The Resources and Energy Minister, Martin Ferguson, is reported to have proposed households receive discounts on their electricity bills for reducing consumption during annual peaks ("Low-energy households should be rewarded", AAP, Trading Room, August 10 2012, 6:10PM). He pointed out that 25% of the retail power cost was to cover 40 hours of peak use a year. Giving consumers an incentive to reduce use during those 40 hours would reduce the need for infrastructure which remains idle the rest of the time.
Giving consumers an incentive to manually switch off to save money has not worked in the past and there is no reason to think it will work now. What has worked is a discount for appliances which automatically switch off at peak times (called "demand response"). Off peak hot water systems have been in use for decades. I suggest this technique be applied to air conditioners and space heaters.
I suggest that large energy consuming "dumb" air conditioners and heaters be banned, under existing legislation which regulates the importation and sale of electrical devices. Air conditioners and heaters would be required to have a low power mode which can be switched on remotely at times of peak demand, with no action required by the consumer.
Such a ban would not effect the sale of small air conditioners and heaters which plug into an ordinary power point, only larger units which have to be directly wired into the household electricity supply. The large units would not switch off completely during peak periods, but go a low power setting where they consume only as much power as a plug-in unit (2400 Watt). The fans of the air conditioner/heater would continue to operate for the few minutes it was in low power mode and it is likely that the householder would not notice the difference. In a prolonged peak, a smart unit could be programmed to direct all the cooling or heating to one priority room of the house.
With old off peak systems, the signal to hot water systems was sent out over the power lines. For a modern system the Internet could be used. This need not use the NBN, but the Government might find it useful to promote the NBN as an energy saving tool.