Frequently Asked

What Size Air Conditioner Do I Need?

The Australian heat can be unbearable in the summertime, and good quality air conditioning is the best way to stay comfortable when things get sweltering. One thing that confuses a lot of potential buyers is the size of air conditioner they will need.

This guide will provide some clarity and go through all of the details to give you a clearer picture of what you might need for your home.

Introduction to air conditioning 

The first step in finding the right sized air conditioner is to understand their unit of measurement. In Australia, the output of air conditioners is measured in Kilowatts (often expressed as kW). Kilowatts are one thousand watts, which is a measure of energy over time.

Why is it important to get the right size?

The short answer is efficiency. Although it might seem that bigger can only be better, that is not the case with modern air conditioners. Instead, air conditioners run optimally when they are sized to the conditions. A bigger unit may end up costing you more in energy bills and become an unnecessary bill for your household. An energy-efficient air conditioner is designed to run in cycles that will slowly cool your house instead of doing it rapidly.

If your air conditioner is too big, oftentimes, it will cool your house down quickly and then turn off, before it goes through the entire cycle that it is designed for. Your home will begin to warm up, and then it will turn on again, quickly cool down your house and then turn off again. This whole on-again, off-again cycle can end up using much more power than a properly sized air conditioner would.

If your air conditioner is too small, it will be in constant overdrive as it tries to keep up with the large space. It should still be able to keep your house cool unless the unit is way too small, but it won’t be running the way it is designed to. This constant running at a high level will mean that it is not working efficiently and will cost you significantly more in electricity.

What factors affect the size of air conditioner that I will need?

Air conditioning is much more complicated than it may seem at first. The size of your house is important in determining your air conditioning needs, but there are also many other factors that can have a surprising amount of influence on the size of air conditioner that will best suit your home.

The amount of insulation in your house is a crucial consideration because it can affect your house’s ability to maintain its temperature. If your home is well insulated, you likely won’t need as much heating or cooling capacity as one with poor insulation.

Another prominent factor is the climate that your home is located in. The tropical and subtropical areas of Australia tend to have much greater demands than the cooler regions of Australia. Due to Australia’s climate, you also need to consider the capacity of your unit.

If you are in temperatures that exceed over 35C, you will find that your air conditioning unit will decrease in efficiency and lose more cooling capacity. If you have a 14kW system operating in temperatures over 35C, you might find that unit is reduced to a 10kW or 12kW capacity.

Some other factors that influence the size of air conditioner that you will need include

  • What type of lighting you have
  • How much lighting you have
  • Your type and quantity of ducting
  •  The number of windows and their efficiency
  • The amount of heat transfer between walls
  • The number of skylights
  • The number of people living in your home
  • The type of foundation your home is built on

And several other factors. As you can see, it’s quite complicated.

 How do I calculate the size of the air conditioner that I will need?

The three main ways to calculate your air conditioning needs are:

  • Using a formula
  • By using an online calculator, or;
  • By getting a professional to visit your home to calculate things precisely

With the ActronAir Power Cooling Calculator, you can stop the guesswork and find the perfect system for your home.

Using a formula to calculate your air conditioning needs

Using a formula to estimate your air conditioning needs is quick and easy, but it’s also very rough and doesn’t consider many of the important factors outlined above. It’s an excellent way to get a general idea of your needs. Still, if you’re after a truly accurate understanding, it’s probably best to use one of the other two methods before you commit to anything.

To estimate the amount of air conditioning you will need for your daytime living area, you will first need to determine its area. You will need to find the length and width of each room and multiply them. Then, you have to add the area of each room together for the total. This figure needs to be in square metres.

What you do next will depend on your ceiling height:

  • If your ceiling is 2.4m high, you will need to multiply the daytime living area (m²) by 150 (watts)
  • If your ceiling is 2.7m high, you will need to multiply the daytime living area (m²) by 160 (watts)
  • If your ceiling is 3m high, you will need to multiply the daytime living area (m²) by 175 (watts)

These calculations will give you the number of watts you need, and you can then move the decimal point three points to the left to convert it to kilowatts.

As an example:

For a house with a daytime living area of 100m² and a height of 2.4m, the calculations would be:

  • 100m² x 150 watts = 15,000 watts
  • 15,000 watts = 15 kilowatts

A 15kW unit is roughly the right size for this house.

Using an online calculator to figure out your air conditioning needs

Using an online calculator will give you a more accurate estimate than the above method, but you will also have to consider more factors. Fairair ( has a good calculator that will help you figure out the number of kilowatts you will need.

The ActronAir Difference

Not all air conditioning units are designed to keep operating at their normal capacity in extreme weather. At ActronAir we understand the need for hardy air conditioning units. That’s why our units can operate up to at least 50C – unlike other units on the market.

ActronAir systems like the ESP Platinum, ESP Plus Series 2 and the Classic Series 2 all have optimal ranges up to 50C, while our Advanced unit has an operating range up to 54C. 

Using a professional to figure out your air conditioning needs

The most accurate way to find out the air conditioning capacity that you will need for your home is by getting a professional to come in and calculate it. They have years of experience, which they can use to get the most accurate estimate of your air conditioning needs. They will consider each factor and help ensure that you have the perfect sized air conditioner for your home.

In order to buy a system that will perform in Australian conditions, ActronAir units are designed to operate, even in more extreme conditions. ActronAir units are designed by Australians for Australian environments.

To learn more about ducted systems, see our dedicated page on ActronAir ducted systems. ActronAir prides itself on the high quality of our Dealer network, so contact us today to arrange a free and obligation-free visit.

If you want a system that better maintains its optimal range, you better ask for an Actron. 

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