Australian weather can be extreme. Winters can be bitingly cold, and summer temperatures continue to reach record levels, making both heating and cooling a necessity for year-round comfort. However, depending on where you live, heating and cooling can account for 20 to 50 per cent of the energy used in your home. Plus, with the rising cost of living, smart decisions are needed to keep things affordable.
So with winter on our doorstep, we thought it timely to ask the question: are split systems expensive to run for heating? And how do they compare to ducted systems?
What are split systems?
A reverse-cycle split system is an indoor, wall-mounted unit that provides both cool and warm air. It is known as “split” because it has units inside and outside the home. The indoor unit provides the “conditioned” air in a home’s space and contains filters, a fan, a heat exchange coil and a remote signal receiver. Often referred to as the “condenser,” the outdoor unit pumps refrigerant to and from the indoor unit. It contains a propeller fan, compressor, heat exchange coil and a circuit board.
What affects the running costs?
There are a range of different variables that determine your split system air conditioner running costs. The most influential factors are:
- The size (capacity) of the unit in kW
- The space/s it is heating or cooling
- If the unit has an inverter
- The temperature the unit is set to
- Your kWh energy costs
- The length of time the system is operating for
- The system’s energy rating
- Whether you regularly have it serviced
- Other energy-saving elements in your home such as insulation, windows, etc.
It’s also important to note that purchasing an air conditioner with a smaller capacity will not necessarily save you money on your power bills. If the area to be cooled is too large compared to the unit’s output, the unit will be forced to operate at full capacity, which puts pressure on the system. A unit with an insufficient output may also not effectively heat or cool the area of your home it needs to.
Are split systems efficient?
Generally, yes. A reverse-cycle air conditioner can reach 300 to 600 per cent efficiency. This means that it can take one unit of thermal energy and turn it into three to six times as much heating (or cooling) energy. If you set your system at 17 to 19 degrees in winter, you can maximise your energy savings.
Every degree higher than this will increase your running costs by five to ten per cent. Systems that include an inverter can reduce running costs further, as once the set temperature has been reached, the unit will use less power to maintain the required temperature.
How much do split systems cost to run?
In terms of calculating split system heating or cooling, several factors influence running costs, including your home’s insulation, floor plan, and the number and size of windows. An air conditioner cost calculator can give you a more detailed picture of how much your system costs to operate based on your usage habits and the size of your system.
However, here are some rough costs for different sized systems based on a standard residential energy tariff in Brisbane, with the air conditioner used over a 12-week period at a temperature of 24 degrees:
- A 2.5 kW system running for four hours a day will cost approximately $40.11 per year or 47.75 cents per day to run.
- A 3.5 kW system running for eight hours a day will cost approximately $134.16 per year or $1.59 per day to run.
- A 3.5 kW system running for four hours a day will cost approximately $67.08 per year or 79 cents per day to run.
- A 5.0k W system running for four hours a day will cost approximately $104.43 per year or $1.24 per day to run.
- A 5.0k W system running for five hours a day will cost approximately $130.33 per year or $1.55 per day to run.
How do they compare to other types of systems?
When weighing up your heating options for split systems, it’s worth comparing them to another popular choice of air conditioning: ducted units.
Ducted air conditioning systems are designed to heat and cool an entire home. They have an outdoor unit and ducting that is usually installed under the floor or in the ceiling. Air ducts run from the outdoor unit, generally through channels in the ceiling, and then into each room.
Ducted systems are a little more expensive to run, but tend to last longer, are much more aesthetically-pleasing, and a highly-desirable addition to a home. Just like split systems, you can use a cost calculator to work out how much you might pay to run one. In terms of rough calculations, if your electricity costs twenty cents per kWh and your unit has a total input of 3kw per kWh at full rated capacity, the cost per hour would be sixty cents. If you run the unit for eight hours at fifty per cent capacity, then the cost per hour would be: 20 x (3 x 50 per cent) = 20 x 1.5 = 30 cents per hour. And the cost for eight hours would be 30 x 8 = $2.40.
However, a few things worth noting are that different rates are often charged for electricity at different times of the day, so you may need to make more than one calculation. A whole-house system also costs the most — from $1.45 to $2.12 per hour, so factor that in if you’re considering installing a ducted unit. Energy rating labels are not compulsory on ducted systems, but you can check their energy efficiency performance on the GEMS Registration Database.
How do I determine the system that’s right for me?
There are pros and cons to both types of air conditioning systems. Split systems are cheaper to install and run, however, they only cover a small area compared to a ducted system, so are best for smaller properties. Ducted systems are more stable in larger houses with multiple levels and rooms because the system’s central unit is designed to avoid excessive wear and tear, and the system isn’t pushed to the limits even during peak hours.
So, in summary, both types of air conditioning systems can do the job, but in different ways. Your choice will depend on the type of property you live in and the extent to which you want to control the temperature in each room. Are you willing to spend more upfront to install a system that will service multiple rooms? Or do you have a smaller property and only need to heat or cool one or two rooms? The choice is yours!
References
- 2021, Energy efficient cooling: do split-systems come out on top? AGL
- 2013, How much does a split system air conditioner cost to run? H&H Air Conditioning
- Tahnee-Jae Lopez-Vito, 2020, How much electricity does my air conditioner use? Canstar Blue
- 2020, Ducted Air Conditioning vs Split System: What is right for me? Global Cool Air
- 2015, How much does ducted air conditioning cost to run? Brisbane Air
- 2018, Air conditioning terminology – the words you need to know, Daikin
