Australia is known to be one of the seven continents of the world. Thus, being a huge country also entails having several different climate zones that range from a tropical influenced climate to warm and dry winters, with Western Australia and Perth leaning more on the dryer subtropical or arid climate.

A long summer period of hot and dry weather makes an air conditioner a necessity in every Perth home and office. But many ask how much does it cost for a unit to run and if it is this same unit that is the power monger driving our bills right through our pockets?

## Calculating your AC running expenses

So, check on the wattage of your current air conditioning unit or the one you plan to buy so that you can calculate your total expense for a cool and comfortable place. Below is the formula for computing the cost per hour of your unit before taking in to consideration any energy efficiency of the unit.

*kW (capacity of unit) x price/ hour (based on electricity provider) =cost to run per hour (price/ kWh)*

*Price/ kWh x number of hours used in a day = daily cost*

*Daily price x 30 days = monthly cost*

Now, if we calculate the cost to run a regular use old inefficient 2.5kW air conditioner in a 25m^{2} room with a sample electricity charge of 28 cents per hour, then:

2.5kW x 28 cents/ hour = 70 c/ kWh or $ 0.7/ kWh

Daily cost (on an 8 hour usage): 560 c or $ 5.6

Monthly cost: $ 168

However, these calculations are not the real costs because air conditioners are efficient and use compressors and refrigerant gas to convert the kW to cool air a lot more efficiently. Therefore, we need to use the star rating to calculate correctly.

## How much does my air conditioner cost to run?

A 2.5 kW air condinter will cost about 22 cents an hour to run. Alternatively, a 9 kW air conditioner will cost $6.30 to run for 8 hours at full power. The table below shows you common sizes and cost associated with them.

Size (kW) | 1 hour | 8 hours |
---|---|---|

2.5 | $0.21875 | $1.75 |

3 | $0.2625 | $2.1 |

3.5 | $0.30625 | $2.45 |

4 | $0.35 | $2.8 |

5 | $0.4375 | $3.5 |

7 | $0.6125 | $4.9 |

9 | $0.7875 | $6.3 |

**Using star rating to accurately calculate running costs**

Since consumers nowadays try to look for low energy consuming products in the market, manufacturers have created ways to make their products energy efficient. This along with engineering advancements as introduced the Energy Efficiency Ratio (EER) ratings that we commonly see in today’s air conditioning units.

So, putting the EER in mind, a different accurate calculation is needed for new air conditioners today with energy star ratings:

**(KW capacity/ EER) x price/ hour = price/ kWh**

Using the previous example, if we calculate the cost to run a 2.5kW air conditioner, now with an EER of 3.21, then:

**(2.5kW/ 3.21) x 28 c/ hour = 22 c/ kWh or $ 0.22/ kWh****Daily cost (on an 8 hour usage): 176 c or $ 1.76****Monthly cost: $ 52.80**

Take note that air conditioners with EER ratings use less than half the cost of old inefficient air conditioners, therefore saving you both on expenses and from the sweltering heat of the Australian sun.

## Ways to reduce air conditioner running cost:

- Consider the wattage of your unit and its suitable cooling space. Check out our air con size guide.
- Keep the unit clean.
- Make sure that all doors and windows to the room are closed so as not to overwork the unit.
- Invest in “blackout” curtains of blinds to help retain the cold and keep out the heat.
- Use a fan to scatter the cold air of the unit.
- If possible, keep the unit’s temperature at normal levels since blistering cold levels add more to your energy consumption.

EER rated air conditioners use way lower amounts of electricity and cost less to run than regular old air conditioners. However, still a few consumers know about this. According to studies, more than half of Australian households (65%) see their air conditioners as the top culprit for high electricity bills, while only less than half (45%) are aware of EER and consider the ratings before purchasing air conditioners. So, before you get solar panels, you should know the electricity cost of your air conditioner and how to efficiently control it. In addition, The EER rating can also be helpful for calculating usage of your other home appliances.

*Note: Calculations made are indicative and is only meant to be used as a guide for calculations.*