What Size Air Conditioner Do I Need? The Definitive Guide

Phill Crawley

Smarter Air & Electrical

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What Size Ducted Air Conditioner Do I Need?

When the time comes to choose an air conditioner, one of the first questions you will ask yourself is what size air conditioner I need to heat and cool my home.

Many people head straight into their local electronics retailer and take the advice of one of the sales reps on the floor, which can be a costly mistake.

Did you know the air conditioning trade requires a 4-year apprenticeship? Qualified air conditioning technicians are taught how to properly size an air conditioner based on home size, layout, location and more. On the other hand, sales reps at these large retailers often work from rough guides provided by the manufacturer. They use data based on averages, resulting in oversized equipment that will provide you with cool air and cost you more to run.

Let’s say you need to cool a small home office. You tell the sales rep I need to cool a study and the room size is 9 square metres — if he immediately tells you what size unit you need, that should be a red flag!

Here are the questions a trained professional will ask:

  • Is the home one storey or two storeys
  • Is the study upstairs or downstairs
  • Does the study have any windows
  • Do the windows have blinds/curtains
  • Is the ceiling insulated
  • What is the ceiling height
  • What is the roof made from
  • Is their insulation under the roofing material
  • What colour is the roof

Without the answers to the above questions, you will only be getting a rough idea of what size ducted air conditioning system is correct for your home. A home with a black tin roof with no insulation and no ventilation will require a more oversized, more powerful air conditioner than a home with a white tin roof with Bradford Anticon blanket insulation and adequate roof ventilation.

So when it’s time to choose your next air conditioner, make sure you ask a professional what size air conditioner is most suitable before you push the button and make a purchase. Buying from a professional air conditioning installer over a large retailer may cost you a little more upfront. Still, their experience and expert advice will pay dividends over the life of your system. Choosing a quality contractor will help you save money on your power bill with running costs and ensure you get the correct cooling capacity for your home.

How Do People Affect The Size Of The Air Conditioner?

According to the 1992 CSIRO/AREMA (Air-Conditioning & Refrigeration Equipment Manufacturers Association of Australia) method and factors, people add extra load depending on their activity. For example, cleaning a house will add more heat to a room than resting on the lounge.

  • Sitting: 72 watts
  • Light Activity: 80 watts
  • Heavy Activity: 90 watts

In 2016, the average Australian home had 2.6 people. If they were both doing a light activity such as cooking, this would only add 160 watts, which is not a great deal when you consider that the most common ducted air conditioning system we install is a 12kW (12000 watts).

Do Electronics Increase The Size Of The Air Conditioner I Need?

Absolutely! Have you ever been to a hair salon and found that the air conditioner cannot cope? Often this is because the air conditioner is not sized correctly to take the extra heat load from all the equipment in the salon. Let’s break it down a little. Below is a list of the average power consumption of electronic equipment in a hair salon.

  • Hair Dryer: 2000 watts
  • Hood Dryer: 1800 watts
  • Wax Pot: 100 watts
  • Kettle: 2000 watts
  • Straightener: 35 watts

The power consumption of these electrical appliances needs to be considered when sizing air conditioning capacity, especially in the case of a hair salon where you might have four of each piece of equipment totalling 23740 watts or 23.7kW. The other thing that your air conditioning contractor will keep in mind is that these devices don’t run 24/7. More than likely, there will only be one or two of these used at any one time, bringing our 23.7kW down dramatically and reducing the necessary size of the air con.

How Is A Professional Quote Calculated?

To create a rough estimate at the start, many air conditioning contractors take the square meters of your home floor space and multiply it by a calculated average kilowatt per square meter relative to your location. In Brisbane, this is commonly 0.16 kilowatts per square meter. So if your living room is 36 square meters, you multiply 36sqm*0.16kW = 5.76kW required cooling capacity.

Once calculated, your contractor can provide you with a quote estimate. If you are interested in moving forward, they will visit your home to assess any factors outside of the norm regarding the construction of your home and how you use it. If anything catches their eye on this visit, they will offer their recommendations and possibly reduce or increase the size of the system to match the requirements.

We recently completed a site inspection for a customer with six ASIC Bitcoin miners in his spare bedroom. Each of these Bitcoin miners consumed 3250 watts of electricity, and these devices run 24/7, so this means we needed to add 19,500 watts (or 19.5kW) of extra cooling capacity to his system. Rather than increase the size of his ducted system, this particular client decided to relocate the bitcoin miners outside of the home to an insulated shipping container with appropriate ventilation to remove the excessive heat.

As we mentioned previously, it’s best to engage a qualified Arctic RAC01 Certified Cert 3 Air Conditioning Mechanic (such as Phill from Smarter Air L026211) to look after your heating and cooling needs. A qualified air conditioning technician will ensure your air-con system has appropriately sized for your home and lifestyle.

Get In Touch With Smarter Air & Electrical

Ensure you have the correct size air conditioner that’s optimised for your home with Smarter Air. We specialise in ducted air conditioning from leading brands such as PanasonicMitsubishi Heavy IndustriesSamsung and TECO. We are also authorised Airsmart professionals, the world’s most innovative heating and cooling system. It redefines air purification and comfort with its unique Indoor Environment System (IES) for unrivalled control.

We only use trusted, world-class brands and offer a 10-year workmanship guarantee on all installations to give you peace of mind your AC will be keeping you comfortable for years to come. Get in touch with our friendly team today and get a free quote.

T B
My wife and I had Smarter Air & Electrical install ducted system in our home. Benji and team arrived on time, they were extremely polite ...
T B
My wife and I had Smarter Air & Electrical install ducted system in our home. Benji and team arrived on time, they were extremely polite and friendly. Benji was professional and had great communication and was always happy to help and answer any questions we had. The team were amazing, everything was done at a high standard. They also left our home clean and tidy. We would definitely recommend them. Thank you again. Tavis and Kelly
T B
T B
Zana Toki
Excellent to deal with and highly recommend. It was very simple process from getting a quote to organizing install. The team that installed were great, ...
Zana Toki
Excellent to deal with and highly recommend. It was very simple process from getting a quote to organizing install. The team that installed were great, Very professional and efficient! The removal of the old split systems and install of ducted was completed fast and everything left clean and tidy afterwards. Would definitely recommend!
Zana Toki
Zana Toki
A.V
All of the staff were amazing. From the two guys who came out to talk to us about our requirements to the team of guys ...
A.V
All of the staff were amazing. From the two guys who came out to talk to us about our requirements to the team of guys who attended on the day of installation. They were very thorough, extremely neat and nothing was a problem. They cleaned up after themselves and made sure we understood exactly how the system worked before leaving. I would not hesitate to recommend Smarter Air & Electrical as professional, pleasant and hard working guys who know exactly what they are doing.
A.V
A.V
Amanda Robinson-Ilka
We did a lot of research regarding air conditioning providers before engaging Smarter Air and Electrical. From the initial phone call with the lovely...
Amanda Robinson-Ilka
We did a lot of research regarding air conditioning providers before engaging Smarter Air and Electrical. From the initial phone call with the lovely Amanda, to the onsite consultation with Davis, through to installation by Tom and the team, the whole process has been seamless, with the entire team being friendly, professional and easy to work with. They left our house clean and tidy after a full day's work. We are very pleased with our ducted air conditioning solution, with a split system for downstairs. Bring on summer. 🌞
Amanda Robinson-Ilka
Amanda Robinson-Ilka
steven Johnman
Thanks to Benji and his crew from Smarter Air & Electrical for installing the new ducted air conditioner system, it was good to see that ...
steven Johnman
Thanks to Benji and his crew from Smarter Air & Electrical for installing the new ducted air conditioner system, it was good to see that they took all of the packaging away and tidy up the work areas.Benji took the time to show me through the setup process for the tablet . Bring on summer.
steven Johnman
steven Johnman
Rebecca Robinson
Great communication from both Alex who helped assist with the quote and Jack who installed the aircon on the day. I live in a townhouse ...
Rebecca Robinson
Great communication from both Alex who helped assist with the quote and Jack who installed the aircon on the day. I live in a townhouse so I was limited with my options but the team went above and beyond to make sure I was happy with the end product. Would happily recommend to others.
Rebecca Robinson
Rebecca Robinson
John Ngai
Team was efficient and there was consistent communication along the process. On-site visit was helpful in determining optimal location of external unit and location of ...
John Ngai
Team was efficient and there was consistent communication along the process. On-site visit was helpful in determining optimal location of external unit and location of internal return vent and controls. Team did a great job during installation. Would recommend service from Smarter Air for those considering air conditioning service and installation.
John Ngai
John Ngai
George Adam
The guys were amazing went through everything from start to finish. Did a great job installing Cleaning as they went looks great .
George Adam
The guys were amazing went through everything from start to finish. Did a great job installing Cleaning as they went looks great .
George Adam
George Adam
ashcroftracing
The whole experience of dealing with the team at smarter air has been amazing! Day of install could not rate there team enough, very polite ...
ashcroftracing
The whole experience of dealing with the team at smarter air has been amazing! Day of install could not rate there team enough, very polite tradesman and very professional in how they did their work. Massive credit to this team from first call to end product
ashcroftracing
ashcroftracing
Mick McIntyre
Thank you very much to everyone at Smarter Air & Electrical. From the quote and related queries, great recommendations on upgrades that we...
Mick McIntyre
Thank you very much to everyone at Smarter Air & Electrical. From the quote and related queries, great recommendations on upgrades that we hadn’t even thought about, outstanding communication in job preparation and scheduling, and a really top bunch of guys on installation day… we can’t thank your whole team enough!! Many thanks, and a big dose of gratitude to all of you. Looking forward to a far more comfortable Summer ahead 🙂
Mick McIntyre
Mick McIntyre

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