An aging or underperforming air conditioner leaves you and your family feeling uncomfortable. Not only that, but it can send your energy bills soaring and fail when you need it most.
Replacing an inefficient unit ensures you stay cool for the hotter months. You get better reliability, lower running costs, and a comfortable home environment.
This guide walks you through everything you need to know when choosing a new, energy-efficient air conditioner. We’ll cover how to size your system correctly, understand efficiency ratings, compare speed or stage options, and more.
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A properly sized air conditioning unit with the correct cooling capacity is critical to your long-term comfort and energy savings.
Why Correct Sizing Matters
Choosing the right-sized air conditioner is essential for comfort and efficiency.
- Too large: An oversized unit will cool your home too quickly, causing short cycling (frequent starts and stops), which wastes energy, provides poor dehumidification, and can leave rooms feeling clammy or unevenly cooled.
- Too small: An undersized air conditioning system will struggle to cool your room to the set temperature, run for long periods, and increase your electricity bills without properly cooling your space.
How Expert Technicians Determine Size
Professional installers don’t rely on guesswork. They use an industry-standard calculation method outlined in the National Construction Code.
This accounts for insulation levels, window types, orientation, ceiling height, and local climate conditions.
Here’s a basic rundown of what the pros consider:
- The region (climate area) you’re located in
- The dimensions of the room to be air conditioned: length (m), width (m), height (m)
- The total area (m2) of ceiling, floor, external walls, external glazing (windows and doors) and internal walls (separating walls/doors) to other rooms or areas that are not included in the air-conditioned room
- The type of construction of the main building elements: roof/ceiling, floor, internal and external walls, including whether they have been insulated or not
- The type of any glazed windows and doors, the orientation of the glazed areas (the compass direction they face), and the extent of any shading that applies to the glass, such as permanent overhangs and awnings or internal blinds and curtains
- The number of occupants in the room and the type of room usage (either a living room or a bedroom, etc.)
Quick Air Conditioner Size Reference Guide
Here’s a general guide to give you an idea of common AC unit sizes:
| Home Size (m²) | Unit Size (kW) | Cooling Capacity (kW) |
| 112 m² | 7.0 kW | 7.0 kW |
| 167 m² | 8.8–10.5 kW | 8.8–10.5 kW |
| 223 m² | 14.1 kW | 14.1 kW |
| 279 m² | 17.6 kW | 17.6 kW |
Note: Treat this table as a guide only. Always consult a qualified dealer or installer to verify your system size. Experts can explain any differences between their calculations and rough estimates, ensuring your new air conditioner performs efficiently and reliably.
What SEER, Energy Rating Labels, and MEPS Mean (Energy Efficiency in Australia)
SEER: Seasonal Energy Efficiency Ratio
In Australia, SEER measures how efficiently an air conditioner operates across an entire cooling season. A higher SEER means the system delivers more cooling output for every unit of electricity it uses.
This is particularly useful for comparing models under real-world seasonal conditions, rather than just peak performance.
Energy Rating Labels
The star-rating label you see on new air conditioners provides a quick visual guide to energy efficiency. The more stars on the label, the less energy the system uses to provide the same level of cooling or heating.
Checking the Energy Rating Label helps homeowners quickly narrow down efficient options without knowing technical specifications.
MEPS: Minimum Energy Performance Standards
MEPS set the lowest acceptable efficiency level for air conditioners sold in Australia. These standards ensure all units on the market meet a base level of performance and energy savings.
MEPS are regularly updated by the government to encourage manufacturers to continually improve efficiency.
Why These Ratings Matter
Understanding SEER, Energy Rating Labels, and MEPS helps you compare units. You can choose one that balances performance and long-term energy savings.
Selecting a high-efficiency air conditioner not only reduces your electricity bills but also lessens your environmental impact, especially important in Brisbane’s hot and humid climate, where systems may run heavily during the hotter months.
Single-Stage Units: One On/Off Speed
Single-stage air conditioners operate at full capacity or not at all. They’re usually the most affordable to buy and install, making them a budget-friendly choice.
However, because they only run at one speed, they can create noticeable temperature swings and may use more energy overall. This stop-start operation can also cause more wear on components over time.
Multi-Speed Units: A Few Set Speeds
Multi-speed systems offer two or three fixed speeds. They can run at lower speeds when less cooling is needed, resulting in an even temperature and improved energy efficiency.
They’re typically more expensive upfront but offer better comfort and can reduce your energy bills in the long term.
Variable-Speed (Inverter) Units: Continuous Modulation
Variable-speed (or inverter) air conditioners adjust their output continuously to match the exact cooling or heating demand. This creates consistent indoor temperatures, reduces humidity, and is the most energy-efficient option.
They’re also quieter, and avoiding harsh stop-start cycles can extend the lifespan of the system. The main downside is the higher initial purchase and installation cost.
Energy and Comfort Trade-Offs
The more stages or speed options a system has, the more efficiently it can operate. Variable-speed and multi-speed units offer smoother temperature control, quieter operation, and reduced energy use compared to single-stage systems.
While single-stage models may be cheaper upfront, they generally cost more to run.
How to Decide Which Stage/Speed Fits Your Needs and Climate
In warmer and humid regions such as Brisbane, where air conditioners run for longer periods, variable-speed or multi-speed units can offer significant energy savings and comfort. Always consult a licensed professional to match your system to your home’s size, insulation, and local climate.
Why Refrigerant Matters (GWP, Regulations, Availability)
The refrigerant inside your air conditioner affects both its environmental impact and long-term servicing costs. Australia follows the Kigali Amendment to the Montreal Protocol, which sets a national phase-down of hydrofluorocarbons (HFCs) due to their high Global Warming Potential (GWP). Choosing a refrigerant with a lower GWP helps reduce greenhouse gas emissions and aligns with future regulations. Availability also matters, as older refrigerants are phased out, prices for servicing may rise.
R-410A: Legacy Refrigerant
R-410A has been the standard HFC refrigerant for split systems and ducted units across Australia for many years. While it’s reliable and widely supported today, its high GWP means it’s gradually being phased down under the Australian HFC phase-down program. Over the next decade, supplies will become more limited, and servicing costs for R-410A systems may increase.
R-454B: Newer Lower-GWP Refrigerant Option
R-454B is emerging as a preferred replacement for R-410A. It offers a GWP that’s around 78% lower than R-410A, making it more environmentally friendly and compliant with future efficiency and emissions standards. Many new air conditioner models released in Australia are starting to use R-454B, ensuring easier access to refrigerant supplies and reduced long-term environmental impact.
Practical Guidance for Homeowners
If your current air conditioner uses R-410A, you don’t need to replace it immediately. It’s still legal to use and service. But as supplies tighten, topping up refrigerant or repairing leaks could become more expensive.
If you’re installing a new system or planning a major upgrade, choosing an R-454B unit is a future-proof option. It aligns with Australia’s HFC reduction targets, lowers your household’s carbon footprint, and helps avoid higher servicing costs down the track.
Hewitt Trade Services is the best in the air conditioning business in the Brisbane area. We have installed, repaired and serviced thousands of units during 21+ years of business.
Our years of experience give us a laser focus on the most common air conditioning challenges in the Brisbane community. We are highly trained, reliable, professional, efficient and fast.
Our 4.8-star rating from over 330 reviews on Google proves it.
We can help you assess your needs, get a quote, and make informed decisions about servicing your air conditioner. Using a reputable company like Hewitt Trade Services ensures a smooth and satisfactory experience. You can enjoy the benefits of a reliable and efficient air conditioner for years to come.
Are you ready to make an informed decision about your air conditioner maintenance?
We service the following areas in Brisbane:
Air Conditioning Albion – Air Conditioning Amberly – Air Conditioning Annerley – Air Conditioning Anstead – Air Conditioning Ascot – Air Conditioning Ashgrove – Air Conditioning Aspley – Air Conditioning Augustine Heights – Air Conditioning Bellbowrie – Air Conditioning Boondall – Air Conditioning Booval – Air Conditioning Bowen Hills – Air Conditioning Bracken Ridge – Air Conditioning Bridgeman Downs –Air Conditioning Brisbane – Air Conditioning Brookfield – Air Conditioning Brookside Centre – Air Conditioning Brookwater – Air Conditioning Carole Park – Air Conditioning Carseldine – Air Conditioning Chapel Hill – Air Conditioning Chermside – Air Conditioning Clayfield – Air Conditioning Collingwood Park – Air Conditioning Enoggera – Air Conditioning Everton Park, Air Conditioning Fig Tree Pocket – Air Conditioning Forest Lake – Air Conditioning Gaythorne – Air Conditioning Geebung – Air Conditioning Gordon Park – Air Conditioning Hamilton – Air Conditioning Hendra – Air Conditioning Indooroopilly
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