What are the energy costs of running an air conditioner?

Energy efficiency labelling

Almost all household appliances now come labelled with a universal star rating system so you can quickly and easily determine which products are more efficient than others. The ratings usually go on a scale from 1 to 6 and on reverse-cycle air conditioners (those that can heat as well as cool) you will get a blue star rating for cooling, and a red star rating for heating.

Energy Rating Label (ERLs) are a collaborative initiative called the Equipment Energy Efficiency Program (E3) involving representatives drawn from all jurisdictions in Australia and New Zealand. ERLs give you an easy way to compare efficiency to price at a glance, and to judge which individual units are right for you in the huge range of available appliances.

You can work it out yourself

Perhaps you're looking for a more exact and detailed measurement of the on-going energy costs of your already installed air conditioner, especially if you have a very strict budget. it is possible to work out just how much power your air conditioning system is using by following these steps:

Step 1

Find out what your air conditioner's "input power" is. This will usually be in watts (W) or kilowatts (kW) and will be displayed on the unit itself.

Step 2

Take a look at your energy bill. There should be an "energy tariff rate". This is the amount you pay per unit of electricity, and is usually measured per kW – so if the input power is in watts, you will need to convert to kW (by simply dividing the number by 1000). If you are unsure what your energy tariff rate is, use 30 cents per kW for a rough estimate.

Step 3

Multiply the input power by the energy tariff. You now have an hourly energy cost.

Step 4

Figure out how many hours per day you think you will use the air conditioner. Multiply this by the hourly running cost and you have a daily energy cost.

6 tips for saving on energy costs

It can be daunting to look at the costs for installing and running air conditioning, and you might think you can't afford it. However, before you decide that you'll just have to live in the heat - consider these tips for saving on your air conditioning energy costs:

Set your air conditioner to 25 degrees Celsius. Air conditioners run most efficiently at this temperature and it is the most comfortable indoor temperature for the summer. If you drop below this temperature, you are adding significantly to your costs.

Where possible, don't use the air conditioner and use natural airflow instead. Opening windows and doors on either ends of your house can create cross-breezes to cool the whole house. When the heat is a bit more bearable, you can use this and save air conditioner use for when you really need it.

When you do have the air conditioner running, make sure you close all windows and doors and also curtains and blinds. These prevent heat entering your home, keeping your air conditioner unit running more efficiently.

Cleaning the filter of your air conditioner regularly ensures that it runs efficiently.

Make sure your walls and ceiling are well insulated to so that heat doesn’t get in making your air conditioning work any harder than it should.

Whenever you leave the house, turn off the air conditioner. Leaving it on wastes energy unnecessarily.

Remember to make sure you choose a suitable air conditioning type and size for the space and climate where you are using it in order to maximise efficiency and reduce your energy costs.