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Air conditioner buying guide


How to choose an air conditioner to suit your home and save you money

wall mounted air conditioner

What you need to know about 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. For other types, you can also check out our ducted (whole house) system guide, and our portable air conditioner guide.

Looking for the best air conditioner?

See our expert product reviews.

Types of air conditioner

  • Split-system: These have two parts: an outdoor compressor unit and an indoor unit connected by pipes. They're usually used to cool one or more rooms, or an open-plan area, of up to 60 square metres. Price range: $600–$5500
  • Multi-split: A type of split-system, with one outdoor unit connected to two or more indoor units. This can be a good way to cool or heat two or three rooms that are reasonably close together, when separate split-systems or a ducted system aren't possible due to space limitations.
  • Ducted: The best option for temperature control throughout a large home, this consists of a central unit connected by ducts to air outlets and sensors in each room, with a control panel to set the target temperatures and the zones of the house to cool or heat. See our separate ducted air conditioner buying guide for more details. Price range: $5000+.
  • Wall/window: These models are usually installed in a window or external wall, and can cool rooms and open-plan areas of up to 50 square metres. Smaller units can be plugged into a normal power point; larger ones may require additional wiring. We don't currently include these models in our reviews, because there are fewer on the market now, as split-systems are more efficient and have become more affordable in recent years. Price range: $400–$1100.

Inverter or non-inverter?

Having decided on the general type, you also need to think about whether to go for an inverter model, and whether you want both cooling and heating, or cooling only.

  • Inverter: These models can vary the compressor speed. That means the compressor (in the outdoor unit) doesn't need to switch on and off continuously, but instead just 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 is used, so inverter models are generally more efficient and cost less to run. They can maintain a set temperature within a narrow range. Most split systems on the market these days are inverter models.
  • Non-inverter: Also called conventional air conditioners, the compressor in the outdoor unit is either on at full power, or off. The compressor switches on and off as need demands. 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, but can be cheaper to buy.  
  • Reverse-cycle: Reverse-cycle models can be used for cooling in summer and heating in winter. While the purchase and installation costs can be high compared to an electric heater, reverse-cycle air conditioners are actually among the cheapest and most effective forms of heating for large spaces over the long term. Even if you only need heating for a few days or weeks each winter, a reverse-cycle model could be your best option.
  • Cooling-only: If you only need the air conditioner for cooling in summer (for instance, if you live in an area with hot summers and mild winters, or if you already have another heating system in place), then a cooling-only air conditioner could be right for you. They're generally cheaper than reverse-cycle models and usually otherwise have all the same features.

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

Types of indoor unit

  • High wall: the most common form of split-system, with the indoor unit mounted high on a wall. This allows the air flow to easily blow across the room, and the cool air will sink down and push the hot air up and away.
  • Floor-mounted: the indoor unit is wall-mounted but at floor level — this might better suit some rooms, and could be a better option if you mainly use the unit for heating, as the hot air will come out at your level and rise to the ceiling.
  • Cassette: these have the indoor unit mounted in the ceiling. Some models can be mounted in either the ceiling or the floor.

Choosing the right capacity

Cooling and heating capacities (sizes) are rated in kilowatts (kW). A small room might require a 2.5kW model, while a large open-plan area might need 6kW or more. It's important to accurately calculate the required cooling or heating capacity of your new air conditioner. 

Some installers and online calculators offer only a simplistic analysis and may tend to recommend a larger capacity than you really need. 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 fairair.com.au by the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH). 

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.

  • Models too powerful for the room size may run frequent short cycles to achieve the target temperature – which is like tapping the accelerator in your car to maintain speed instead of applying steady pressure. 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 usage and running costs, and wear and tear on the system.
  • Underpowered models may have to run more often at maximum output, dry the air too much and you'll similarly suffer excessive wear.

Running costs

Heating and cooling appliances account for about 40% of the energy usage of the average Australian home. To save money when running your air conditioner, there are several things you can do.

  • Size: Having the correct size of air conditioner is an important first step (see Choosing the right capacity).
  • Star ratings: a model with more stars will be more efficient and use less power than a model with fewer stars.
  • CHOICE 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 thermostat (target temperature) to a reasonable temperature so the system doesn't have to work too hard and use more power than really necessary. 

Keeping a reasonable temperature

On a hot day – say 33°C – you might be tempted to put the air conditioner way down to 20°C to get the room cool as quickly as possible. But if you can cope with setting the temperature at 25°C, you'll not only save on wear and tear on the air conditioner's motor, you'll save big on your energy bill. Each degree cooler can add about 10% to the running cost.

The same principle applies in winter. If it's 10°C outside, try setting the indoor temperature to 18°C rather than 25°C (and wear a jumper if you have to). 

It also depends on the external temperature. Generally you'll get better efficiency by aiming for a maximum temperature differential of about 8°C. So on a 35°C day, set your indoor thermostat to 27°C. Realistically, most people will still go for a cooler temperature, but try not to go too far beyond that 8°C difference. You can probably aim for a bigger differential if your house is very thermally efficient (well insulated, double glazed etc).

Dehumidifying and "dry" mode

Whether the weather is hot and humid or cold and damp, excess dampness in your home can be a real problem. For persistent dampness, a dehumidifier might be the answer – whether a desiccant rotor model, which excels in cold damp conditions, or a refrigeration model, which is most effective in warm, humid conditions. See our dehumidifier reviews.

Your air conditioner is a good option for controlling warm humid air. Cooling mode not only cools the air but also removes some air moisture, which makes the air feel more comfortable. 

Many models also have a "dry" or "dehumidify" mode to dry the air, which is best used when the air is warm and very humid. The indoor fan speed is reduced so that the air spends longer moving over the cooling coils, in order to extract more moisture from the air. Dry mode can be an efficient and effective option in those conditions as reducing the humidity makes the air feel cooler and more comfortable. But when it's very hot and only moderately humid, cooling mode will be much more effective.

Noise

Check the air conditioner's noise levels; these can be found in the specifications and are listed in our review. Some models have a quiet mode for the indoor unit, and sometimes the outdoor unit too. This may reduce the cooling/heating power or airflow, but will keep the air conditioner running at a very quiet level.

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.

Noise is measured in decibels (dBA). Indoor noise levels for air conditioners range from 20 to 30 dBA on the lowest fan setting, up to 40 to 50 dBA on the highest speed. Outdoor units are typically in the 45 to 65 dBA range.

For comparison, here are some common sound levels:

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

Features and functions

Star-rating labels

Once you've worked out what capacity you need, compare the star ratings of models of similar capacity. The more stars, the lower the running costs and greenhouse gas emissions. Star ratings are different for heating and cooling.

The government energy rating website has more information about the star rating system and the rules for air conditioners.

A new star-rating label has been recently developed, giving more information about how the air conditioner performs in different zones of Australia, making it easier to choose a model best suited to where you live. This will be phased in over the next few years. We'll also start seeing new regulations and labels for portable and ducted models, to help consumers choose the most efficient models.

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.

Thermostat (temperature setting)

This controls the air conditioner to deliver the target temperature. Usually you just set the desired room temperature with the remote control, and the thermostat measures the indoor temperature and adjusts the air conditioner output accordingly.

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 actually in the room, so that the unit knows to keep working. When no one is detected, the unit might switch to an economy mode to reduce power consumption. Some models even direct the air movement towards the sensed person, so that the cooling or heating is mainly focused on the areas actually being used.

Remote control

Look for large, well-spaced buttons 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 more quietly) when you're sleeping.

Adjustable or oscillating louvres

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

A protective feature that prevents the air conditioner from starting up again too soon after being switched off.

Demand Response Enabling Device

Cooling and heating is a huge contributor to peak demand on the electricity grid. For example, on a stinking hot weekday, most people are going to turn on their air conditioners in the evening as they arrive home. To help reduce household power consumption, many new air conditioner models now feature DREDs (Demand Response Enabling Devices), also known as PeakSmart.

DREDs allow participating energy companies to remotely control the air conditioner in periods of peak electricity demand – usually in high summer when everyone wants to cool their homes – reducing both the strain on the grid and your household power consumption, without greatly affecting the air conditioner's performance.

How does it work? If you have an air conditioner with the DRED/PeakSmart feature, and your energy provider offers the PeakSmart service, you can arrange with your air conditioner installer to have a signal receiver installed on the air conditioner. In times of high demand on the grid, the energy provider will be able to remotely switch your air conditioner to an economy mode. This will usually have no major impact on the air conditioner's cooling (or heating) output – you might not even notice it happening – but will reduce the amount of power the air conditioner is using.

It can go a long way to reducing peak electricity demand and therefore the need for new infrastructure such as power stations. That means less cost passed on to consumers.

However, 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.

Other things to consider

When is the best time to buy?

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 go on sale as retailers make room for new models. While the newest models may be a bit more efficient or have new features, a recently superseded model at a bargain price can be a great choice.

Installation

Consider installation costs and requirements when you're shopping around. Here are some things to remember:

  • Most traders offer supply and install packages, and some installation only. Installation must be done by a licensed air conditioner installer, due to the refrigerant gas handling that's required. Look for an installer with ARCtick approval, and get a few quotes.
  • Cool air is heavier than warm air. So, for optimum cooling, the air outlet should be installed as close to the ceiling as possible, with the louvres pointing horizontally or upward. For heating, point the louvres downwards.
  • 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.

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

Do you live in a very hot or cold region?

  • Each model has a recommended outdoor temperature operating range. 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 cold area, frost may build up on the outdoor heat exchanger coils in winter if the air conditioner doesn't have automatic de-icing.
  • If you live in a hot and dry climate, an evaporative cooler can be a cheaper alternative to an air conditioner. Evaporative air coolers draw the hot air over a water reservoir. The water evaporates, absorbing heat from the air. The cooler, moist air is then blown into the room. Evaporative coolers are generally more suitable for hot areas with low humidity. CHOICE doesn't currently review evaporative coolers.

Refrigerant gas

Your split-system air conditioner uses a small amount of pressurised refrigerant gas to achieve cooling and heating. The gas is cycled between the outdoor and indoor units via connecting pipes, and it's how the system is able to transfer heat energy out of the indoor air (in cooling mode) or into it (in heating mode).

Since the 1980s the use of ozone-depleting refrigerants such as chlorofluorocarbons (CFCs) has been essentially phased out, and the atmosphere's ozone layer has shown good signs of recovery since. But the most commonly used current refrigerant gas type, hydrofluorocarbon or HFC, is also problematic; it's a greenhouse gas and as air conditioning becomes more common across the world, HFCs could become a major contributor to climate change.

In 2016 a new international agreement was reached, to phase out the use of HFCs over the next few decades and find better alternative refrigerants. We're already seeing a trend towards recent models using R32 refrigerant instead of R410A; these are both HFCs, but R32 has a lower global warming potential and should also give improved efficiency.

Looking for the best air conditioner?

See our expert product reviews.

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