For most homes, a reverse-cycle 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 are the most common air conditioner type in Melbourne and are good for a room or open plan area up to about 60m2.

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. About the same price range as the equivalent separate split-systems. Contact us now for a free quote

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. Call now for a free quote 

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

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

Room SizeCapacity

Up to 20m2 - 2-2.5kW

20–40 m2 - 2.5–5kW

40–60 m - 4–6kW

60–80 m2 - 5–7kW

80+ m2 - 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 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.

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 Brisbane will probably need a more powerful air conditioner compared to an otherwise identical room in Melbourne.

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.

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:

Small (up to 4kW) $242–$492

Medium (4–6kW) $402–$552

Large (over 6kW) $442–$586

* 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.

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 for best efficiency 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 of your air conditioner.

Does an inverter air conditioner save money?

Solar powered air conditioners

Read more: Air conditioner energy saving tips

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