What’s your air-con costing you?

Posted 19 February, 2026 Andrew Rasch

SA’s January 2026 heatwave was brutal, but most summers are hot across our state.

When the heatwaves hit, your air-conditioning becomes your best friend. Let’s look at how much it costs to beat the heat.

According to the South Australian Government, heating and cooling your house can account for about 40 per cent of your electricity costs and setting your air-con too low or using it inefficiently will spike your next bill. No surprise. It’s a bit like putting Christmas gifts on your credit card. Nothing to pay now, but a bigger bill later.

But a hot house is not only uncomfortable, it’s potentially harmful if you’re younger, older or have health issues. So, whether your air-con is on day and night or only when it’s necessary, what are the running costs, and how can you save money by using it more efficiently?

How do I calculate running costs?

To work out the hourly cost for any appliance, find out its input power in kilowatts (kW) and the electricity rate you’re paying in cents per kilowatt hour (kWh). Then, use the following formula.

Hourly cost = Power (kW) x Rate ($/kWh)

If you’d rather not get out your pencil and paper, this handy online calculator makes it easier. You can also use it to calculate how much your other appliances cost to run. We’ve used this formula to calculate the energy usage of three different air-conditioners: ducted refrigerated, evaporative and split system.

Ducted refrigerated systems are a popular way to cool and heat your house, but they typically use the most energy. Based on a peak rate of 53 cents per kWh, a 12kW ducted refrigerated system costs about $6.36 per hour to run. A 15kW system sees the cost rise to $7.95 per hour, and an 18kW about $9.54.

If we use a shoulder rate of, say, 23 cents per kWh (yes, it can be that much cheaper), those hourly costs drop to $2.76, $3.45 and $4.14 respectively. The shoulder rate typically applies between 10am and 4pm, so it costs significantly less to use electricity during those hours.

Evaporative systems direct hot air through water-soaked pads to cool your home and push it out through an open door or window. They’re generally more energy efficient than refrigerated systems and ideal in SA’s dry heat, but less effective in high humidity. We’ve used the energy input for a typical ducted evaporative system, but you can also buy portable units.

At 53 cents per kWh, a 6kW evaporative system costs $3.18 per hour, an 8kW is $4.24 and a 10kW system costs $5.30.

At 23 cents per kWh, those respective hourly costs drop to $1.38, $1.84, and $2.30.

Split system air conditioners are a non-ducted refrigerated system, most effective in smaller spaces. They’re usually energy efficient and many models heat as well as cool rooms.

With a 53 cents per kWh rate, a 3kW split system costs $1.59 per hour to run; a 4kW unit is $2.12 and 5kW is $2.65.

A 23 cents per kWh rate drops those hourly costs to $0.69, $0.92 and $1.15 respectively.

For the exercise above, we used two different rates per kWh but check your latest electricity bill to see what you’re paying. If you’re on a time-of-use tariff, your electricity is likely cheaper during the shoulder and off-peak periods. Contact your retailer if you’re not sure.

Shop around

If you’re shopping for a new air conditioner, speak to a professional first. The heating and cooling capacity and energy consumption are only part of your decision, but you can check the Energy Rating Label online. The more stars, the more energy efficient the appliance.

How do I cut my air-con costs?

Try these tips and tricks to make your air-con work more efficiently and cut your electricity bills.

• Set your thermostat between 24 and 26 degrees Celsius during the day and around 22°C at night; each degree lower can add up to 15 per cent to your bill.
• Let your refrigerated air-con run, rather than turning it on and off; if you have a modern unit with an inverter, it will adjust its output efficiently to maintain the temperature.
• Use pedestal or ceiling fans to help circulate the cool air; fans typically cost a few cents an hour to run and make your air-con more efficient.
• Close doors, windows and blinds and use door snakes to keep the hot air out; service or clean your air-con’s filters at least once a year to improve their efficiency.
• Compare your energy plan and be prepared to switch; nearly 80 per cent of residential customers could be paying less for their electricity, according to a 2023 Australian Competition and Consumer Commission (ACCC) report.