What size air conditioner do you need in Australia? (2024)

Depending on where you live, the same kilowatts of cooling capacity will be more or less effective. In Mild zones up north the air conditioner has to battle higher heat and humidity, and therefore needs to work harder than it would in Cool or Cold zones like Victoria and Tassie.

The 125 watts of cooling capacity per square metre we mentioned earlier, shifts depending on where you're located in the country. Here's how that breaks down according to Fair Air's calculator.

How your home is built plays a vital role in keeping it cool, and how much cooling efficiency you'll need. Everything from the floor type, to the roofing, to window size and coverings, and even the position of the room itself within the home will play a part in how much capacity is required to cool it down (or heat it up for that matter).

For example, a 20m2 room is Sydney in a weatherboard house with no insulation, wood floors, and a tin roof, with two large east facing windows requires 3.4kW to adequately cool it. With roof insulation this goes down to 3.3kW, and with wall insulation it drops to 3.2kW.

While a whole new roof or floor might not be in the budget, there are cheaper ways to lower the cooling load of a room. Adding high quality, external window shades can keep the heat out. Internal shading like blinds does help a little bit, but they still allow a lot of the heat to permeate the room before it is blocked. You an also fill up gaps and holes around windows, doors, and floors.

Finding the right air conditioner size really is a Goldilocks situation. You don't want something too big and is going to cut into your budget, and leave you uncomfortable. But you also don't want something too small which will ultimately do the same thing but in a different font. You're really looking for your bowl of porridge, or your glass slipper.

While we can give you some solid ideas as to the size you'll need, your best bet is to go through a detailed calcultor like the one found on Fair Air. This takes everything we have covered into account, and can even give you an idea of what else you could do to bring down your current cooling requirements.

Of course you may not be able to find an air conditioner that is the absolute perfect size, and if that is the case we do recommend going slightly larger than you'll need. While there are trade-offs like higher power usage, and lacklustre dehumidification, they're generally better than what you'll experience with units that are too small. Smaller units usually need to run at a higher capacity for longer which can in turn dry out the air, increase your usage costs, and put more pressure on the system leading to a shorter shelf life.