How to Choose the Right Air
Conditioner Size for Your Space
Air conditioning is more than just a luxury in most Australian homes, it’s a necessity for staying comfortable through sweltering summers. Choosing the right system starts with one crucial step: finding the perfect size. A unit that’s too large will waste energy, while one that’s too small will overwork itself and wear out fast. Getting it wrong can lead to costly headaches, so it’s worth making the right choice from the start.
In this guide, we’ll simplify the process of understanding air conditioner capacity. You’ll learn about key measurements, how to calculate the ideal size for your home, and expert tips to help you choose the perfect system.
Air Conditioner Capacity Room Size Guide
Note: This information should be used as a guide only. There are many variables that will affect the requirements of your air conditioning, such as orientation, usage, dimensions, construction materials, insulation, equipment, heat loads, etc.
|
Air Conditioner Capacity |
Room Size Guide* |
Ideal for... |
|---|---|---|
|
2.5kW |
9 - 24sqm |
Small bedrooms and home offices |
| 3.5kW |
25 - 33sqm |
Medium size bedrooms |
|
5.0kW |
34 - 47sqm |
Large bedrooms and medium living spaces |
|
7.0kW |
48 - 65sqm |
Large living spaces |
| 8.0kW |
66 - 82sqm |
Open plan living spaces |
Why Air Conditioner Size Matters
Selecting the right air conditioner for your room size is essential for comfort, efficiency, and long-term cost savings. An incorrectly sized unit can lead to performance issues, higher energy costs, and potential breakdowns.
What Happens If Your Air Conditioner Is Too Small?
A unit that’s too small can struggle to heat or cool your space effectively. It may run longer and work harder, leading to:
● Excess energy consumption
● High electricity bills
● Premature wear and tear
● Poor temperature control
What If Your Air Conditioner Is Too Large?
Bigger isn’t always better. An oversized air conditioner will cycle on and off too frequently in a smaller room, which can cause:
● Uneven temperatures
● Increase in humidity
● Wasted energy
● Noise and frequent breakdowns
Benefits of Choosing the Right Size
A correctly sized air conditioner ensures consistent temperatures, efficient performance, and long-term reliability. It heats and cools your space evenly, reduces energy use, and lowers electricity bills. With less strain on the system, it can last longer and requires fewer repairs. It also maintains balanced humidity, keeping your home comfortable year-round.
Optimise Comfort and Efficiency
For the best results, choose an air conditioner that fits your room size while considering insulation, windows, and sunlight exposure. The right unit delivers comfort, cuts energy costs, and minimises maintenance, potentially saving you money over time.
How to Calculate the Right AC Size
Choosing the right air conditioner size involves more than just measuring your walls. To ensure your AC performs efficiently and keeps your space comfortable, you need to calculate the heating and cooling load—the amount of energy required to maintain a consistent indoor temperature. Several factors impact this load, from room dimensions to insulation and even the local climate.
Understanding Heating and Cooling Load
The heating and cooling load measures how much heat energy must be added or removed from your space to maintain a set temperature. A proper load calculation ensures you select an AC unit that isn’t overworked or underperforming, which can lead to energy efficiency, low electricity bills, and consistent comfort.
Measurements
You can take many of these measurements yourself with a tape measure. A helping hand could be useful for more difficult measurements that require getting into high spaces, like ceiling corners.
● Width and length of walls
● Ceiling height
● Total volume of the space, using wall measurements
● Total area of all walls in square metres
Room Features
Most of these measurements, and figuring out room directions, can be done fairly easily with a tape measure and a compass (either a physical one or digital). For information about your window types, inspect your windows to see what type or glazing or insulation they might have.
● Number of windows
● Window types, including build and glazing details
● Total window area in square metres
● Which direction each windows faces
Build Information
The materials and insulation in your home significantly impact its thermal efficiency. To get accurate details:
● Roof insulation type
● Roof material
● Wall material
● Floor insulation and material type
Tip: If you're unsure about construction details, contact your builder, real estate agent, strata, or a home inspector.
Other Details
This information is easy to obtain - you just need to consider the climate of your city, town, or region. Home shading can also play a role here, so look for any areas of your home that are shaded by trees, buildings, or anything else blocking the sun.
● Number of usual occupants
●Your home’s climate type and location
● Shading
Providing your technician with this information, or using Fair Air online calculator yourself, will give you a more precise understanding of your room’s AC capacity.
Other Factors to Consider
Energy Efficiency Standards
It’s important to choose an air conditioner that is energy efficient, as less efficient appliances can add significant costs to your electricity bill. Luckily, there are a few standards that show which appliances are more eco-friendly.
EER
Stands for Energy Efficiency Ratio, and it describes how efficient an appliance is at a fixed temperature on a yearly basis. A higher EER can be a sign that a unit is more efficient than comparable AC systems.
SEER
Stands for Seasonal Energy Efficiency Ratio, and rates how efficient an AC system is during peak use months, like summer. This can be a more accurate predictor of efficiency than an appliance’s EER.
Energy Star Rating
Uses a star system to rate the efficiency of an appliance compared to other similar models. Units above 5 stars are considered high efficiency appliances.
Zoned Energy Rating
Shows the energy efficiency of an AC depending on your climate zone. Some states now require this label on all new air conditioners.
Climate
Where you live can have a significant impact on the performance of your air conditioner. Australian weather and climate varies a lot across the country, from dry deserts to humid rainforests, so it’s important to take into account how the weather outside your home will affect your AC unit.
A humid climate can have a significant impact on the type of AC you need. Many air conditioners also act as dehumidifiers, so an AC that isn’t powerful enough to handle your home’s humidity may break down. Plus, dehumidifying works best when air cons complete full cycles - if you choose an AC unit that is too large for your space, and it runs shorter cycles to accommodate this, that could mean that your AC won’t actually pull much moisture from the air. Whether too large or too small, the wrong AC in the wrong climate could leave home feeling uncomfortable.
Location and Orientation
Another factor that impacts capacity is how much sun and shade your home gets. If your house or apartment is shaded by trees or other buildings, your air conditioner will not need to contend with as much direct sunlight. Likewise, if your windows face south or east, you will have less heat and light streaming into your home. Before installing an air con system, it’s worth considering insulating your home first, to see if this can help better regulate the temperature inside.
Extra Rooms and Occupants
It’s also worth considering how many rooms in your home need to be air conditioned, as more rooms could impact which type of air conditioner is best for you. Also, think about how many people are in your home on a regular basis - the more occupants you have, the more AC capacity you will need to keep up.
Choosing the Right AC Type
Split Systems
Split air conditioning systems consist of a single indoor unit connected to an outdoor condenser unit, or multiple indoor units connected to an outdoor condenser unit. These units can therefore work in a range of rooms, including larger open-plan living and dining spaces.
Split system air cons are efficient and largely affordable, and when compared to other larger AC systems, they are easy to install and maintain.
Click here to learn more about different types of split systems
Ducted Air Conditioner Systems
Ducted air conditioners use a central unit which processes air and distributes it to rooms in your home via a series of ducts. This type of Central ACs have large capacities, and can heat and cool different zones individually, which makes them ideal for very large or multi-storey homes.
Ducted AC is a great choice for whole home heating and cooling, as well as air filtering and zone control. While these systems are energy efficient, they require a lot more maintenance and a complex installation process.
Window Units
Window air conditioners are another small capacity AC system and, like portable ACs, are usually only available in models up to 6kWh. Window units are installed in a window, which means they don’t need to be vented through a wall.
Window ACs are another good option for apartments. However, window ACs do take up a window, can make more noise than other AC types, and like portable ACs, are often less energy efficient.
Portable ACs
Portable air conditioners are small capacity units that can be easily installed in almost any room with a free window. They tend to have a capacity of less than 6kWh, so work best in a single enclosed room, like a bedroom or a small lounge room.
Portable air conditioners are easier and cheaper to install, and are a great solution for renters or anyone who can’t install a more invasive AC system. However, their limited capacity means they can only work in small spaces. They also have less cycle options, and are less energy efficient.
Conclusion
Choosing the right air conditioner can be challenging with factors like room size, home construction, window placement, and climate to consider. Accurate measurements help ensure you select the right unit for your needs.
If you need extra guidance, consult a professional. If you're considering a Samsung AC, a qualified technician can recommend the ideal system for your space.
