What Size Ducted Aircon Do I Need

Phill Crawley

Smarter Air & Electrical

i 3 Contents

Ducted Aircon Sizing

What Size Ducted Aircon Do I Need? Ducted Air conditioners are great at keeping us comfortable year round in Queensland. But before you buy a new ducted air conditioning system, make sure you know what size unit is needed. The size of your air conditioner will depend on a variety of factors such as the size of your home, the amount of space that needs to be cooled & how well your home is insulated. You should make sure to measure your house carefully before you buy a ducted air conditioner!

Calculate the size of your home

A good general guide to determining what size ducted aircon you need is using the watts per square meter method; this is what the majority of size calculators are based on. To do this first, determine the floor area of your home. To calculate the area of your home you simply multiply with room length by the room width. For example:

Bedroom 1
Room length X room width = X square meters
3m X 3m = 9 square meters

Do this calculation for every room in your home including common areas such as hallways etc. You can leave out any rooms that don’t require air conditioning such as bathrooms , laundries & cupboards.

Once you have the area of each room, add them all together. For Example:

Bedroom 1 = 9 square meters
Bedroom 2 = 8 square meters
Bedroom 3 = 8 square meters
Bedroom 4 = 8 square meters
Kitchen/Dining = 30 square meters
Living = 28 square meters

Total Area = 91 square meters

Now we have the total square meters we can move onto the next step to determine the correct size! Make sure to measure your house carefully before you purchase an air conditioner!

Determine the required cooling capacity for your ducted air conditioner

Now that we know how many square meters we need to cool we simply multiply by 0.16kW, this number is a general rule of thumb recommended for Brisbane & Gold Coast homes. For Example:

91 square meters X 0.16kW = 14.56kW Total Cooling Capacity

So to cool this entire space we require an air conditioner with at least 14.56kW cooling capacity! 

Now you have to think about how much of this space you would like to cool at the same time (coverage) to get to your final required cooling capacity. 

It’s rare to size a ducted air conditioner to cool 100% of the home at any one time as this will result in a larger unit which will have higher airflow rates that will be difficult to manage when you are trying to cool only a few rooms in the home. 

The sweet spot for coverage is around 70%, in other words we want to size the air conditioner so it has the power to cool at least 70% of the home at once. To calculate this simply take your total required cooling capacity and multiply by 0.7. For Example:

14.56kW Total Cooling Capacity X 0.7 = 10.19kW

So there we have it, we need a ducted air conditioner unit that has a rated cooling capacity of at least 10.19kW to cool up to 70% of the home at one time.

Air conditioners have at least three capacity in their specifications:

  • Min cooling capacity – This is the minimum cooling capacity the unit can achieve, the lower this number the more efficient your unit will be when cooling your bedrooms at night when there is little heat load reducing your electric bill.
  • Rated cooling capacity – This is the unit’s tested capacity and is usually most efficient when running at this capacity. We use this value when determining unit size.
  • Max cooling capacity – As the name suggests this is the maximum capacity, the higher the value the better chance your air conditioner has at coping with extreme heat waves.

Assess how well your home is insulated!

The method of sizing an air conditioner shown above is a general guide rather than an exact science, an air conditioning professional will take into account many factors such as:

  • Ceiling Height
  • Windows
  • Blinds & Curtains
  • House Design
  • Insulation
  • Roof Ventilation
  • Tightness of the home
  • Local Climate
  • Orientation
  • Your lifestyle
  • Desired Temperature

If using our method above to size your air conditioner it’s best to make sure your home is well insulated & ventilated, speak to your home comfort specialists to get a quote on adding ceiling insulation and solar powered roof ventilators to reduce the load on your soon to be installed air conditioner!

What size ducted aircon do you need?

Selecting what size ducted aircon you need is important because it will affect both the energy efficiency & performance of your system. What if your ducted air conditioning system is undersized or oversized?

  • Undersized air conditioners will not have adequate capacity to cool your home resulting in the unit running at its maximum capacity at all times increasing your energy bill.
  • Oversized air conditioners may short cycle, this results in the air con unit running for a brief period of time before reaching the desired temperature and shutting off. Oversized ducted systems will struggle to maintain the correct temperature and will not run for long enough to remove humidity from your home.

A correctly sized ducted inverter air conditioner will regulate it’s capacity between the min & max capacity to provide a consistent temperature through the home whilst doing a good job at maintaining indoor humidity between 30-50%.

Conclusion

Using the methods described above to size your air conditioner is a good way to get an idea of what size system you should consider for your home. Before making a purchase we recommend talking to your ducted air conditioning installation specialist, they have specialist software tools such as Plandroid for ducted air conditioning system design to properly confirm which size system is correct for your home. Contact our friendly team today on (07) 3067 2396 to help you choose the best solution for your home

Ducted Aircon Sizing

Jason Warren
Benji and his team of guys were the most polite, professional and knowledgeable service that we have received. They were on time and the work ...
Jason Warren
Benji and his team of guys were the most polite, professional and knowledgeable service that we have received. They were on time and the work preformed was faultless even to the vacuuming and cleaning at the end. I can not recommend Smarter air and Electrical enough including the initial quote we received and Amanda with her organising and communication. All first class
Jason Warren
Jason Warren
Nicola Alison
10 star review to the team at SmarterAir & Electrical have the WOW factor. Brilliant from start to finish. Having a Property Manager...
Nicola Alison
10 star review to the team at SmarterAir & Electrical have the WOW factor. Brilliant from start to finish. Having a Property Manager background and high standards I know quality service and you were fantastic! The Neo Panasonic unit ducted system is so quiet it’s a dream unit. Don’t even know it is on! Sensors in each room and can remotely turn the system off via the MyPlace app. Specialists in what you do and don’t outsource the annual service shows your genuine accountability “Thank you so much” to all involved, Alex, Davis, Amanda & Chris. Today the installation & electrical team, professional and friendly, Tom, Jake, Eden, Levi, Nav and Will were simply brilliant a Very big Thank you for making my day! They even vacuumed my house and cleaned up & used drop sheets when installing they really looked after my property. I will be adding lights and the garage door to the future to the MyPlace app and also will be upgrading my residential smoke alarms with them. I am a client for life and will recommend you to everyone. Nothing is too much trouble. I chose well and grateful for all of the answers to my questions. It takes a lot to WoW me these days, but you did, thank you for all your hard work.
Nicola Alison
Nicola Alison
Temnit Teshager
I had smart air & electrical for air conditioning service install a new unit and I couldn't be happier with the experience. From scheduling the ...
Temnit Teshager
I had smart air & electrical for air conditioning service install a new unit and I couldn't be happier with the experience. From scheduling the appointment to the completion of the job, everything was seamless. The technician arrived promptly, was courteous, and thoroughly explained the work that needed to be done. They also provided helpful tips for maintaining the unit in the future and cleaned the house after finishing the job.The pricing was fair, and the service was top-notch. I highly recommend them for all your air conditioning needs!
Temnit Teshager
Temnit Teshager
steve fernandes
Had my Panasonic ducted unit installed in December. They did not try and upsell me a unit that was too big for my house size ,...
steve fernandes
Had my Panasonic ducted unit installed in December. They did not try and upsell me a unit that was too big for my house size ,Other companies recommended 1 -2 (16kw-18kw)sizes bigger. Recommended a 12.5kw which would be sufficient for my home size or could get away with the larger 14kw(summers only getting hotter). Ended up going with a Panasonic 14kw Delux unit with MyAir. On the day all the materials were delivered 30 mins (6.30am) before the guys turned up. Started at 7 am and left by 2 pm, They check with me the location of each room where the ducts were going as I have fans as well. House was vacuumed and marks on the wall cleaned. The electrician stayed back till about 3 ish to finish up, test each zone and run through the MyAir tablet. Easy to deal with, quick responses with emails and calls and happy to work with me as I built a stand so my unit was of the ground. Also went up in the ceiling to finish off some work and the ducting is all tidy. Highly recommend!
steve fernandes
steve fernandes
Saji Joseph
Smarter Air and Electrical recently replaced our ducted Air Conditioning system. The team is very professional and their service from start to finish was excellent. ...
Saji Joseph
Smarter Air and Electrical recently replaced our ducted Air Conditioning system. The team is very professional and their service from start to finish was excellent. I would like to extend our special thanks to Jack, Benji, Jacob and Kesan who did the installation and the commissioning. Also, sincere appreciation to all the pre planning work carried out by Davis, Chris, Alex and Amanda. Everything went smoothly from start to finish. Thanks again.
Saji Joseph
Saji Joseph
Darren Maloney
The Smarter Air & Electrical team has been amazing to work with from start to finish. The team have made the process seamless and we ...
Darren Maloney
The Smarter Air & Electrical team has been amazing to work with from start to finish. The team have made the process seamless and we could not be hapier with the finished product. The process has been so good that we have a freind currently getting a system from the team I only have great things to say about my experience it was easy to send them your way. A big thank you to the team and I'm sure I will send more business your way.
Darren Maloney
Darren Maloney
Matthew Harriott
The guys at Smarter Air and Electrical are great. From the inspection and quote through to the install and after sales service the company is ...
Matthew Harriott
The guys at Smarter Air and Electrical are great. From the inspection and quote through to the install and after sales service the company is outstanding. The install team are professional and clean up after them selves. Once mine was complete, they even came back and did a neighbours as well. Highly recommended.
Matthew Harriott
Matthew Harriott
Dallas Werder
From the first interaction, quoting and installation- Absolute outstanding service. They were always on time, polite, professional, attentive and explained everything perfectly. We could not ...
Dallas Werder
From the first interaction, quoting and installation- Absolute outstanding service. They were always on time, polite, professional, attentive and explained everything perfectly. We could not be happier with our ducted air con. Use this company if you want ducted.
Dallas Werder
Dallas Werder
Sue Cee
Once again, brilliant customer service from start to end. Professional, courteous, explaining the process as they went along, Jacob and Will were great. I 100% recommend ...
Sue Cee
Once again, brilliant customer service from start to end. Professional, courteous, explaining the process as they went along, Jacob and Will were great. I 100% recommend Smarter Air & Electrical
Sue Cee
Sue Cee
Bhavesh Bhatt
The guys at Smarter Air did very good job at installing ducted system in my already built home. Starting from their Sales team to...
Bhavesh Bhatt
The guys at Smarter Air did very good job at installing ducted system in my already built home. Starting from their Sales team to customer rep to Electrician and installation team all were very professional and helpful. Highly recommended 👍🏼
Bhavesh Bhatt
Bhavesh Bhatt

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