We're well into summer, and the air conditionings are blasting nationwide after what has been the fourth-warmest December on record.

Many may have heard the spiel of the “18-21ºC” range being the best or most efficient. But this is not entirely true. In fact, the most energy efficient temperature ranges are entirely in the 20's range. Turns out, every degree increase in temperature can save up to 10% on energy usage. 

Image: Know the most efficient temperature setting for your air conditioning this summer. Doing so could help you save on your electricity bills and ease pressure on your air conditioning system. 

The climate is a large factor in determining the most efficient temperature for your air con. Australia is split into many differing climate zones, shown in the map.  

Figure: Map detailing the most comfortable energy-efficient temperatures to run your air conditioner over summer based on Köppen climate zones (Bureau of Meteorology, 2005).

Starting in the tropics, it's important to have an efficient setting to regulate the oppressive summertime humidity, since the air conditioner will likely be running most of the time. To rest easy, a temperature setting of 22-25ºC is the most efficient range.  

Across most of central Australia, the arid to semi-arid climates, characterised by harsh, dry and often dusty summers mean filters must be checked regularly. In these areas, the most efficient temperature setting is between 21-23ºC. 

Moving to subtropical parts of southeast Queensland and elevated New South Wales, the most efficient temperature setting is between 24-25ºC. These areas can still receive muggy and humid summers, so whilst this range might be surprisingly high, it means the system will not have to work as hard to maintain a comfortable temperature. 

Oceanic climates of the southeast corner can have some of the most varied weather conditions in summer, being both elevated and inland. In these areas, the most efficient temperature setting is between 26-27ºC. Parts of southern Victoria may experience heatwave conditions, so in these instances, 23-24ºC is efficient but also comfortable.  

Finally, for Mediterranean climates along the Bight and southwest coasts, drier summers mean humidity is nowhere near as oppressive. Summertime air conditioning is most efficient when the dial is between 23-24ºC.  

These temperatures serve only as rough guides, and are dependent on your level of comfort, as well as short-term variations during the season. Remember to stay cool and hydrated for the summer!