Types of air conditioning explained: which one is cheapest to run?

Split, ducted, reverse cycle, evaporative. With so many terms used to describe air conditioning, working out which system suits your home can quickly become confusing.

Running costs make the decision even trickier. A split system cooling one room and a ducted system cooling most of a house aren’t doing the same job, so comparing electricity use alone doesn’t give you the full picture.

We’ll explain how the main air conditioning systems work, where each one makes sense and what really determines which option is cheaper to run.

Air conditioning terms can get confusing because they don’t all describe the same part of a system. Split and ducted generally describe how conditioned air is delivered, while reverse cycle describes whether a system can both heat and cool. Inverter refers to how the compressor operates.

Understanding the difference makes it much easier to compare air conditioning systems fairly.

What does a split system mean?

A split system has an indoor unit and an outdoor unit connected together. It usually conditions one room or a defined area, although multi-split systems can connect several indoor units to a single outdoor unit.

What does ducted mean?

A ducted air conditioning system uses a central unit to distribute conditioned air through ducts and vents around the home. Depending on the setup, zoning can allow different areas to be controlled separately.

What does reverse cycle mean?

Reverse cycle air conditioning can both cool and heat your home. A split system can be reverse cycle, and ducted air conditioning can also use reverse cycle technology, so it isn't a separate system layout.

What does inverter mean?

Inverter technology allows an air conditioner to adjust its output as conditions change, rather than simply operating at full capacity and repeatedly switching off. This can help the system maintain a more consistent indoor temperature while managing energy use.

Both can provide efficient heating and cooling, but the better fit depends on how many rooms you want to condition, how you use your home and the level of control you want.

A ducted air conditioning system can use more electricity than a single split system, particularly when it is heating or cooling several rooms at once. But that doesn’t necessarily mean ducted air conditioning is less efficient. The two systems may simply be doing very different jobs.

A split system might only condition one bedroom or living area, while a ducted system can distribute conditioned air through a network of ducts across much of the home. Comparing their total electricity use without considering the area covered can therefore be misleading.

Several factors affect how much electricity a ducted system uses:

• Zoning: Closing unused zones can reduce the area the system needs to condition.
• System size: An appropriately sized system can operate more effectively than one poorly matched to the home.
• Ductwork: Well-designed and insulated ducts help minimise unwanted heating or cooling losses.
• Temperature settings: Asking the system to maintain a large difference between indoor and outdoor temperatures can increase energy use.
• Home efficiency: Insulation, glazing, shading and air leakage all affect how hard the system needs to work.

So, when comparing the running costs of ducted air conditioning with a split system, look beyond total electricity consumption. Consider how many rooms you actually want to heat or cool and how efficiently each option can provide that level of comfort.

The right air conditioner depends on more than which system is cheapest to run. Think about how many rooms you regularly use, whether you want heating and cooling, your home’s layout and how much control you want over individual areas. A split system may make sense for one or two frequently used spaces, while ducted air conditioning can be more practical when you regularly condition several rooms.

Your local climate, insulation, available installation space and the capacity your home requires also matter. Comparing these factors alongside the upfront cost and expected running cost can help you choose a system that suits how you actually live, rather than simply choosing the option with the lowest advertised energy use.

Is ducted aircon more expensive to run?

It can be. A ducted system may condition several rooms at once, while a single split system generally serves one area. Running costs depend on factors such as system size, efficiency, zoning, temperature settings and how much of the home you condition.

Is ducted aircon more efficient than a split system?

Neither is automatically more efficient in every home. Split systems can be efficient for individual rooms, while ducted systems can suit households that regularly heat or cool multiple areas. The system’s energy rating, sizing and usage all affect efficiency.

Can split systems cool a whole house?

They can cool multiple areas if several units are installed, but whether that makes sense depends on the home. For households that regularly condition many rooms, it can be worth comparing multiple split systems to a ducted system.

Is reverse cycle different from a split system?

Yes, but the terms describe different things. A split system refers to the indoor and outdoor unit configuration, while reverse cycle means the air conditioner can both heat and cool. Many split systems are therefore also reverse cycle.

Is a window air conditioner cheaper than a split system?

A window unit may have a lower upfront cost in some cases, but that doesn’t automatically make it cheaper to run. Capacity, energy efficiency, room size and usage should all be considered when comparing ongoing costs.

Does zoning reduce ducted running costs?

Zoning can help manage energy use by allowing a suitable ducted system to condition selected areas rather than the entire home at once. The actual savings will depend on the system, zoning setup and how your household uses it.

The cheapest air conditioner to run isn’t necessarily the same for every home. A split system can make sense when you mainly condition one or two rooms, while ducted air conditioning may better suit households that regularly heat or cool several areas. System size, efficiency, zoning, insulation and everyday usage all influence the final running cost.

Rather than comparing electricity use in isolation, consider what you actually need the system to do. Choosing an air conditioner that matches your home and how you use it can help you balance comfort, control, and ongoing energy use.