What Size Air-Con do I need?

Choosing the right size air-conditioning unit and finding the perfect location for absolute efficiency in your home (meeting all legal requirements) can be a headache. Never fear! Triforce Electrical and Air is here! We have considered all the variables for you and put together an easy to understand guide – hopefully.

Selecting the right unit

In order to help you choose the perfect unit for your home, make a note of the following factors:

  • Room size
  • Ceiling height
  • The wall you would like the unity to be installed on?
  • How much space in on the wall?
  • Is the roof space insulated?
  • Are the wall cavities insulated?
  • Are there large glass windows and/or doors? Do they get direct sunlight? Are they glazed or double glazed?
  • Does the room get direct western sunlight?

What Air Conditioner size do you need?

In a standard insulated Brisbane, QLD home, you will usually require a 2.5kW system for a bedroom and 7kW for your lounge room.

You’re unlikely to require other sizes unless your home is uninsulated, has lots of windows, is western facing or has significantly high ceilings.

You can reduce the load on the air-conditioners by closing all your blinds and shutters, but most Queenslanders love the sunshine and want to take full advantage of its beauty, so this will make a difference on the size of the unit you need.

Don’t forget that you will need to have a regular 12-monthly air-conditioning service to keep your unit in tip top shape!

For all the technical people out there who want the specifics

Firstly measuring the room that requires to be cooled, multiply the room’s width by its length (LxW), then multiply this value by 140 to get the number of watts required.

Why 140? Here at Triforce we think the magic number to promote efficient cooling and heating is 1.4kW per 10 square meters so 140 watts – which is what we will use for our example.

For example using the above image:

A 4m by 3m room = 12 square meters

Wattage required: 12 x 140 = 1680watts (1.68Kw)

Therefore, a 2.5kW system will provide adequate and ample cooling for a room of 12 square meters.

Why not a smaller unit? You still need to add in the factors of windows, doors, sunlight, home positioning and days with extreme temperatures (when you will need your system the most).

What about heating?

Most split systems have an extra kW power rating for heating compared to cooling. Therefore, if the system is able to cool the room efficiently it will also heat it easily.

How much space is required for installation?

Most people don’t give this question any consideration, but it’s another important aspect of a quality installation. Here are the minimum spaces needed for an efficient installation.

  • Small units require 900mm (w) x 300mm (l) of empty wall space
  • Large units require 1150mm (w) x 350mm (L) of empty wall space
  • The largest outdoor unit is 800mm wide x 1100 high nad you need to allow roughly 300mm minimum clearance in every direction

You also need to think about what is on the other side of the wall!!! Is your hot water tank. security cameras, piping etc in the way?

I’m so confused, what else can I do?

If you are still confused after reading these guidelines, send us a few photos of your home and we can work out where to put your air-conditioning unit for you. If you also send us a basic floor plan, this can also help us to plan the logistics of the installation.

It’s important to let us know if there are any possible issues before installation, so we can give you an accurate quote, and have the right employees on the job to allow for an efficient installation.

Find the right professional electrician to help you

Triforce Electrical is a trusted, Brisbane local and professional business that can assist you with all of your residential electrical needs. We understand the importance of choosing the right air conditioner for your home. We believe in doing it once do it right. If you want an air con supplied and installed call us to discuss your electrical needs.


ARCtick Licence: L114709 AU53510
Triforce Electrical and Air PTY LTD (electrical contractor licence): 83596

© 2021 Triforce Electrical and Air | Site by GO Creative