KEY POINTS
- The most energy-efficient air conditioning temperature for cooling in summer is between 22–24℃, and 19–21°C for heating in winter.
- The optimal air conditioning temperature for sleeping is 18°C for adults and slightly higher for infants.
- Every extra degree of cooling typically increases your air conditioner’s energy consumption by 5–10%.
On this page:
- Best air conditioner temperature to save energy?
- Best air conditioner temperature for sleeping?
- How do temperature settings affect air conditioner costs?
- Annual cost of air conditioner cooling temperature settings
- Annual cost of air conditioner heating temperature settings
- What is the right-sized air conditioner for your home?
- Other ways to save on air conditioner usage costs
- Compare cheap electricity deals
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Best air conditioner temperature to save energy?
Depending on your state and region, the best temperature to set your air conditioner for energy efficiency is typically as follows:
- Summer: 22-24 ℃ for cooling
- Winter: 19-21℃ for heating
In reality, the optimal temperature for air conditioners will vary based on:
- The type of air conditioner: Common types of air-conditioning units include split, ducted or portable air-conditioning systems, each with their own unique set of pros and cons.
- Its energy efficiency or star rating: Energy star ratings indicate if an air conditioner is energy-efficient on a six or 10-star scale, with 10 being the most efficient.
- The type of climate you live in: In summer, if you live in the sub-tropical climate of North QLD or the NT, setting your aircon to 22–25°C will help reduce your energy usage costs. In winter, homes in Central Australia can set their air conditioner as low as 17°C, while households in Southern VIC and TAS can aim for 20–21°C in winter.
- Your comfort: Depending on your tolerance towards the summer heat and winter chills, your threshold may fall outside the recommended temperature ranges. Therefore, it is important to find a compromise between your personal comfort and energy savings.
Best air conditioner temperature for sleeping?
While this topic is subject to personal preferences, Simply Air suggests an optimal sleeping temperature of around 18°C for adults and slightly higher for babies.
However, an 18°C sleeping temperature is far below the recommended energy-efficient temperatures for either summer or winter.
Passive ways to maintain a good sleeping temperature are to look for light, breathable nightwear and bedding during summer, and warmer blankets and pajamas in winter.
Optimising bedwear and bed linens for different seasons will contribute to a more comfortable sleep without having to dial up/down the air conditioning.
Applying some of the advice in this article will help save you time and guide you towards reducing your power bill without sacrificing quality sleep and comfort.
If undisturbed sleep is your utmost priority, we suggest starting with the recommended energy-saving temperatures, slowly adjusting the temperature up or down to your liking.
How do temperature settings affect air conditioner costs?
According to the Department of Climate Change, Energy, the Environment and Water, every extra degree of heating and cooling will increase your energy consumption by 5–10%.
Energy bills will increase when the temperature of your air conditioner is set too low during summer and too high in winter.
This is because the harder the air conditioner has to work, the more electricity it will consume, which can sometimes lead to bill shock.
Using the Ergon air conditioner cost calculator, you can see how small changes to the cooling temperature you set your air conditioner can make a considerable difference to its cost.
Annual cost of air conditioner cooling temperature settings
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| Cooling capacity | 21° | 22° | 23° | 24° |
| 2.5kW | $65.44 | $59.87 | $52.91 | $48.73 |
| 3.5kW | $109.44 | $100.12 | $88.48 | $81.49 |
| 5.0kW | $170.36 | $155.86 | $137.74 | $126.86 |
| 6.0kW | $209.85 | $191.99 | $169.66 | $156.27 |
| 7.1kW | $245.95 | $225.02 | $198.85 | $183.15 |
| 8.0kW | $279.79 | $255.98 | $226.22 | $208.36 |
| 10kW | $366.67 | $335.46 | $296.45. | $273.05 |
| 14kW | $564.10 | $516.09 | $456.08 | $420.08 |
Source: Ergon Energy Air Conditioning Calculator – 16/07/2025. Assumes 34.069c/kWh electricity usage rate (Tariff 11 – Ergon Energy network) with air conditioner running four hours a day for 13 weeks of the year. General guide only.
Annual cost of air conditioner heating temperature settings
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Central heating annual costs
| Air conditioner type | Small house (100m²) | Medium house (160m²) | Large house (220m²) |
|---|---|---|---|
| Multi-split reverse-cycle 1.5 star rating | $770 | $1,232 | $1,694 |
| Multi-split reverse-cycle 2.5 star rating | $513 | $924 | $1,271 |
| Ducted reverse-cycle (unzoned) 1 star | $1,155 | $1,848 | $2,542 |
| Ducted reverse-cycle (unzoned) 2.5 star | $722 | $1,320 | $1,815 |
Source: sustainability.vic.gov.au. Calculations are based on an electricity tariff of 29.3c/kWh (peak) and 21.6c/kWh (off-peak). Approximate annual energy costs are based on an average pre-existing 2005 house in a Melbourne climate, heating to 20˚C. General guide only.
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Reverse-cycle air conditioner
| Rating | Annual energy costs | |
|---|---|---|
| Small room (12m²) | 2 stars | $98 |
| 3.5 stars | $69 | |
| Medium room (30m²) | 1.5 stars | $287 |
| 3 stars | $191 | |
| Large room (60m²) | 1.5 stars | $574 |
| 3 stars | $383 |
Source: sustainability.vic.gov.au. Calculations are based on an electricity tariff of 29.3c/kWh (peak) and 21.6c/kWh (off-peak). Approximate annual energy costs are based on an average pre-existing 2005 house in a Melbourne climate, heating to 20˚C. Genrarl guide only.
What is the right-sized air conditioner for your home?
Below is an approximate guide to ideal air conditioner capacities given the room size.
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| Room size m2 | Cooling capacity (C) / heating capacity (H) |
|---|---|
| 9m2 | 2.5kW(C)/3.2kW(H) |
| 25m2 | 3.5kW(C)/3.7KW – 4.3kW (H) |
| 30m2 | 3.5kW(C)/3.7KW(H) – 5.0kW(C)/6.0kW(H) |
| 40m2 | 5.0kW(C)/6.0kW(H) – 6.0kW(C)/7.2kW(H) |
| 45m2 | 6.0kW(C)/7.2kW(H) – 7.1kW(C)/8.0kW(H) |
| 50m2 | 7.1kW(C)/8.0kW(H) – 8.0kW(C)/9.0kW(H) |
| 55m2 | 8.0kW(C)/9.0kW(H) – 9.2kW(C)/10.0kW(H) |
Source: Air Conditioner Buying Guide, Harvey Norman. General guide only.
If a room is larger than the air conditioner was designed for, the unit will be less effective at controlling the temperature. Your air conditioner might be set to cool to 24°C, but the room’s temperature might actually be 28°C.
If your room is too small for the air conditioner, it will cool the room quickly before shutting off. An air conditioner that turns on and off can use more energy and potentially lead to a larger-than-necessary energy bill.
The ceiling height of the area you’re heating or cooling can also change the heating or cooling capacity of your air conditioner. The higher the ceiling, the more powerful an air conditioner you will need.
If you’re unsure about what size air conditioner you need, we recommend seeking a professional quote.
Other ways to save on air conditioner usage costs
- Sealing and insulation: If the space you’re trying to heat or cool is poorly sealed or insulated, your air conditioner will have to work harder to reach the temperature you have set (i.e. if you’re trying to cool your home down to 24°C, you may have to set your air conditioner’s temperature to 20°C)
- Energy efficiency: An air conditioner will be labelled with two separate star ratings. The blue star rating shows the air conditioner’s cooling efficiency rating, while the orange one shows heating efficiency
- Alternatives to air conditioning: In summer, ceiling fans, tower fans and pedestal fans have considerably lower running costs than air conditioners. To keep warm during winters in colder climates (e.g. Brisbane, Darwin), gas or electric heaters typically run cheaper than a reverse-cycling air-conditioner.
- Maintain your air conditioning unit/s: If you find that your home isn’t being cooled or heated properly, your air conditioner may need to be serviced. There may be coil blockages or dirty filtration, causing the unit to work harder
- Use the air conditioner’s functions:
- The timer can be utilised to ensure that the air conditioner is only being used when someone is at home
- Dehumidifier mode is handy during periods of high humidity in summer and can help remove the moisture from the air instead of just turning the temperature down. This is especially effective in subtropical climates
Compare cheap electricity deals
As the seasons change, it’s a good idea to assess your current energy plan and review the usage rates you are being charged.
Minimising usage rates will also help minimise air conditioner running costs among the running costs of other home appliances.
Regularly comparing your energy plan with the cheapest on the electricity market is a great way to avoid being charged the default market offer (DMO), which tends to be more expensive than other plans.
Canstar Blue has made it easier to compare providers by listing some of the cheapest deals in each state below.
Here are some of the cheapest published deals from the retailers on our database that include a link to the retailer’s website for further details. These are products from referral partners†. These costs are based on the Ausgrid network in Sydney but prices may vary depending on your circumstances. This comparison assumes general energy usage of 3900kWh/year for a residential customer on a single rate tariff. Please use our comparison tool for a specific comparison in your area. Our database may not cover all deals in your area. As always, check all details of any plan directly with the retailer before making a purchase decision.
Here are some of the cheapest published deals from the retailers on our database that include a link to the retailer’s website for further details. These are products from referral partners†. These costs are based on the Citipower network in Melbourne but prices may vary depending on your circumstances. This comparison assumes general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Please use our comparison tool for a specific comparison in your area. Our database may not cover all deals in your area. As always, check all details of any plan directly with the retailer before making a purchase decision.
Here are some of the cheapest published deals from the retailers on our database that include a link to the retailer’s website for further details. These are products from referral partners†. These costs are based on the Energex network in Brisbane but prices may vary depending on your circumstances. This comparison assumes general energy usage of 4600kWh/year for a residential customer on a single rate tariff. Please use our comparison tool for a specific comparison in your area. Our database may not cover all deals in your area. As always, check all details of any plan directly with the retailer before making a purchase decision.
Here are some of the cheapest published deals from the retailers on our database that include a link to the retailer’s website for further details. These are products from referral partners†. These costs are based on the SA Power network in Adelaide but prices may vary depending on your circumstances. This comparison assumes general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Please use our comparison tool for a specific comparison in your area. Our database may not cover all deals in your area. As always, check all details of any plan directly with the retailer before making a purchase decision.
Original reporting by Simon Downes
Image Source: Yuri Hoyda/Shutterstock
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