split system air conditioning unit

When choosing an air conditioner, you should not just focus on the cost and brand. There are many other important factors to consider, including the size. When talking about the size, it does not pertain to the actual size of the unit itself. Instead, it is regarding the cooling capacity of the appliance, which is measured in wattage, specifically kilowatts (kW). This cooling capacity concerns the size of the area where the unit will be used.

Therefore, whether you select a window-type, central air, or split-type, you can take advantage of the efficiency of the unit. This guide is about how to determine the capacity of the air conditioner with regards to the room size.

Why Calculating the Right Size of Air Conditioner is Important

It can be tempting to buy an AC that meets just your budget and fits your space. Some homeowners even go for the largest capacity they can afford. However, the correct approach is to purchase according to the size of the room. Air conditioning units that come with large cooling capacities will undoubtedly use more energy. If you do not need a lot, you end up wasting this energy, and you pay higher bills as well.

Similarly, when you buy a small unit, it will not provide the cooling benefits you need for your room. So, how do you know the best size of the air conditioner?

No matter what type of AC you have, you should always look at the wattage. This statement is true if you want to buy a split-type aircon for your space. Generally, you will have to use about 0.142 kilowatts for every square metre of your room.

Let us have some examples:

  • If you have a small room, which is about 18 square metres, your AC wattage should be around 2.5kW to provide you with a cool and comfortable space.
  • Meanwhile, if the room is about 60 square metres, your split-type air conditioner should deliver about 8.5kW of power.

Too low wattage can lead to inefficient operations since you cannot lower the temperature properly.

Tips for Measuring the Space to be Cooled

The most vital piece of information that you should have ready is the exact size of your room. Yes, it will involve a little bit of mathematical equation. But no, you do not have to be a mathematician to know the answer.

Here is how you do it:

  • Get the measurements (in metres) of the room, specifically its width and length.
  • The numbers you have should be multiplied with each other. The result is in square metres.
  • You can also consider adding the ceiling height, especially if it is particularly high. However, for simplicity’s sake, we will just focus on the floor space.

It is typically easy to get the measurements of a room if it is shaped the traditional way – a square. However, if you have a triangle-shaped room or other unusual shapes, it can become a little bit tricky.

Nevertheless, here are some formulas to bear in mind:

  • For triangle-shaped rooms, use the formula Length x Width x ½
  • For odd-shaped spaces with several corners, you need to get all the measurements from one point to another first. Then, you should be able to break the room into smaller measurements to calculate the square metre of the pieces. The same rule applies where you multiply the length by the width. Finally, you will add all the numbers for each piece to get the total square metre measurement.

Thankfully, most rooms in Australia are shaped square so that you can calculate the dimensions easily.

All types of air conditioners, including split-type, are grouped based on their output. As a starting point, you will require one kW cooling capacity up to 1.5kW for every 10 square metres of space.

Each home is different, though. Therefore, your cooling requirements may differ from your neighbour’s. One huge factor to consider is your home’s insulation. If it is well-insulated, you will usually only need the minimum capacity mentioned. However, if your house is uninsulated or poorly insulated and you are located in Perth or any hotter areas, you have to go with a more powerful air conditioner. This way, you can truly enjoy efficient cooling.

installing split system air conditioning

What Size is Perfect for Your Home?

After you have measured the space and you have the measurement in square metres, you can decide how much capacity to go with. Below, you will find a rough guide on how to determine the correct size of the air conditioner to use for your home.

  1. What size of a split system to use for 50 square metres

    Many homes in Perth and other areas in Western Australia measure 50 square metres. Usually, they have a large lounge and designed with open flooring. Small shops and offices also are typically in the 45 to 50-square metre range. In this case, the best capacity is seven to eight kW.

  2. Smaller rooms measuring 10 square metres

    For bedrooms, small kitchens, and lounges that are 10 square metres, a 2.6kW air conditioning unit will suit them. Small offices of the same size up to 20 square metres can benefit from this AC unit capacity as well.

  3. Rooms approximately 20 to 30 square metres

    For rooms that are a bit larger or come with en-suites or a study, the best range is 3.5kW. These areas also include small lounges and mid-sized kitchens. If you have a small room and it has a high ceiling, you may want to choose this cooling capacity of the aircon unit.

  4. Rooms measuring 30 to 45 square metres

    If you have large bedrooms with en-suites, a mid-size lounge, or an expansive kitchen, it is recommended that you go with a five to six-kilowatt appliance. This capacity is also beneficial for those with medium-sized rooms, but the ceilings are higher than normal.

  5. Rooms with 65 square metres of space

    For large spaces, sticking to a seven to eight-kilowatt range can make living more comfortable.

Please note that these numbers are simply guidelines. Some aspects of your property, including how your room was built or its layout, can affect the required wattage.

As always you should speak to an air conditioning specialist if you are looking to install a system in your home. ACSIS Airconditioning Warehouse is here to help, get in touch today.

Author: Ian Grossmith

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