Calculating the correct size of a split system air conditioner for a room in Australia involves several factors such as the size of the room, insulation, number of windows and doors, the location of the room, and the local climate. Here are the general steps to follow:

Measure the size of the room: Measure the length, width, and height of the room in meters to get the total cubic meters. Multiply the three measurements to get the room’s volume in cubic meters.

Which direction does the room face: Consider the room’s position in the house and the direction it faces. North-facing rooms receive more direct sunlight and may require more cooling than south-facing rooms.

Is the room insulated: The level of insulation in the room affects the cooling capacity needed. A well-insulated room requires less cooling capacity than a poorly insulated one.

How many windows and doors: The number and size of windows and doors in the room affect the cooling load. North facing windows and doors that face the sun will require more cooling.

Where is the location of the room: The location of the room in the house can affect the cooling load. For example, a room on the top floor or one with a flat roof will require more cooling than a room on the ground floor or one with a pitched roof.

Calculate the heat load: Consider any heat-generating appliances in the room, such as computers, televisions, and lights. Calculate their heat output in watts and add them together.

What’s the local climate: The local climate will affect the cooling load. For example, a hot and humid climate will require more cooling than a dry climate.

Use a sizing chart: Use a sizing chart provided by the manufacturer to determine the required cooling capacity of the air conditioner. The cooling capacity is usually measured in kilowatts (kW)

Use a calculator: There are online calculators that can help you calculate the cooling capacity needed for a room. One example is the Cool or Cosy air conditioning calculator, which takes into account the factors mentioned above.

Select an air conditioner: Choose an air conditioner with a cooling capacity that matches or exceeds the required capacity.

Consult a professional: It’s always a good idea to consult with a professional heating and cooling air con installer to ensure you’re choosing the right size split system air conditioner installation for your room. They can help you take into account any other factors that may affect the cooling load and ensure that the installation is done correctly.

It’s important to note that oversizing or undersizing an air conditioner can result in reduced efficiency, increased energy costs, and decreased comfort. It’s best to consult with a licensed air con installer to ensure the correct sizing of your split system air conditioner for optimal performance.