Good Temperature for Aircon: Comfort & Energy Guide

The temperature you set your air conditioner to affects both your comfort and how much it costs to run. There's no single universally correct setting — the right temperature depends on whether you're cooling or heating, the time of day, the room you're in, and your personal preference. This guide covers practical settings for different situations, and what to consider when the temperature setting alone isn't solving the problem.

1. Right Aircon Temperature

A commonly recommended range for general comfort in Australian homes is 22°C to 26°C for cooling and 18°C to 22°C for heating. These ranges are practical starting points rather than fixed rules.

The Australian government's energy efficiency guidance suggests setting cooling to 24–26°C and heating to 18–20°C as a balance between comfort and energy consumption. Each degree of adjustment — cooling lower or heating higher — increases running cost, typically by 5–10% per degree depending on the unit and conditions.

In practice, the right setting is the one that keeps the room comfortable at the lowest energy cost. Most people find 24–25°C sufficient for summer cooling in Sydney. In winter, 20–21°C is usually warm enough for a living area; some people find bedrooms comfortable at lower settings when sleeping under a doona.

2. Cooling Temperature for Summer

For summer cooling in Sydney, a setting of 24°C to 26°C is a practical starting point. The specific temperature that feels comfortable will depend on:

Outdoor temperature.

• On extreme heat days (38°C+), the system has to work harder to maintain any target temperature, and the gap between inside and outside is more noticeable.

Room sun exposure.

• A west-facing room in the afternoon gets significantly more solar heat gain than a south-facing room. You may need a slightly lower setting, or more capacity, to maintain the same comfort level.

Airflow.

• Running the fan at medium to high while cooling can improve the effective comfort level without lowering the temperature setting, because moving air feels cooler on the skin.

Number of people in the room.

• Each person adds body heat. A room with four people will feel warmer at the same temperature setting than a room with one.

Setting cooling to 23°C or below in summer significantly increases running costs without proportionally improving comfort for most people. If 24–25°C feels insufficient, it's often worth checking whether the unit is the right capacity for the room before defaulting to a lower temperature setting.

See our capacity guide if you're finding your current unit can't maintain comfortable temperatures on hot days.

3. Heating Temperature for Winter

For winter heating, a setting of 19°C to 21°C is a practical starting point for living areas. Bedrooms are often comfortable at slightly lower settings — many people sleep better at 18–19°C.

Reverse cycle air conditioners are among the most efficient heating options available in Australian homes. They don't generate heat by burning fuel or using resistive elements — they move heat from outside air into the room, which is why they can deliver 3–4 units of heat energy for every 1 unit of electricity they consume. This makes them substantially cheaper to run than portable electric heaters, oil-filled column heaters, or older panel heaters, particularly in Sydney's relatively mild winter conditions.

Some practical points for efficient winter heating:

Close doors to adjacent rooms

• you're not heating. Conditioning a smaller area is more efficient and reaches target temperature faster.

Let the unit run.

• Repeatedly turning the system on and off — or cranking the temperature to 30°C to "heat faster" — doesn't warm the room faster and uses more energy. Set a comfortable target and let the system maintain it.

Use the timer.

• Most split systems have timer functions that allow the unit to start before you get up or arrive home, so the room is already at a comfortable temperature without running the system all day.

4. Sleep Temperature and Bedrooms

Research on sleep quality consistently shows that cooler sleeping environments — typically 16°C to 19°C — support better sleep than warm ones. Core body temperature naturally drops during sleep, and a cool room assists this process.

In practice, the right bedroom temperature for sleep varies by individual, season, and bedding. A useful starting point is to set the bedroom unit to 19–20°C and adjust from there based on how you sleep.

Summer bedrooms: Running the unit through the night at 23–24°C is more efficient than running it cold. If the bedroom feels warm in the morning rather than during the night, consider whether the issue is room temperature or airflow — a ceiling fan in combination with the air conditioner can allow a higher set temperature while maintaining sleep comfort.

Winter bedrooms: Many people find they sleep comfortably at 18°C in winter under adequate bedding, and don't need to run the heating unit through the entire night. Setting a timer to turn the unit off 1–2 hours after bedtime and back on 30 minutes before waking is an efficient approach.

5. When Temperature Settings Do Not Solve the Problem

If you're finding that adjusting the temperature setting doesn't resolve a comfort issue, the problem may not be the setting — it may be the system itself or how it's configured for your space.

Common causes of temperature setting not working as expected:

• Undersized unit. A unit too small for the room will run continuously without reaching the target temperature on hot or cold days. This isn't solved by changing the setting — it requires assessing whether the unit is the right capacity.
• Dirty filters. Blocked air filters significantly reduce airflow and system efficiency. Cleaning the filter (a simple pull-out-and-rinse process on most units) is the first thing to check if performance has declined.
• Oversized unit. A unit too large for the room short-cycles — it reaches temperature quickly, turns off, and turns back on repeatedly. In cooling mode this can leave humidity higher than normal because the unit doesn't run long enough to adequately dehumidify the air.
• Air leaks in the room. Gaps around windows, doors, or ceiling penetrations allow conditioned air to escape and unconditioned air to enter. Improving room sealing can significantly improve how efficiently any aircon system maintains temperature.
• Unit servicing or refrigerant issues. If the system is running but not reaching temperature in conditions it used to handle, there may be a refrigerant or mechanical issue. For service enquiries, see our service page.

If you're uncertain whether your current system is the right size or type for your situation, request a quote or check-up.

FAQs

What is the best aircon temperature for sleep?

A room temperature of 16°C to 19°C is generally associated with better sleep quality. In practice, most people find 18–20°C comfortable for sleeping in a Sydney winter, and 22–24°C acceptable for summer nights. The most useful approach is to start with a moderate setting, assess how you sleep, and adjust. Running the unit on a timer rather than all night is both more comfortable and more energy-efficient.

Does a lower aircon temperature use more energy?

Yes. In cooling mode, a lower temperature setting requires the system to work harder and run for longer, increasing electricity consumption. As a general rule, each degree lower in cooling mode increases running cost by approximately 5–10%. The same principle applies in heating mode — each degree higher increases cost. Staying within the 22–26°C cooling range and 18–22°C heating range is the practical balance between comfort and efficiency for most Sydney homes.

What if my aircon does not reach the set temperature?

If the unit is running but not reaching the target temperature, start with the basics: check that the filter is clean, all windows and doors in the room are closed, and the set temperature is realistic for current outdoor conditions. If those are all fine and the unit consistently underperforms, it may be undersized for the room, have a refrigerant issue, or need servicing. See our capacity guide for sizing information or contact us for a service assessment.

Need a new system that actually keeps up with your home's needs? Get a fixed installation quote here.