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What size air conditioner is best for my home?

  • Wednesday, 7th March, 2018

The heat in Australia can often be unbearable during the summertime, and a good quality air conditioning unit is the best way to stay comfortable when things get hot. One thing that confuses a lot of Australians is the size of the air conditioner they will need for their home.

An undersized unit will work harder yet not reach the set temperature on those very hot or very cool days – and isn’t that the time when you want your system to work its best? An oversized unit will cost more to operate and most likely be inefficient to run.

Of course, getting the right sized system is very important. You don’t have to be confused anymore, because this guide will give you a clearer picture on what you might need for your home.

Why is it important to get the right size?

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

Efficiency is key. Although it may seem that ‘bigger is better’, this is not the case with modern air conditioners. Instead, air conditioners run best when sized appropriately. An energy efficient unit is designed to run in cycles that slowly cool your home, instead of cooling it rapidly.

If an air conditioner is too big, often times your house will cool down too fast and then the unit will turn off before the cycle is completed. Your house will begin to warm up, the unit will turn on again, quickly cool down the house, and then turn off again. This repetitive on-again, off-again cycle can end up using more energy and power than a properly sized air conditioner would. Adversely, if your air conditioner is too small, it will work in overdrive to try to keep up with the large space. This constant running at a high level will mean that it is not working efficiently and will cost you significantly more in electricity, as well as placing stress on the system causing the life of the unit to be drastically shortened.

How do I calculate the size of what I need?

The main ways to calculate air conditioning needs are:

  • With a formula, or;
  • By getting a professional to visit your home to calculate things precisely

Using a formula

Using a formula to calculate your air conditioner needs is quick and easy, but only gives a rough estimate, as it doesn’t take into consideration factors such as insulation or climate. It is a good way to get a general idea of your needs.

To estimate the amount of air conditioning you will need, you will first need to find out the area for your daytime living space. To do this, you 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 amount of watts you need, and you can simply move the decimal point three places to the left to convert it to kilowatts.

As an example:
An average sized Brisbane home has a daytime living area of approximately 85m² and 2.7m high ceilings, the calculations would be:

  • 85m² x 160 watts = 13,600 watts
  • 13,600 watts = 13.6kW

Using a professional

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

Here at Quality Air we pride ourselves on the high quality of our work, so to arrange a free and no obligation visit, why not Request a Quote?