RACV Solar’s regional manager of heating and cooling, Tom McKenzie, says air-conditioners have come a long way in recent years in terms of energy efficiency. “An old unit might need around six kilowatt hours of electricity to cool an average-sized house, while modern air-conditioners can cool the same house for less than a third of that,” he says. So, if your air-conditioner is more than 15 year’s old, it might be worth taking advantage of state government incentives to upgrade to a newer, more energy efficient system. The Victorian Energy Upgrades program offers householders rebates of up to $1100 for replacing old systems with new energy efficient, reverse cycle air conditioners.
When choosing a new system be sure to check the energy star ratings on the Federal Government’s energy-rating website. The more stars, the cheaper the running costs. And remember, if you have roof- top solar, you can run the air-conditioner during the day using power generated from your roof, without running up your power bills.
Wall-mounted reverse-cycle split systems
One of the most energy efficient cooling options for your home, these all-in-one heating and cooling units, pump hot air from inside your home to an external refrigeration unit in summer and return chilled air inside. In winter the same system heats the air before pumping it back inside.
Although new split systems are relatively cheap to run, the Australian Energy Foundation warns that for every degree you lower the thermostat, you’ll add 10 per cent to the running cost – with minimal extra benefit to your comfort level. The AEF recommends setting the thermostat at 23 to 26 degrees in summer, to minimise your energy usage.
- Upfront cost: Each unit will cost at least $2000, including installation, to cool up to 20 square metres, and more than twice that for a powerful unit that can cool 80 square metres. So, if you want to cool more than a couple of rooms, you may be better off investing in a single ducted system that can chill the whole house.
- Running costs: From 36 to 70 cents an hour, depending on the unit’s energy rating and size of your room. Of course, if you have rooftop solar, you can power your air-con during the day without running up your energy bill.
- Pros: The same system will heat your house in winter.
- Cons: Each unit will cool just one room so if you want to cool the entire home, you’ll need a unit for every room.
- Best suited for: Cooling one or two selected rooms – such as a bedroom and a living room.
Ducted split systems
These work in a similar way to wall-mounted split systems, but pump chilled air back into the house via ducts in your floor or ceiling. They are also fairly energy efficient but more expensive up front, costing $10,000 or more to buy and install. Many ducted systems now come with ‘smart’ features that allow you to adjust the temperature and turn cooling on and off in certain rooms or sections of your house remotely using your smartphone or laptop. This allows you to turn on the air-con remotely to keep your home cool before it really heats up. Not only will you arrive home to a comfortable temperature, you'll avoid the extra energy use needed to chill a stinking hot house.
- Upfront costs: Smaller ducted systems start at around $10,000, including installation.
- Running costs: Expect to pay around 36 to 70 cents per hour, per room, or $2.45 to $3.45 per hour if you’re cooling a whole 200-square-metre house.
- Pros: You can choose to cool the whole house, or just the rooms you’re using.
- Cons: Relatively high up-front investment.
- Best suited for: Larger family homes where you want to cool several rooms at once.