One easily-avoidable bad habit will see a quarter of Australian families waste $578 each this summer.
Close to a quarter of Australians admit to leaving their air conditioner running when they're not home, according to a Finder survey of 2017 Aussies, which amounts to 2.3 million households and a national spend of $1.3 billion on cooling empty homes.
The survey found those either forgetting to turn their air con off, or just wanting a frosty reception when they get home, are wasting an average of 4.1 hours in energy per day.
A significant amount of money, considering energy prices have shot up 80-90 per cent in the last decade and sit at record highs, and heating and cooling is responsible for 40 per cent of household energy use, according to the Australian Government's YourHome guide.
Those with a typical split cycle air conditioning unit will be interested to know it consumes about 5kWh and costs around 2.7?? to run per minute, according to Finder. In turn this means it can cost close to $13 per night if you leave it running overnight.
But all is not equal across the population, with Generation Z (18-22-year-old) Aussies the least thrifty with the air con remote. Baby Boomers were the second-most wasteful generation, followed by Millennials and Generation X were reported to be the least wasteful.
The study found women to be slightly more prone to air con over-indulgence, wasting on average 253 minutes per day, compared with 233 minutes from men.
"We know that cooling and heating make up the largest share of the average Australian household's energy use, accounting for around 40 per cent, which means they are also big drivers of the cost of our energy bills," Australian Energy Regulator acting chairwoman Cristina Cifuentes told Domain.
"To avoid a nasty surprise when the power bill arrives there's a number of steps people can take to keep things manageable.
"Using air conditioning wisely is key - if you run it while you're out, you may well come home to a cool house, but you will pay for it down the track."
Ms Cifuentes added that consumers should make sure they are on the energy plan that best suits their circumstances, and be aware that some deals charge differently depending on the time of day.
Meanwhile running a home air conditioner just one degree warmer than you normally would can cut cooling costs by about 10 per cent, according to Energy Australia chief customer officer Kim Clarke, who told Domain that energy use can spike in the evenings as people return home.
"Depending on the severity of the weather, electricity demand might be 10-30 per cent above average," Ms Clarke said.