Should I switch the aircon off when I go out?

There is no single break-even time that works for every house. A shaded, well-insulated room and a west-facing room with poor insulation can warm up very differently.

What happens while you are away?

When the air conditioner is running, it keeps removing heat that enters the room. If you switch it off, the room gradually warms and the system needs to remove that accumulated heat when you return.

The system may work harder after restarting. That burst of power does not show that leaving it on all day would have used less energy. Compare kWh across the whole period, including the hours away and the time needed to restore comfort.

For a home empty during a full working day, we suggest switching off rather than maintaining your usual comfortable setting for hours. Australian Government housing guidance recommends turning energy-intensive heating and cooling off when you are out, and using timers or app controls where appropriate.

Make coming home comfortable

Close blinds before strong afternoon sun reaches the windows. Reducing incoming heat gives the air conditioner less work later. A UNSW and RMIT review supports solar control and suitable passive cooling, with the right approach depending on the building and climate.

If your system has a timer or remote control, you can arrange for it to start before you return. Choose a normal comfortable temperature. Setting the thermostat exceptionally low asks the system to pursue a colder room; it is not a reliable shortcut to comfort.

For a quick errand, raising the set temperature rather than maintaining your usual setting may be convenient. How much that saves depends on the room and conditions.

If people or pets remain at home, their needs come first. Plan cooling around who is there and how hot the home becomes, rather than applying an empty-house rule.

What about heating in winter?

The same question applies when the reverse-cycle unit is heating. Warmth escapes through the building, and keeping an empty home at the usual setting uses energy. For a long absence, use the unit’s schedule to suit your return and check how the home responds.

A room that gets cold quickly may need attention to draughts, insulation or window coverings as well as the heater. Compare comfort and energy under similar conditions. There is no universal number of minutes away that settles the decision for every home across the region.

Consider the price and the energy separately

A solar household or a time-of-use customer may sometimes benefit from cooling earlier, when electricity is cheaper. A home that holds its temperature well may retain some of that comfort into the evening.

That can reduce the cost of cooling during an expensive period. It does not establish that every form of pre-cooling uses less energy overall.

Try a modest schedule over several days with reasonably similar weather. Record the hours away, settings, comfort on return and other large appliances. Compare kWh and electricity cost separately. One unusually hot or cold day can distort the result.

The practical starting point is to switch off for a long absence, reduce heat entering the home, and use the controls you already have to suit your return. If the room becomes uncomfortable very quickly, it may be worth getting advice about shading, insulation or the system’s suitability before buying more cooling capacity.

For a fair household experiment, compare several occupied days with similar outdoor conditions and the same comfort target. Alternate the schedules rather than assigning all hot days to one option. Record the full period, including cooling before you leave and after you return. Keep any comfort or health needs ahead of the comparison.

Related advice: How much power does an air conditioner use? · What should I electrify first?

Make the next step fit your home

Our energy-saving tips (opens in a new tab) offer more ways to manage comfort and usage, whoever supplies your electricity. If a heating replacement is the next job, explore our heating and cooling upgrade page (opens in a new tab) and check eligibility before requesting a quote.

See what you can save with Electrify (opens in a new tab)