5 expert tips on how to set your air con & avoid bill shock in summer

Our air conditioners work overtime to keep our homes comfortable during the Aussie summer, but if we’re not careful this can lead to bill shock. But fret not, there are things you can do to keep your AC costs down while still keeping cool. Canstar Blue has gone straight to the source to unearth some pro tips from National Product Manager at Mitsubishi Electric Australia, Atesh Mani, on how to set your air con & avoid bill shock in summer.

1.     Know how to set your air conditioner in summer

According to Atesh, the ideal room temperature to set your air conditioner to is 22°C or 23°C, which most people should find comfortable enough. Setting the room temperature to 24-25°C will reduce your power consumption even further, but it’s up to each individual to see if they find this temperature comfortable enough. The general consensus here is that every degree cooler in summer adds around 10% to your air con energy consumption.

“Heat naturally flows from a hot body to a cold body. It’s the same for room spaces. Heat from a hot room will move to cooler, air-conditioned spaces. Closing doors to unused warmer rooms will also reduce the load on your AC system,” says Atesh.

2.     Clean your air conditioner

Cleaning the filters of your air conditioner is the single most important piece of maintenance you can do to keep it running optimally. Clogged or dirty filters block normal airflow and reduce a system’s efficiency significantly, according to Atesh. The general rule here is that if you’re using your air con frequently, you should clean the filters of the indoor unit every two weeks.

  • How to clean your split-system air conditioner: Most split-system air cons will let you remove the filters for cleaning. Follow the instructions in your user manual on how to clean them. Usually, you’ll need to vacuum the surface dust and fluff first, then clean the filters with water and a mild detergent and leave them out in the sun to dry. Again, check with your manufacturer for detailed instructions.
  • How to clean your ducted air conditioner: Ducted air cons have a filter at the return air vent. This should be removed for cleaning periodically too. As a minimum, you should vacuum the surface dust and fluff to maximise airflow. For a more thorough clean, you can contact your manufacturer who can advise you on how to service your unit properly.

How to clean your air con

3.     Know when to turn your air con on and off

According to Atesh, you can save energy by turning your air conditioner on in the morning when you know it’s going to be a hot day. Your AC system will keep your living space relatively cool throughout the day, so that you don’t have to have the air conditioner running at maximum capacity when you get home, which is often during peak electricity times. This is generally between 4pm and 8pm on weekdays. Instead, if you have a newer inverter unit, it will ramp up and down during the day to maintain temperature.

Wi-Fi control with remote access to your air con is also ideal for turning your unit on before you get home. If you know it’s going to be a hot day, you can use the schedule functions in your controller or Wi-Fi control to turn the system on early in the day to pre-cool the house before it gets a chance to warm up. Homeowners with solar power can also utilise their power generation during the day to offset the power consumption of their air conditioner.

4.     Find out which air con is most energy-efficient for you

Your first consideration when buying an air conditioner is to select the right unit size for your home or room. You’ll need an AC unit with enough power to cool your living space adequately without working too hard or guzzling energy for nothing. Secondly, it’s important to compare air conditioners on their energy efficiency star rating. All air con units sold in Australia must display a Zoned Energy Rating Label (ZERL). This will tell you:

  • how efficient an air conditioner is, depending on where you live
  • how much cooling and heating it can provide
  • how much electricity it uses
  • how loud it is

Window/wall air conditioners. A window or wall air conditioner looks like a box, and is installed either through a semi-opened window or through a hole in the wall. This type of air conditioner is only suited to cool single rooms, rather than an entire house. This is the cheapest option to buy, but also the least energy-efficient of all types. Window or wall units are also noisy and often lack modern features compared to newer split-systems and ducted air conditioning units.

Split-system air conditioning units. Split-system air conditioners come in two parts: the indoor unit, which is usually mounted up high on a wall, and the outdoor unit, which is usually installed on the outside wall, usually at ground level. These types of air conditioners can only cool one room (similar to a window unit), such as a bedroom or lounge room. The capacity of the units, measured in kilowatts (kW), determines how much space you can effectively air condition. Split-system air conditioners are generally the most energy-efficient type of air con, but can be more expensive to buy if you’re wanting to cool an entire house, as each room will need its own separate unit.

Ducted air conditioning units. Just like split-systems, ducted air conditioners come in two parts. The indoor unit however, sits up inside the roof space and blows cool (or heated) air through ductwork to all of the rooms where the ducts are installed. Ducted air conditioning provides a cooling solution for the whole home. The main benefit of ducted units is zone control, which allows you to only condition certain sections of your home at a time. You can shut off areas that are not being used and direct the air conditioning to where you want.

How to save on air con bill in summer

5.     Know which kilowatt size to buy

The kW capacity required for an air conditioning system to run at peak performance will be dependent on a number of factors, such as the technology being used, your climate zone, building materials and orientation, how many people live in your house, the quality of insulation and so on.

Atesh says rooms with lots of glass, north-facing windows or lack of insulation will require a higher capacity unit. To choose the right air con size for your home, it’s best to consult an air con specialist who can talk you through all of these factors in more detail and calculate a ‘heat load’ in kW to match you with a system.

“Larger kW air conditioning units will cost more to run than smaller units. However, choosing the correct size unit is critical to ensure the unit runs at its peak performance. A unit that is too small will be forced to run at maximum capacity all of the time, potentially using more energy than what’s required,” says Atesh.

“A unit that’s too big will reach the set temperature and turn off more frequently which is not good for the health of the unit. A system that is the correct capacity and is an inverter type will only use the required energy and ramp up and down as required.”

Here is a general air con size guide for your reference:

Room size Air con kW capacity
10-25 square metres 2.5kW
25-35 square metres 3.5kW
35-60 square metres 5-6kW
60-80 square metres 7-8kW

General guide only

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Picture credits: Fizkes, Shutterstock.com/Andrey_Popov, Shutterstock.com/Wstockstudio, Shutterstock.com.

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