give it the pleasant cool touch if you wish, as you are only countering a 2-degree difference, opposed to a 20-degree difference in a hot 40 deg home.
Solar energy. A standard 1.5kw solar system has the ability to power 2x 2.5kw air conditioners, on full sun. By having your home cooled by solar power (indirectly, but it is), you are cooling you home for free. This allows you to have a more comfortable lifestyle where you can run the air conditioner on a hot sunny day. Naturally, the larger the system, the more you will be able to power. But, if you have a small 2.5kw air conditioner, TV and a few other items, you will be drawing from synergy, but it will be comparatively minimal if you did not have solar. This keeps you happy, and Western Power is not struggling to power Perth.
Evaporative Air conditioning. Evaporative air conditioning uses considerably less power than refrigerated air conditioning. A large evap, for large homes might use 1000-1500w, opposed to the 5500-7000w that will be consumed on running a reverse cycle ducted system. The only large consumption of resources that an evap uses is water. But, water is $1.44 per 1000L of water. which might be the total water used in 1 year if used in summer. Though evaps in equatorial climates or humid areas such as the north of Australia, are not effective as the air is already humid. But for Perth they are a fantastic alternative to the power hungry refrigerated systems.
As stated, they are well known and somewhat over touted methods of saving energy, but in practice, they are the main methods of reducing power consumption for air conditioning, as you still need X amount of energy to remove Y amount of heat, a main principal of thermodynamics and heat pumps, but common sense is the key. Closing the door to rooms no one is in, so why cool it?