Best Air Conditioner Temperature for Energy Saving in Australia

Every Australian household has had the same argument. Someone bumps the aircon down to 18°C on a hot afternoon to cool the room down faster, while the other person quietly cranks it back up to 24°C to avoid a heart attack when the power bill arrives. Sound familiar?

The reality is that your temperature setting is one of the single biggest levers you have over your electricity costs. A few degrees of difference can mean hundreds of dollars by the end of a hot summer, or a mild winter spent running the heater in heating mode. And yet most people have never been given a clear, simple guide to what temperature to actually set it at.

This article answers that question directly, based on guidance from CSIRO researchers, energy experts, and major manufacturers. We’ll also walk through how much your system actually costs to run, and practical ways to slash that figure without sitting in a sweltering room.

How Much Do Air Conditioners Cost to Run?

Before you can manage your aircon running costs, it helps to understand what’s actually happening on your power bill.

Heating and cooling appliances account for about 40% of energy use in the average Australian home. That makes your air conditioner one of the most significant contributors to your electricity bill, which means it’s also one of the biggest opportunities for savings.

The formula for calculating running cost is straightforward:

Running Cost = Input Power (kW) × Electricity Rate ($/kWh) × Hours Used

The “input power” is the actual electricity your unit draws, found on the energy rating label or the unit’s spec sheet. This is different from the cooling or heating capacity (also measured in kW), which is always higher. Annual aircon running costs in Australia typically range from $50 to $583, depending on the unit size, location, and how you use it. 

Here’s a practical breakdown to give you a rough sense of the numbers:

Based on NSW electricity rates of approximately $0.30–$0.35/kWh. Actual costs depend on your tariff, insulation, and usage patterns.

Modern inverter models are smart, they ramp down their power use once the room hits your set temperature, so your actual cost is often lower than the top-end estimate.

One comparison worth flagging: split-system air conditioners’ actual running costs may be even lower in practice, as inverter models adjust their output as needed, so in a well-insulated and well-sealed house they can maintain a comfortable indoor temperature while running at very low power. 

What’s the Best Aircon Temperature for Summer?

This is the question people ask most often, and the answer is more specific than you might expect.

For houses in Australia, the most efficient temperature for AC in summer is generally 25°C to 27°C. This range keeps your home cool and comfortable without higher energy use. Setting your temperature much lower than this won’t cool the room faster, instead, it forces the unit to work harder and increases your running costs. 

Here’s the key principle to lock in: each degree cooler you set the thermostat can add about 10% to the running cost of your air conditioner. 

That’s not a small number. If you set your system to 20°C instead of 26°C, you’re potentially doubling your running costs for that session. Over a Central Coast summer that can stretch from November through to March, that adds up to a genuinely significant amount on your power bill.

The 8°C Rule

Experts recommend trying to keep the temperature difference between inside and outside to around 8°C for maximum efficiency. So on a 32°C day, set your air conditioner to around 24°C. Every degree above that 8°C difference adds 10% to your air con running costs, and over a long, hot summer that will really add up. 

This doesn’t mean you have to suffer through 30°C-plus days sitting at 26°C. On extreme days you’ll want to go lower, just be aware that the cost increases as you push the differential wider.

CSIRO researchers note that the most energy-efficient action is to set the temperature to the highest value that’s still comfortable, 26°C during the day is often recommended, and then just let it run. Modern inverter units will adjust their output efficiently to maintain that temperature. 

The Blast-and-Off Myth

A lot of people think they’ll save money by blasting the aircon at 17°C or 18°C to chill the room quickly, then switching it off and repeating later. This feels thrifty but it’s not the most energy-efficient choice. It requires a lot of energy to get a room to a very chilly temperature, and repeatedly doing this throughout the day isn’t wise. 

A far better approach: set it to a moderate temperature (25–26°C), let the inverter do its job, and use a ceiling fan to help circulate the cool air so the room feels comfortable at a higher set temperature.

What Temperature Should I Set My Aircon During the Day vs. Night?

During the day (occupied rooms): 24°C–26°C is the sweet spot for most Australian homes in summer. This keeps the ideal room temperature comfortable while keeping your electricity use in check.

At night for sleeping: Most people sleep comfortably between 18°C and 22°C, but setting your aircon that low all night is expensive. Use the in-built timer to cool the space before going to bed, around 23°C, and your room will reach the desired level perfect for a good night’s sleep. If you use a sleep or timer mode, the system can gradually allow the temperature to rise slightly once you’ve drifted off, which saves energy without disrupting your sleep. More on the ideal sleeping temperature in the FAQ below.

When you’re out: If you’re leaving the house for more than an hour or two, turn the system off rather than leaving it running. The energy cost of cooling the house back down when you return is generally less than the cost of maintaining temperature while the house is empty.

What’s the Best Aircon Temperature for Winter?

The flip side of efficient summer cooling is efficient winter heating, and this is where many Australians leave money on the table by either overheating the house or defaulting to expensive electric resistance heaters when they already have a perfectly good reverse cycle system on the wall.

The best temperature for an air conditioner in winter (heating mode) is around 18°C to 23°C. These ranges deliver both comfort and energy efficiency, and are particularly suited to Australia’s climate, where winters are generally milder than in many Western countries.

To balance warmth, efficiency and performance, 18–21°C in heating mode is a good temperature for your aircon in winter. For cost and energy savings, changing the unit’s temperature to a lower setting will help reduce electricity consumption, for example, instead of setting your system to 24°C, lower your heat set point to 21°C. The lower the set temperature, the less energy your air conditioner will use. 

The same 10% per degree rule applies in reverse in winter, every extra degree you add to your heating set point costs approximately 10% more to run.

A practical winter guide:

One thing Australians often get wrong in winter: setting the heater to 24°C or 25°C because that’s the same temperature they use in cooling mode. In heating mode, that’s much warmer than necessary and costs significantly more to run. Rug up with a jumper and set it to 20°C instead, the savings across a three-month winter period can be well over $100 for a typical household.

How to Reduce Your Air Conditioner Electricity Costs

Getting the temperature setting right is the single biggest lever, but there are plenty of other things you can do to keep bills down without compromising comfort.

1. Don’t Fight the Climate, Work With It

Before you reach for the remote, try to reduce how much heat your home is absorbing in the first place. Heat can come in through walls, windows, ceilings and under doors. Closing blinds and windows before it starts getting hot, using draft stoppers on external doors, and installing external shading on north and west-facing aspects of the house can all reduce the load on your air conditioning system. 

Insulation is far more important than many people realise. Adding insulation to your ceiling alone can reduce heat by up to 35%, which will make a real difference to your energy bill at the end of summer. 

2. Use Fans Together With Your Air Conditioner

Using ceiling fans along with air conditioning can make things feel cooler by 2–3°C due to air movement, meaning you can set your air conditioning at a higher temperature. Fans use minimal power compared to air conditioning.

A 2022 study found that using a fan as your first choice for cooling can save about 75% of the energy costs compared to going straight to the air conditioner, and can increase the upper temperature threshold at which air conditioning needs to be turned on by around 3–4°C. 

3. Only Cool (or Heat) the Rooms You’re Using

Close doors between conditioned and unconditioned areas. If you have a ducted system, use the zoning features to only run it in occupied rooms. If you have ducted air conditioning or more than one unit, use zoned heating and cooling so it’s only operating in areas people are actually using. 

4. Use the Eco or Economy Mode

Economy Mode slightly alters the target temperature, typically by a single degree, which reduces the load on the compressor and lowers energy consumption. Even though this adjustment seems minimal, over time it can lead to significant energy savings. Most modern split systems from brands like Fujitsu, Daikin, Mitsubishi Electric, and Panasonic have this feature, check your remote or manual.

5. Use Timers Smartly

Scheduling timers earlier in the day when both indoor and outdoor temperatures are lower enables your air conditioner to achieve the desired temperature with less strain and lower energy consumption. Switching your AC on during the hottest part of the afternoon forces the unit to work much harder and longer to cool your space. 

On a hot day, pre-cool the house in the morning before temperatures peak outside, rather than waiting until mid-afternoon when your system has to battle maximum heat.

6. Keep Your Unit Maintained

A dirty air conditioner works harder, costs more to run, and breaks down more often. Blocked filters reduce airflow and force the system to compensate with higher energy use. Make sure your unit is regularly maintained and the filter kept clean so it can work as efficiently as possible. 

Cleaning the filters is a simple DIY task most people can do themselves. Our step-by-step guide on how to clean your air conditioner walks through the whole process, filters, indoor unit, and outdoor unit, including what to leave to a professional and when to book a service.

7. Check the Outdoor Unit’s Position

To maximise efficiency, place the outdoor unit in as cool a place as possible, ideally on a southern wall, or a well-ventilated, shaded area. An outdoor unit in full sun will struggle to expel heat and will run less efficiently than one that’s protected from direct sunlight. 

If your outdoor unit is baking in the afternoon sun against a west-facing wall, it’s costing you more to run than it should. A shade structure or strategic planting (keeping at least 600mm clearance around the unit) can help.

8. Use Wi-Fi and Smart Features

Invest in a smart air conditioner with app capability so you can switch it on remotely to cool down the house before you get home, or switch it off if you forgot when you left. Several brands also offer energy monitoring through their apps, so you can track usage in real time and adjust habits accordingly.

9. Consider Your Energy Star Rating

When it’s time to replace your system, the star rating on the label matters enormously. Look at the unit’s energy star rating, or the running costs calculated in independent testing, these give you the best idea of which models are the most cost-effective to run. A higher-star model costs more upfront but will pay for itself in electricity savings over its lifespan.

The Zoned Energy Rating Label (ZERL), now required on new split systems sold in Australia, provides seasonal efficiency ratings across three climate zones (hot, average, and cold). This is more useful than the old single-number star rating because it reflects how the unit actually performs in your region’s conditions.

10. Don’t Size Up “Just to Be Safe”

Getting the right size unit for your space is critical to efficiency. If the air conditioner is too big for the room, it may run frequent short cycles which can mean the room gets too hot or cold, the air isn’t dehumidified enough, and both power usage and running costs increase. If it’s too small, it runs at maximum output more often, drying the air out and increasing wear and running costs. 

If you’re not sure what size system your space actually needs, our guide on how to size your air conditioner correctly walks through how to calculate the right kW rating for each room, taking into account ceiling height, insulation, window orientation, and local climate.

Air Conditioning Temperature Settings on the Central Coast, Tuggerah, and Surrounds

If you’re on the NSW Central Coast, whether you’re in Tuggerah, Wyong, Warnervale, The Entrance, Berkeley Vale, Charmhaven, Terrigal, Gosford, or anywhere in between, your climate presents a specific set of considerations that affect how you should set and use your air conditioning.

The Central Coast sits in a temperate coastal zone where summer temperatures regularly reach the mid-to-high 30s, and the humidity during January and February can make 29°C feel significantly worse than the thermometer suggests. That humidity factor is important: on a muggy day, simply dropping your thermostat from 25°C to 22°C may not actually make you feel more comfortable if the humidity is the real problem. Before reaching for a lower temperature setting, try switching your system to Dry mode for 20–30 minutes to pull moisture from the air first, you’ll often find that 24°C–25°C in Cool mode afterwards feels perfectly comfortable.

Winter on the Central Coast is mild compared to inland NSW, but the morning and evening chill, particularly in elevated pockets of the region, is real enough to warrant running your system in heating mode on most days from June through August. The good news is that because outdoor temperatures rarely drop below 5°C–8°C, your reverse cycle system operates at its most efficient in these conditions. Setting your system to 20°C–21°C for heating on the Central Coast is usually all that’s needed, there’s rarely a need to push above 22°C unless you have an older, poorly insulated home.

For newer residential estates in Wadalba, Hamlyn Terrace, and the Warnervale corridor, which tend to feature better insulation and double-glazed windows than older stock, you can often maintain comfort at slightly higher set points in summer and lower set points in winter than you might in an older home, directly reducing your running costs. Coastal properties in The Entrance, Bateau Bay, and Toowoon Bay should also pay attention to keeping outdoor condenser units clean and well-maintained, as the salt air accelerates corrosion on the fins and housing. A professional service every 12 months is particularly important for properties within a few kilometres of the coast.

Tech Air Solutions services the full Central Coast corridor, from Gosford in the south to Wyong, Tuggerah, and Warnervale in the north. If your system isn’t running efficiently, isn’t reaching your set temperature, or your power bills seem disproportionately high relative to your usage, it may be time for a professional service or an assessment of whether your current unit is appropriately sized for your space.

Conclusion

The single most impactful thing you can do to reduce your air conditioning costs in Australia is also the simplest: set your thermostat to 25°C–26°C in summer and 20°C–21°C in winter, and leave the system to do its job. Each 1°C increase of the thermostat setting in summer will save about 10% on your energy usage, so even a 2–3°C adjustment from what many people default to can deliver a meaningful reduction in bills over an entire season.

Pair a sensible temperature setting with a clean, well-maintained unit, good use of fans and timers, and a home that’s as well-sealed and shaded as you can manage, and you’ll have a comfortable home through every season without unnecessary bill shock.

If you’re not sure whether your current system is running as efficiently as it should be, or if you’re planning a new installation on the Central Coast, get in touch with the team at Tech Air Solutions for an obligation-free assessment.

Frequently Asked Questions