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How to buy the best air conditioner

Choose one that suits your home and saves you money.

wall mounted air conditioner

The lowdown on air con

Choosing the best air conditioner can be a challenge. What size do you need? How much will it cost to run and how noisy will it be? We'll help you find the right model for your home.

This guide focuses on split-systems, as these are the most popular type of air conditioner in Australia. You can also check out our ducted air conditioners guide, and our portable air conditioners guide.

Looking for the best air conditioner?

See our expert product reviews.

What type of air conditioner should I get?

For most homes, a reverse-cycle split-system air conditioner will be the best option. 

Let's break down what that means.

What is a split-system air conditioner?

These have two parts: 

  • an indoor unit that blows the cool air into your home 
  • an outdoor compressor unit. 
Which type of air conditioner do I need?
How much does an air conditioner cost?
Type Suitable for cooling:
A room or an open-plan area of up to 60 square metres.

Price range: $600–$5500.
Multi-split 2 or 3 rooms (that are reasonably close together).

Separate indoor units are connected to a single outdoor unit.

About the same price range as split-system.
Ducted A large home throughout.

Ducting connects a central unit to air outlets and sensors in each room. See our ducted air conditioner buying guide for more details.

Price range: $5000+ (can easily be $10,000 or more).
Wall/window Rooms and open-plan areas of up to 50 square metres.

Usually installed in a window or external wall. Smaller units can be plugged into a normal power point; larger ones may need additional wiring. Not very common.

Price range: $400–$1100.
Portable Rooms in households that can't have split-system air-con (e.g. renters)

A single unit can be moved from room to room as needed (but generally not easily). Most have a flexible duct that must be attached to a window to vent the heat outside. Not as efficient as split-systems. See our portable air conditioner reviews.

Price range: $300–$1300.

CHOICE Tip: You don't need to pay top dollar to get the best air conditioner. Some recommended models in our air conditioner reviews cost less than $1500.

What is reverse-cycle air conditioning?

A reverse-cycle air conditioner can heat as well as cool – in fact, it's one of the cheapest ways to heat your home in winter.

If you only need an air conditioner for cooling in summer (for instance, if you live in an area with mild winters or you already have another heating system), then a cooling-only air conditioner could be right for you. They're generally cheaper than reverse-cycle models but usually have all the same features.

What size air conditioner do I need?

Here's our rough guide to the air conditioner capacity (size) you'll need for a particular room size.

Room size Capacity
Up to 20 sq m 2–2.5kW
20–40 sq m 2.5–5kW
40–60 sq m 4–6kW
60–80 sq m 5–7kW
80+ sq m 6–9kW

So, that's the ballpark guide, but you really need to do an accurate calculation before buying your air con, or else you'll run into these issues:

  • Models too powerful for the room size may run frequent short cycles to achieve the target temperature. This can result in the room getting too cold or hot, inadequate dehumidification (i.e. not drying the air enough, making the room feel less comfortable), increased power use and running costs, and wear and tear on the system.
  • Underpowered models may have to run more often at maximum output, which could dry the air too much and also create excessive wear.

CHOICE tip: Choose a model with equal or slightly greater capacity for the room.

For example, if you calculate the room needs a 6kW model, then look for an air conditioner with rated cooling capacity in the range 6kW to 6.5kW (roughly). It's probably a safer bet to get a model slightly above the required capacity than slightly below it, as a little extra grunt may help in extreme temperatures. But don't go too much above the required capacity.

How to do a proper calculation

person measuring floor space for air conditioner
A proper calculation takes all the room's details into account.

Some installers and online calculators offer only a simplistic analysis and may tend to recommend a larger capacity than you really need. 

But there are a lot of variables to consider. For example, a well-insulated room with south-facing windows will be at the bottom end of the capacity range, while an uninsulated room with west-facing windows will be towards the top. 

Likewise, a room in Perth will probably need a more powerful air con for cooling compared to an otherwise identical room in Sydney.

A proper calculation takes all the room's details into account:

  • The size of the room: length, width and height.
  • The type of room: living room, open-plan living room and kitchen, bedroom, etc.
  • The size and orientation of the windows and glass doors. A large north- or west-facing window can let in a lot of heat in summer.
  • Shading and curtains on the windows.
  • Insulation of the floor, ceiling, and walls.
  • The local climate.

Try the size calculator on by the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH). 

How much does it cost to run an air conditioner?

Running costs for a medium-sized air conditioner ranges from around $400 to $550 a year. 

We measure running costs in our air conditioner reviews. As you can see in the below table, running costs can vary by a few hundred dollars a year, depending on the model.

Running costs of air conditioners we tested
Size Yearly cost to run*
(up to 4kW)

(over 6kW)
* Based on how much each model costs to deliver a set amount of cooling and heating per year at maximum capacity, with the remainder of the year in standby mode (based on electricity costs of 30 cents/kWh). It's only indicative; your actual running costs may vary.

Heating and cooling appliances account for about 40% of the energy use in the average Australian home. Here's how to save some money:

  • Size: Having the right size of air conditioner is an important first step.
  • Star ratings: A model with more stars will be more efficient and use less power than a model with fewer stars. (Keep your eye out for a new star-rating label being phased in over the next few years that gives more information about how the air conditioner performs in different zones of Australia.)
  • Our air conditioner reviews rate each model for cooling and heating efficiency more precisely than the star ratings, and give an indicative running cost for each model.
  • Make your home as energy-efficient as possible: see our top 10 tips on keeping your home cool efficiently and effectively.
  • Use Economy mode ("Eco mode") if your air conditioner has one.
  • Set the target temperature (thermostat) to a reasonable temperature so the system doesn't have to work too hard and use more power than really necessary. 

We recommend you set your air conditioner to no more than 8°C cooler than the outside temperature. 

On a hot day – say 33°C – you might be tempted to put the air conditioner way down to 20°C, but try to cope with 25°C.

And in winter, set your reverse-cycle air conditioner to no more than 8°C warmer than the outside temperature (wear a jumper if you have to!).

Sticking to this 8°C differential will save on wear and tear on the air conditioner's motor, and save big on your energy bill. Each degree cooler (or warmer in winter) can add about 10% to the running cost.

Inverter air conditioners are generally more efficient and cost less to run than non-inverter, or conventional, air conditioners. Most split systems on the market these days are inverter models.

  • Inverter models vary the speed of the compressor (in the outdoor unit) so it speeds up or down as need demands. By not actually having to stop and start several times a day, there's less stress on the compressor and less electricity used.
  • In non-inverter models, the compressor in the outdoor unit is either on at full power, or off. This can cause more wear and tear on the compressor and uses more power to start up each time, so these models aren't as efficient to run as inverter models. They can be cheaper to buy, but you won't find many non-inverter models on the market these days.

How noisy are air conditioners?

Most modern split-system air conditioners are very quiet indoors and out, but it's worth checking an air conditioner's noise levels before you buy. 

We measure noise as part of our split-system air conditioner reviews. In our latest test, the noise from indoor units ranged from 19dB to 53dB, and from the outdoor units, 42dB to 69dB (measured on the quietest indoor fan setting).

For comparison, here are some common sound levels:

  • 30dBA: typical sound level of a quiet home
  • 50dBA: interior of a quiet car while driving
  • 60dBA: typical conversation
  • 70–80dBA: vacuum cleaner 

A noisy indoor unit may interfere with your activities, conversation or sleep. A noisy outdoor unit can disturb you (if it's too close to a bedroom or living room window) or your neighbours. 

Most local councils have noise restrictions relating to the use of air conditioners. Check council regulations before buying, and your strata rules if you live in an apartment, especially if the outdoor unit needs to be installed close to a neighbour's house.

Features to consider

Fan speeds

The fan circulates cooled or heated air around the room. Look for a model with a wide airflow range and multiple fan speeds: from very high – to help the room cool down quickly, to very low – so there's less noise and no unpleasant draught once you have the right temperature.

Operating modes

  • Auto: Automatically chooses the mode required to keep the room at the chosen temperature.
  • Cool: Pumps heat from the inside to the outside.
  • Heat: Pumps heat from the outside to the inside.
  • Dry: Dehumidifies the air. Provides some cooling, but not as much as cooling mode.
  • Fan only: Blows air without heating, cooling or drying, which is useful when all you want is a cooling breeze.
  • Economy: Also called Eco mode, this reduces power consumption. Different brands implement this in different ways. It may simply reduce the cooling or heating output by adjusting the thermostat a degree or two, or it may use sensors to detect if no one is in the room and then reduce the cooling/heating.

Human presence sensor

  • This detects whether someone is in the room, so the unit knows to keep working. Some models even direct the air movement towards the sensed person. When no one is detected, the unit might switch to an economy mode to reduce power consumption.
  • Having this feature doesn't mean you can leave the air conditioner running for hours when the house is empty. You're still much better off turning it off and using the timer function to turn it back on just before you return home, or turning it on remotely via Wi-Fi (see next item).
  • This feature goes by different names. Mitsubishi Electric calls it Absence Detection; for Mitsubishi Heavy Industries, it's Eco Operation; for Panasonic it's ECONAVI; for Daikin, it's Intelligent Eye.
person using app to control temperature with air conditioner
Many newer-model air conditioners can be controlled remotely via an app on your smartphone.

Wi-fi and apps control

  • Many newer models can connect to the wireless network in your home so you can control the air conditioner via an app on your smartphone – handy if you're at work and want to turn it on before you get home, or you're at home and you've misplaced the remote.
  • Some have this feature built in; others need a controller device added to the air conditioner to enable it.

Air filters and self-cleaning

  • Air conditioners offer increasingly sophisticated air filtration systems, to remove allergens, mould, bacteria, odours and dust from the air.
  • This is often accompanied by a self-cleaning function to keep the inside of the unit dry and reduce the build-up of dust and the growth of mould; this also helps keep the unit running more efficiently.

Remote control

Look for large, well-spaced buttons with easy-to-read labels, and a big, easy-to-read LCD screen.

wall mounted air conditioner with remote control
The remote control should be easy to read and use with well-spaced buttons.

Sleep mode

This function adjusts the temperature in steps to a comfortable level for sleeping so the air conditioner doesn't work as hard (and is quieter) when you're sleeping.

Adjustable or oscillating louvres

We recommend you point them up for cool air and down for warm. This can be done via the remote for most models. Left and right adjustability helps direct air where it's particularly needed.

Restart delay

Protects the compressor by preventing the air conditioner from starting up again too soon after being switched off.

Demand Response Enabling Device (DRED)

  • If you have an air conditioner with the Demand Response Enabling Device (DRED, also known as PeakSmart) feature, and your energy provider offers the PeakSmart service, they'll be able to remotely switch your air conditioner to an economy mode during times of high demand on the grid. 
  • This will usually have no major impact on the air conditioner's cooling (or heating) output – you might not even notice it happening – but it will reduce the amount of power the air conditioner is using, not just saving you money but also reducing the need for more 'poles and wires' to meet energy needs.
  • So far only a few energy companies provide the service. Some energy companies, including Queensland-based Energex and Ergon, also pay incentives to customers who buy DRED-enabled air conditioners.
wall mounted air conditioner illustration
A high-wall mounted air con will blow air easily across a room.

Wall-mounted or ceiling-mounted?

  • High wall: the indoor unit is mounted high on a wall so its air flow can easily blow across the room. 
  • Floor-mounted: the indoor unit is at floor level, which may be better suit some rooms. 
  • Cassette: the indoor unit is mounted in the ceiling. 
  • Floor/ceiling: can be mounted on either the ceiling or the floor.

Operating range

Do you live in a very hot or cold region? Most models can operate in temperatures from about -10°C up to about 45°C or more. This is sufficient for most parts of Australia, but check the air conditioner's operating range before you buy, to make sure it can cope with any extremes in your area. (If you live in a hot and dry climate, an evaporative cooler can be a cheaper alternative to an air conditioner.) 

Automatic de-icing

If you live in a cold area, get an air conditioner with automatic de-icing to avoid frost building up on the outdoor heat exchanger coils in winter.

Refrigerant gas

  • Ozone-depleting refrigerants such as chlorofluorocarbons (CFCs) have been essentially phased out, but the most commonly used current refrigerant gas type, hydrofluorocarbon or HFC, is also problematic. In 2016 a new international agreement was reached to phase out the use of HFCs over the next few decades.
  • We're seeing a clear trend in the models we test towards the use of R32, instead of R410A; these are both HFCs, but R32 has a lower global warming potential and should also give improved efficiency.

When's the best time to buy an air conditioner?

  • Avoid buying in peak season if you can; that will be summer in most parts of Australia, but could be mid-winter too if you're in a colder region. Installers are usually very busy in these periods and you might have to wait some weeks before your new unit can be installed.
  • If possible, shop around before the peak season starts, so that your new unit is installed and ready for when you'll need it most.
  • Alternatively, it can be worth buying just after the season ends. Old stock may be discounted as retailers make room for new models.

How to install a split-system air conditioner

split system air conditioner compressor
The compressor should be installed on a firm base or attached to a wall with sturdy brackets, and protected from direct sunlight.

  • You'll need a licensed air conditioner installer because of the gas refrigerant. Look for an installer with ARCtick approval, and get a few quotes. Most traders offer supply and install packages, and some installation only. 
  • It's generally better to install an air conditioner on a longer wall of a room, but your installer should recommend the best place for your individual situation.
  • The outdoor unit of your split-system needs to be installed on a firm base (for example, a concrete slab) or attached to a wall, using sturdy brackets. It should be as close as possible to the indoor air outlet, ideally with about three to five metres of pipes between the two units.
  • Shade the outdoor part of your air conditioner from direct sunlight – for example, by installing it on a southern wall or providing an awning.
  • Single-phase power is all you need for most single (and multi) split-system air conditioners. Three-phase power might be needed for very large multi-split or ducted systems, say 20kW capacity or more.

Last, but certainly not least, here's how to keep your air conditioner clean and well-maintained for years of efficient running.


Looking for the best air conditioner?

See our expert product reviews.

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