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How to buy a great air conditioner

Choose one that suits your home and saves you money.

woman holding remote in front of air conditioner

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 conditioner buying guide, and our portable air conditioner buying guide.


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Which type of air conditioner you should get

For most homes, a reverse-cycle split-system air conditioner will be the best option. Let's break down what that means.


These have two parts: an indoor unit and an outdoor unit, connected by pipes containing refrigerant gas. They're the most common air conditioner type in Australia, and are good for a room or open plan area up to about 60m2

Price range: $600–5500.


Similar to a split-system, but with one outdoor unit connected to two or more indoor units. Good for two or three rooms that are reasonably close together, especially when separate split-systems or a ducted system aren't suitable. 

Price range: About the same as the equivalent separate split-systems ($600–5500 per system). 


These have a discreet central unit, usually located out of sight in your roof, connected by air ducts to air outlets and sensors in each room. Good for cooling and heating a whole house. See our ducted air conditioner buying guide for more details. 

Price range: $5000+ (can easily be $10,000 or more).


A single box unit, installed in a window or through an external wall. Good for rooms and open-plan areas of up to 50m2. Smaller units can be plugged into a normal power point; larger ones may need additional wiring. Not quite as efficient or effective as split-systems but a reasonable budget option if a split-system isn't an option (for example if you're renting). 

Price range: $500–1100.


A single unit that 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. Good for rooms in households when a built-in option isn't feasible (such as if you're renting). Not as efficient as split-systems. See our portable air conditioner reviews

Price range: $300–1100.

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 under $1500.

Reverse-cycle vs cooling only

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. 

Most cooling-only and reverse-cycle models aren't very different for cooling efficiency, but the models that score best in our test for cooling efficiency all happen to be reverse-cycle models. Perhaps because reverse-cycle is the most popular type of air conditioner, the market for them is more competitive and it may be that manufacturers invest more in developing efficient reverse-cycle models.

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. 

But even if you only use heating occasionally, you're better off getting a reverse-cycle model in most cases. 

How reverse-cycle works

In cooling mode, a reverse-cycle split-system air conditioner extracts heat from the indoor air and moves it outside, via the refrigerant gas in the pipes connecting the indoor and outdoor units. The outdoor unit releases the heat and pumps the cooled refrigerant back to the indoor unit where the cycle continues. In heating mode, the process is simply reversed, to extract heat energy from the outdoor air and send it indoors (yes, even in cold weather there's some heat energy in the outdoor air).

What size air conditioner you need

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

Read the full article 'What size air conditioner do I need?'. 

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 that are 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 consumption 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

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 conditioner 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.

The cooling load and heating load calculators on, by the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH), are worth using – they let you factor in a lot of details about the room, its insulation, window orientation and more to get an accurate guide to the right air conditioner size. also has a size calculator you can try. Alternatively you can try the calculators on manufacturer and installer websites, but we think these tend to overestimate the capacity you need.

Star rating labels

Residential split-system air conditioners have to meet minimum energy performance standards (MEPS) to be sold in Australia. This means you can be assured that any new model you buy will be reasonably energy-efficient.

When a manufacturer registers a model with the government Energy Rating system, the air conditioner gets a star rating label for cooling and heating based on its test results against the Australian standard for air conditioners. You'll see the label on the model in store or online. This gives a quick and easy way to compare models. 

The more stars, the more efficient the model and the less it should cost to run, assuming it's been correctly installed. 

Even a model with one or two stars is still OK, but a model with five or six stars (or more) is clearly better, though the more efficient model might also be more expensive.

The new rating according to where you live

The old star rating label had one rating for cooling and one for heating. Any new model registered from April 2020 onwards has a new star rating label, known as the Zoned Energy Rating Label (ZERL). This shows three cooling star ratings and three heating star ratings, based on the climate zone where the unit is installed. 

An air conditioner that's good at cooling a home in an average climate zone (see below) might not be the best choice for someone living in a hot zone, for example. Likewise, others might be best suited to heating homes in cold zones. These zone ratings help you choose the best model for your area and your needs.

The three climate zones are:

  • Hot: northern Australia including Darwin and Brisbane
  • Average: the middle zone of Australia including Sydney, Adelaide and Perth
  • Cold: southern Australia including Melbourne, southern WA, Canberra and eastern state mountain regions, and Tasmania. It also includes New Zealand.

Our review includes the zone star rating labels for each model where available. There are still many older models on the market without this data; once all models are registered to the zoned ratings, we'll look at providing scores based on this information.

Zoned air conditioner energy rating label

The Zoned Energy Rating Label for air conditioners (image supplied by Department of Industry, Science, Energy and Resources).

Cost to run an air conditioner

Running costs for a medium-sized air conditioner ranges from around $400–550 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 Approximate yearly cost to run*
Small (up to 4kW) $310–490
Medium (4–6kW) $390–550
Large (over 6kW) $420–600
* 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.

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, cooling the room.
  • Heat: Pumps heat from the outside to the inside, warming the room.
  • 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, while others need a controller device added to the air conditioner to enable it.

Remote control

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

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 to where it's needed.

Restart delay

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


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, so consider outdoor unit placement carefully.

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.

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.

Demand Response Enabling Device (DRED)

  • If you have an air conditioner with the Demand Response Enabling Device (DRED, or 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 with remote control

Most air con models can operate in temperatures from about -10°C up to about 45°C or more, which is sufficient for most parts of Australia.

Air purification

All air conditioners have a dust filter in the indoor unit. This traps dust from the air as it circulates through, mainly to stop it clogging up the internal workings. But the dust filter will only have a minimal effect, if any, on smoke and other very fine particles.

To filter out smoke, you really need a HEPA filter. But HEPA filters can't practically be fitted to split-system or ducted air conditioners, because air conditioners have to deliver quite significant volumes of air flow into the room, and would need massively powerful fans in the indoor unit to force that amount of air through the very tight weave of a HEPA filter.

However, many new air conditioner models do have an air purification feature, typically based on ionisation or photocatalytic filters, This is not likely to be as effective as the HEPA filter that you'd find in a dedicated air purifier, but could still be useful in removing some dust, smoke, mould spores and even viruses and bacteria from your indoor air.

Our guide to air conditioner air purifier filters explains the details of how these filters work.

Online, you may find various aftermarket air purifying filters for air conditioners, described as electrostatic, activated carbon or similar. They claim to be compatible with major air conditioner brands and in some cases can be cut to size to suit different models. 

Be cautious with any such filters. While they may provide filtration as claimed, it's highly unlikely that they've been thoroughly tested with every air conditioner brand, and using non-genuine parts may reduce your air conditioner's performance, possibly cause damage and could void your warranty.

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.


  • 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 (meaning you'll need to purchase the unit yourself). To find out more, read our article How much does an air conditioner cost to install or replace?
  • As well as an ARCtick accreditation, your air conditioner installer should have an electrical qualification in order to wire your air conditioner into your home. Many don't, but this means they will be unable to offer a warranty on the electrical work, only the air conditioner itself. Likewise, plumbing your air conditioners' drain into your home's stormwater system needs to be performed by a qualified plumber. So check that the installer you choose has the necessary accreditations to carry out the whole installation.
  • It's generally better to install an air conditioner on a longer wall of a room, and not directly above a window, 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.
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.

  • 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.
  • Once you've got your air conditioner, don't forget to clean the filters periodically and have the unit serviced regularly.

Stock images: Getty unless otherwise stated.