Air Conditioning Calculation Formula | Split System Size Calculator

How can I easily calculate the size of the split system I need?

When it comes to air conditioning installation Brisbane (be it ducted or split system), it’s crucial that you get a “Goldilocks” solution – not too powerful, not too weak, but just right.

And that starts by determining exactly how much cooling power you need.
A system that’s too large will waste power and cool your home too quickly, accelerating wear-and-tear
A system that’s too small will be underpowered, and will struggle to keep you cool during Brisbane’s summer
The ideal system lands right in the middle, and maximises energy- and cost-efficiency

The first thing you’ll need to do before split system installation can begin? Calculate the volume of your room to determine the right size.

Room and air conditioning sizing guide

How powerful does my split system need to be?

Using a formula to calculate how powerful your split system needs to be is a great starting point.

A word to the wise: these are only ballpark figures – for a more accurate assessment of how large your split system air conditioner needs to be, it’s best to talk to a professional and ask for their opinion.

Step 1: calculate the area of the room

The first step towards choosing the most suitable split system for your room is determining how much cooling your room needs.

And that begins with your room area.

Start by calculating the floor area of the room you’re getting a split system air conditioner installed in.

Step 2: multiply the area by the required wattage

Once you have the area of the room, you’ll want to multiply that number by the required wattage needed to deliver powerful cooling for each square metre.

For most homes with 2.4m ceilings, you’ll multiply by 150W, however this will depend on your ceiling height:
2.7m ceilings – 160W
3m ceilings – 170W

This will give you how many watts your split system will need to provide a comfortable level of cooling to your room.

Step 3: convert into kilowatts (kW)

Most air conditioning units are measured in kilowatts (kw), not watts – luckily, it’s pretty easy to convert between them – just move the decimal point 3 places to the left to get the kW value.

For example, 100m² x 150 watts = 15,000 watts, which equals 15 kilowatts – for this room, you’ll need a 15kW split system.

Step 4: get in touch with an air conditioning professional

Now you know how large and powerful your air conditioning unit has to be.

However, this is only a rough outline – how effective your cooling will be is also affected by factors including:
- Room orientation and direction
- Windows
- Insulation quality
In these cases, the most accurate way to find out what you need is to get in touch with a professional.

split-system air conditioning installation in Brisbane

Why you need a professional on your side

There are other factors at play

It’s important for us to know which direction the rooms face.

Southerly facing rooms require less cooling in summer, but more heating in winter. If the room is facing West, or if it faces North and has large windows, we may have to use a factor of 180 watts to compensate.

You may not know about these other variables – however, our team does!

Accounting for usage

It isn’t just room orientation and features that can change the sizing formula – room usage also comes into play.

And we aren’t just talking about appliances, either – if more than two people regularly occupy the room in daylight hours, add an extra 200 watts for each additional person.

Size isn’t everything

While size is important, it isn’t the only thing that matters – in order to give you the best possible value (and ensure your comfort), we need to look further.

The kW rating isn’t the only thing that goes into selecting a split system air conditioner for your home. Different brands and systems come with different features, and use energy at different rates – all of which needs to be considered.

The leading team for split-system air conditioning installation in Brisbane

With 30+ years in the business (and counting), Tri-Tech’s team have provided split-system air conditioning installation for all sorts of properties. We’ve seen it all – there’s nothing that can surprise us anymore.

Not only that, but our skills have been formally recognised too. We’ve won Mitsubishi Electric’s Dealer of the Year award for the south-east Queensland region a whopping ten times – the most recent in 2019.

And it’s all thanks to our: