Getting the size right! - Air Conditioning Brisbane Northside | Expert Repairs & Installation | Call 1300 222 747

Getting the size right!

There’s nothing better than lying around watching TV, getting some work done in your office, or going to sleep, in a perfectly cooled room.

But how do you find the perfect sized air conditioner to suit all of your different living area requirements, that will run efficiently and affordably all year round?

This question confuses a lot of potential buyers and the short answer is speak to a professional Air Conditioning Technician!

But for your own knowledge, here’s some helpful information about why it’s so important to install the right size system and what factors we take into consideration.

Why is it so important to get the correct size Air Conditioner?

Bigger is not always better!

Modern air conditioners run optimally when they are sized according to the conditions.  An energy efficient air conditioner is designed to run in cycles to slowly cool your house, instead of doing it rapidly.

If your air conditioner is too big, often it will cool down your house quickly and then turn off, before it goes through the entire cycle that it is designed for. Your house will begin to warm up, then it will turn on again, etc etc. This 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.  This means that it won’t work efficiently and will cost you significantly more in electricity.

What factors affect the size of air conditioner?

  1. Size of House – As we mentioned the size of the room is crucial to selecting the correct, most energy efficient size.
  2. Insulation – This will greatly affect your house’s ability to maintain its temperature. If your house is well insulated, you likely won’t need as much heating or cooling capacity compared to one with poor insulation.
  3. Climate – What type of heat do you have? The tropical and sub-tropical areas of Australia tend to have much greater demands.
  4. Lighting/Windows/Walls/Floors- What type and how much lighting you have, your type/quantity of ducting, the number of windows and efficiency, the heat transfer between the walls, the number of skylights, the amount of people in your home and the type of foundation/flooring.

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

You can calculate the size yourself using a formula below.   It’s a good way to get a general idea of your needs, but if you’re after a truly accurate understanding it’s best to use an online calculator or have a technician come out, before you commit to anything.

The Formula –

Step 1 –

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.

Step 2 –

What you do next will depend on your ceiling height:

  • If your ceiling is 2.4m high, you will need to multiply the day time 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)

Step 3 –

These calculations will give you the amount 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.

Alternatively please try one of the many online calculators or apps on the market to find the correct air conditioning sizing for your house or office.  We can recommend the Panasonic Sizing Wizard App that is very simple and easy to use, and you can download from Google Play or the App Store.

The most accurate way to find out the air conditioning capacity that you will need for your home or office however, is by getting a professional to come in and calculate it. They will take each factor into consideration and help to make sure that you have the perfect sized air conditioner for your home.


Leave a comment

Please note, comments need to be approved before they are published.