If your air conditioner is running when no one’s home, or set to Arctic levels just to feel cool, you’re not alone. Many Australians set their air conditioning lower than necessary, then forget to turn it off when they leave the house, quietly driving up their power bills over summer.
Research from comparison website Finder shows that around one in four households leave their air conditioner running when no one’s home. Applied nationally, that’s the equivalent of millions of Australian homes cooling empty rooms, and it adds up to significant, unnecessary energy use each year.
Energy experts say the issue isn’t that Aussies use air conditioning — it’s how they’re using it.
With heatwaves already hitting parts of Australia and electricity prices continuing to climb, experts say small changes to air con habits can make a noticeable difference to summer power bills, without sacrificing comfort.
The cheapest way to run your air con this summer
- Set the temperature to 25°C
- Use medium fan speed for better efficiency
- Only run it when someone is home
- Close blinds and curtains during the day
- Use a fan to circulate cool air instead of lowering the temperature
“Aussies can reduce their cooling costs by simply setting their thermostat to 25 degrees,” says Graham Cooke, energy expert at Finder. “You don’t need to blast your aircon to the point where your home feels like Antarctica.”
Typically, most households set their air conditioner to around 22°C. But according to Finder, adjusting that setting alone could reduce cooling costs by up to 30% over summer.
The most common air con mistakes Aussies make
Setting it colder than necessary
Many people assume lower temperatures cool a room faster, but experts say temperatures below 24–25°C usually waste electricity without improving comfort.
Leaving it on when no one’s home
Finder’s research shows Aussies leave their air con running for nearly an hour a day when the house is empty, adding unnecessary costs over summer.
Using low fan speed by default
While low fan speeds use slightly less electricity, they can reduce cooling efficiency unless the weather is particularly humid.
What temperature to set the air conditioner to in an Australian summer
“Research shows the most comfortable temperature for the human body is around 25 degrees,” says Cooke. “Anything lower means you’re cooling beyond comfort.”
He adds that while low fan speeds may feel gentler, medium fan settings generally cool rooms more evenly and efficiently. Low fan speeds are best reserved for very humid conditions.
Other low-cost ways to stay cool
“Don’t write off your fan just yet,” says Cooke. “Using a fan alongside your air con helps circulate cool air around the room, meaning you don’t need to set the temperature as low.”
He also recommends placing fans near windows at night to draw in cooler air and keeping blinds and curtains closed during the day to block out heat from the sun.
Portable air conditioners worth considering
For households without ducted air conditioning, or those looking to cool a single room without running the whole house, portable air conditioners can be a practical option when used efficiently.
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