The ideal AC temperature in Celsius for comfort and energy efficiency is generally 24-26°C in summer, while for winter heating, 18-20°C is recommended, though personal comfort varies, with 21°C often cited as a good middle ground. Setting it too low (e.g., 18°C in summer) wastes significant energy and doesn't cool faster.
On average, the best air conditioner temperature setting for summer in Australia is around 23℃ – 24℃ for comfort or 25℃ – 27℃ for maximum energy savings. In winter, reverse cycle heating should be set to around 18℃ – 20℃. However, the perfect setting will depend on your state and region.
The 3-minute rule is a simple but important guideline: wait at least three minutes after turning your air conditioner off before turning it back on. That short pause gives the refrigerant pressure in the system time to equalize.
According to most professionals, the ideal temp for ac is between 22 and 26 degrees Celsius. Most people find this is the ideal air conditioner temperature range. 25.5 degrees Celsius is a low enough temperature for you to function comfortably but also high enough so your AC doesn't run all the time.
The recommended air conditioning temperature is generally between 25-27°C for cooling and 18–21°C for heating. These ranges keep your home comfortable while ensuring your system runs efficiently without unnecessary energy use.
The sweet spot for indoor temperature is typically around 20-22 degrees Celsius (68-72 degrees Fahrenheit). This range promotes better sleep, aids concentration, and supports overall physical comfort. Straying too far from this range may lead to health issues.
Setting your air conditioner to 25°C (77°F) is more energy-efficient than lowering it to 18–20°C. According to the Bureau of Energy Efficiency, maintaining the AC temperature between 24°C and 26°C strikes the best balance between comfort and energy conservation.
The WHO recommends 18C as a minimum for indoor temperature but recommends 21C if there are any children or elderly people in the home. Overall, the range of temperatures they deem safe is 18C to 22C, but we'll stick with the 21C.
According to the U.S. Department of Energy, the best AC temperature for saving energy is 75–78°F (25.5°C) when you're at home and need cooling. Increase the temperature by about 7°F when no one is home to significantly reduce energy consumption.
Take these steps to increase the efficiency of your heating and cooling system.
How cool should my house be if it's 100 outside? Your AC can typically cool about 20°F below the outdoor temperature, so if it's 100°F outside, maintaining 78–80°F indoors is reasonable.
The "AC 5000 rule" (or $5,000 rule) is a common HVAC guideline: multiply your air conditioner's age (in years) by the repair cost; if the total exceeds $5,000, replacing the unit is generally more cost-effective than repairing it. This rule helps homeowners decide if it's better to invest in a new, more efficient system versus sinking money into an aging one, but it's a guideline, not a strict law, with other factors like energy efficiency and warranty also influencing the decision.
Determining the right hours per day your AC should run is crucial for maintaining comfort without incurring unnecessary costs. On an average summer day, a general guideline is that your AC should operate between 12 and 16 hours.
Keep your air conditioner in a cool place.
A unit operating in the shade uses 10 percent less electricity than when it's in direct sunlight. Provide shade for your aircon but be sure not to block the airflow. Don't place lamps, televisions, and other items which can be a source of heat near your unit.
According to The Sleep Charity, the ideal bedroom temperature for sleeping is 16–18°C. Anything over 24°C could be too hot and make you restless, while trying to sleep in a cold room with a temperature below 12°C could make it harder to nod off.
For Australia, the ideal sleeping temperature is generally cool, between 15°C and 20°C (59-68°F), with some experts suggesting 17-19°C for deeper sleep, as a cooler environment helps your body's core temperature drop, facilitating better rest, though personal comfort varies. Temperatures above 24°C can disrupt sleep cycles, so using air conditioning, fans, or good ventilation helps, especially in warmer Australian climates, to keep the room cool enough for quality sleep.
Even if you prefer leaving your air conditioner running when you're home, we recommend turning your system off anytime you leave the house for more than an hour or two. This practice can lower your energy bill and save you money in other ways.
Many people assume that starting up an AC system requires a huge burst of power, but the energy used during startup is minor. AC units draw a slightly higher amount of power for a few seconds when turning on, but this is not enough to outweigh the energy saved by shutting the system off for hours at a time.
The 3-minute rule states that one must wait for 3 minutes before turning on the air conditioning again. The reason? It balances the system's pressure and safeguards the compressor from damage. The pause is necessary for the condensate and refrigerant to start fresh.
Humidity Plays a Big Role
Humidity affects how we perceive temperature: Summer air is more humid, which helps trap heat against your skin, making 73°F feel warmer. Winter air is drier, pulling moisture (and warmth) from your skin, making 73°F feel noticeably colder.
Yes, -23 is cooler than -15.
No, leaving the AC on all day is generally not cheaper in Australia; it's usually more efficient to use it intermittently or strategically, turning it off when you're out and using timers/thermostats for smart cooling, though pre-cooling on very hot days with solar panels can be a good tactic. The main goal is to maintain a comfortable temperature rather than constantly fighting extreme heat, as running it non-stop uses significantly more energy and can be expensive.
Our ideal body temperature for sleep is 18 to 19 degrees Celsius. Every degree above that makes it harder to sleep – and anything over 25 degrees can make for a very uncomfortable night.
Setting it to 24°C significantly reduces the workload on your unit, leading to substantial energy savings. Studies suggest that raising the temperature by just 1°C can result in a 6% decrease in energy consumption. Lower electricity bills: By using less energy, your AC translates to lower electricity bills.