How to choose an air conditioner

Air conditioner

An air conditioner, AC or aircon, is a mystical machine that makes our lives more comfortable. You are (hopefully) unlikely to buy many in your life. When you do, you’ll probably seek out a specialist who knows more about AC than you do. Unfortunately, that specialist will likely peddle what they want rather than what you truly need or is the best deal. Luckily, we’re here to help you navigate the minefield that is buying an air conditioner.

Types of air conditioner

split aircon

An air conditioner works on the same principles as a fridge. It is, for now, the most economical way to heat and cool a living space. Energy efficiency has improved substantially over the last 20 years to the point where some machines deliver the same effect using one-fifth of the electricity.

The type of air conditioner you buy will depend on your objectives and the physical structure of your house. An air conditioner can be purchased as a cooling-only model or reverse cycle, which will both heat and cool. The different types of air conditioners are:

  • Portable – A freestanding unit usually on wheels that can plug into a standard powerpoint. It does require a ducting air pipe to be connected to a window baffle kit that allows hot air to be expelled outside. Easy self install. Great for renters or for people not wishing to do a permanent installation. Not as efficient as other types and does require a water tank to be emptied periodically. Generally only available as a cooling-only unit.
  • Window/Wall – All in one box that is inserted into a window opening or hole in a wall. Relatively cheap to buy but can be noisy and unsightly to look at.
  • Split – The most common type of air conditioners installed today. Comprises of a separate indoor and outdoor box and connecting tubes. Does require professional installation but only requires about a 10cm hole to connect the outdoor and indoor unit through your wall. The unit is quiet as noise is made by the outdoor unit. The indoor unit is relatively small and can be positioned up to a manufacturer-specified length away from the outdoor unit.
  • Multi Splits – Are the same as a split system but support multiple indoor units from the one outdoor unit. Thus you can heat or cool separate rooms in a house with the one outdoor unit.
  • Ducted – All the workings can be hidden away from view except for an air vent in your ceiling or floor and a thermostat somewhere in the house. A ducted system is a whole house system and generally installed when the house is built. This solution requires large air ducts to run to each room in wall and ceiling cavities. Installation is complicated, and most likely, 3 phase power will also be needed. It is much harder to install a ducted system in an existing house.
  • Industrial – These are systems designed for commercial environments such as an office block.

Tip: When deciding on an air conditioning solution beyond a portable unit, it is a good idea to get a quote/opinion from more than one air conditioner provider/retailer/installer.

Size means power

‘Size’ in the case of an air conditioner is not how big in dimensions. Instead, this refers to how powerful a unit is needed to be effective in the area you are looking to heat or cool. A unit that is too small or too large will be ineffective.

The heating and cooling capacity of an AC is measured in kilowatts (kW), which is the unit’s output, not the electrical input. The good news is the input is significantly less in electricity terms to get the heating/cooling output. Essentially, the bigger the number, the more powerful the unit and its ability to heat and cool a larger room.

To accurately determine the right size for your room you should use a calculator. The calculator will take into account criteria like:

aircon calculator
  • The floor space of your room
  • The height of your ceiling
  • Where you live in Australia
  • Is the room on a northern wall or a western wall (effect of the sun)
  • The number of windows you have
  • The kind of materials you used for your roof: tin or tiles
  • The number of people usually in the room
  • house construction materials
  • What appliances are in the room
  • The insulation type (if any) in the ceiling and walls

As a very rough guide for a standard brick veneer house with insulation for a split system:

Floor AreaRoom typePossible requirement
Up to 20m squareBedroom2-2.5kW
20 -40m squareBedroom with ensuite2.5-5kW
40-60m squareMid-sized lounge4-6kW
60m square plusOpen plan area5-9kW
Keep in mind that an AC in Darwin will have to work harder to cool, while a unit in Melbourne will have to work harder to heat.

Tip: Most vendors and installers will have a calculator on their website to help you decide which size is right for you.

Designed not to be seen

‘Design’ is a funny concept when it comes to air conditioners because we really don’t want to see them at all. The best scenario is that an AC is hidden from view entirely. If it is visible, then it should be neutral in colour, small in size, pleasing in shape, and quiet.

Although occasionally a vendor brings out something a little more stylish, most air conditioners look quite similar. If yours will be noticeable, be mindful to choose the right base tone of white to match your wall’s paint. While they all might appear ‘white’ in a showroom or on a web page, some may be cream-based, while others are grey-based.

Tip: if technically possible, don’t let the installer position the AC in the most convenient spot for the installation; ask if it can be moved to a less noticeable position.

Key features to consider when buying a air conditioner:

  • Inverter Motor – Standard motors will switch on then off, keeping a room temperature within a temperature range. An invertor motor allows the motor to run continuously, but at a slower speed meaning the temperature variation is less. The unit is more economical.
  • Ioniser – removes germs, virus, bacteria as well as reducing mould
  • Dehumidify – allows moisture to be removed from the room without either heating or cooling the room. Thus remove humidity.
  • Sleep mode – feature to allow an air conditioner to slowly reduce the cooling over a period of time after you go to bed.
  • Filter – if installed, removes dust and unwanted contaminants in your air. (filters will need to be cleaned and replaced)
  • Anti Corrosion – techniques used in manufacturing to ensure the unit lasts longer, especially if exposed to salt air.
  • Warranty – A air conditioner should last you 10 years or more. Indeed, some brands offer up to a 10-year warranty on the compressor only, which is the most common failure. In the unlikely event your air conditioner does fail, and your warranty has run out, you may still be able to get it repaired under Australian Consumer Law.
  • Internet-connected – All air conditioners will run without an internet connection. Still, some offer additional benefits like controlling the air conditioner from an app on your phone or asking your virtual home assistant (i.e. Alex or Google Home smart speaker) to turn the air con on to 22 degrees. Other handy features that may exist include being able to monitor energy usage and change heating/cooling modes.
  • Efficiency – Each air conditioner in the retailer showroom will have an energy star rating and Kilowatt-hour rating (kWh) on a sticker. The more stars out of 10, the more energy-efficient the aircon is. There will be a rating for cooling and a rating for heating, assuming it is a reverse cycle unit. The rating will also be classified depending on where you live in Australia. The cost of running the aircon each year will be the input kWh times the cost per Kwh hour you pay for electricity. E.g. if you paid $0.30 per Kwh and your aircon consumed 1000 kWh/yr, the cost would be $300 per year in electricity.
energy star rating

Trends in AC

Smart homes are becoming a thing, and air conditioning is a natural fit. The ability to switch your aircon on remotely on a hot day makes your home comfortable on arrival. Airflow is key to moving air, and more efficient fans are being introduced to spread the air further. Technology also exists that uses waste heat from a cooling solution to heat water, thus effectively saving you on electricity to do this separately. Finally, we want an air conditioner to not be seen or heard, so new ways to reduce noise are in the pipeline.

smart home

Finding a quality installer

Before making your final decision, it is a good idea to check the experience others have had with your air conditioning installer. Review sites, including Google, will quickly give you an idea. Poor workmanship can lead to water leaks in your house or damage to your outdoor unit.

Which air conditioner should I buy?

Since there are so many models currently available in retailers, we recommend you go with the more popular brands and not the cheapest. Walking around a retailer, you will soon see which brands are popular as they will have more display models than others. Also, look out for stickers from consumer advocacy groups who do testing and have subsequently found a certain model to be better.

After reviewing this article, make some notes on what is important to you and how much you want to spend. Once you have picked your model, don’t be afraid to haggle on price.