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.

Tiffany Smith
Jack & his team were amazing. The entire team at Smarter Air have been extremely helpful & have gone over & above to get my ...
Tiffany Smith
Jack & his team were amazing. The entire team at Smarter Air have been extremely helpful & have gone over & above to get my home air conditioned as quickly as possible. Amanda in the office has been particularly helpful when I needed to navigate some tricky body corporate issues & wet weather delays. Jack & his team for installation were always on time , polite , respectful of my home & cleaned up after their work every step of the way. This is a very well run local company.. Thank you for being so good at your job..
Tiffany Smith
Tiffany Smith
Helen Luafutu-Tofilau
We had the Samsung ducted system installed in our home today. The team arrived on time, they were absolutely amazing, very professional, polite and friendly. ...
Helen Luafutu-Tofilau
We had the Samsung ducted system installed in our home today. The team arrived on time, they were absolutely amazing, very professional, polite and friendly. They were very respectful of our home and were able to work around our family as we were all home at the time of instilation due to school holidays. Everything was done at a high standard, and the boys were never too busy to answer any questions we had. They also left our home clean and tidy inside and out. We would definitely recommend them. Christmas has come early for us. Thank you again Sam and Helen
Helen Luafutu-Tofilau
Helen Luafutu-Tofilau
Helen Luafutu-Tofilau
We had the Samsung ducted system installed in our home today. The team arrived on time, they were absolutely amazing, very professional, polite and friendly. ...
Helen Luafutu-Tofilau
We had the Samsung ducted system installed in our home today. The team arrived on time, they were absolutely amazing, very professional, polite and friendly. They were very respectful of our home and were able to work around our family as we were all home at the time of instilation due to school holidays. Everything was done at a high standard, and the boys were never too busy to answer any questions we had. They also left our home clean and tidy inside and out. We would definitely recommend them. Christmas has come early for us. Thank you again Sam and Helen
Helen Luafutu-Tofilau
Helen Luafutu-Tofilau
Cara Macarthur
The Smarter Air & Electrical team from start to finish (order to install) has been nothing short of amazing! Great products, great service and impeccable ...
Cara Macarthur
The Smarter Air & Electrical team from start to finish (order to install) has been nothing short of amazing! Great products, great service and impeccable workmanship! Benji and his install team were probably the highlight of the experience, well mannered, punctual and a friendly bunch!
Cara Macarthur
Cara Macarthur
Arthur Cowell
Great service! Full ducted install which took just over half the day, team were quick, professional and respectful when moving around the home and wishing ...
Arthur Cowell
Great service! Full ducted install which took just over half the day, team were quick, professional and respectful when moving around the home and wishing to use facilities. Support by the team from selection to installation was fantastic. System is working well and keeping us nice and cool. I would highly recommend.
Arthur Cowell
Arthur Cowell
Kurt Obermeit
The boys arrived on time, got stuck into it straight away. They were very professional and careful and thoroughly cleaned up after....
Kurt Obermeit
The boys arrived on time, got stuck into it straight away. They were very professional and careful and thoroughly cleaned up after. The install looks flawless and the airflow circulation is amazing! Summer is going to be awesome this year 🙌
Kurt Obermeit
Kurt Obermeit
Adam Collins
Had to pleasure of Benji and the team install a Panasonic ducted system into our property. The professionalism and work quality was top notch. The ...
Adam Collins
Had to pleasure of Benji and the team install a Panasonic ducted system into our property. The professionalism and work quality was top notch. The system is working well and the place was tidy after they left! Highly recommend the team.
Adam Collins
Adam Collins
Stewart Bielby
Very happy with the process from start to finish. Amanda kept us up-to-date with excellent communication and a friendly and helpful attitude. Jack and his ...
Stewart Bielby
Very happy with the process from start to finish. Amanda kept us up-to-date with excellent communication and a friendly and helpful attitude. Jack and his team provided great service during the installation, very tidy and professional. Enjoying the comfort of our new ducted system. Highly recommend this great company!
Stewart Bielby
Stewart Bielby
Amelia Eyers
Benji and team were incredible installing our new air-conditioner. Very professional, punctual and thorough. Explained everything they did with great detail. And left our home ...
Amelia Eyers
Benji and team were incredible installing our new air-conditioner. Very professional, punctual and thorough. Explained everything they did with great detail. And left our home clean, we'd highly recommend Smarter Air.
Amelia Eyers
Amelia Eyers
Matt Coutts
I recently had the pleasure of working with Smarter Air & Electrical for the installation of a Panasonic ducted-air unit in my home. From start ...
Matt Coutts
I recently had the pleasure of working with Smarter Air & Electrical for the installation of a Panasonic ducted-air unit in my home. From start to finish, the experience was nothing short of exceptional. Benji & the team demonstrated a high level of professionalism throughout the entire process. They were punctual, courteous, and clearly knowledgeable about their work. It's refreshing to see a team so committed to delivering top-notch service. The installation process was handled with meticulous care. The team ensured every aspect of the installation was completed to the highest standard. Their attention to detail was evident, leaving me confident that the unit would function optimally. One of the standout aspects of their service was their commitment to cleanliness. After completing the job, the team thoroughly cleaned up the work area, leaving no trace of the installation process. It's these small touches that truly set them apart. I couldn't be happier with the service provided by Smarter Air & Electrical. The Panasonic ducted-air unit works perfectly, and the entire experience was hassle-free. I highly recommend Smarter Air & Electrical, with Benji and the team, for anyone in need of professional and reliable air & electrical services.
Matt Coutts
Matt Coutts

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