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Queensland households rely on air conditioning for much of the year, so understanding how different systems affect ongoing power bills is crucial. Many homeowners find themselves comparing ducted air conditioning in Sunshine Coast with a split system but are unsure which option will be more economical once the unit is installed and in daily use. Crown Power Air Conditioning explores how each system performs in various conditions to help readers make a confident decision that suits comfort and budget.
Readers will learn how ducted and split systems differ in energy efficiency, real running costs and long-term value across homes. Homeowners will understand the key cost drivers for each type of system, how those costs are likely to play out on their electricity bills and what to consider when choosing the most cost-effective solution for their property and lifestyle.
Running costs for ducted and split system air conditioning come down to how much electricity the unit uses each hour and how often it runs in the local climate. To compare systems fairly, homeowners need to turn kilowatt (kW) capacities and efficiency ratings on the energy label into dollars on a power bill.
Air conditioning technicians help clients work out costs by combining the system’s power input, the current electricity tariff and realistic usage patterns for a typical home.
The basic calculation is the same for both ducted and split systems:
Energy used (kWh) = Power input (kW) × Hours of operation
Running cost = Energy used (kWh) × Electricity tariff (c/kWh)
For example, if a unit draws 2.5 kW while running and operates for 6 hours:
Daily energy use = 2.5 kW × 6 h = 15 kWh
At 30 cents per kWh, the daily cost = 15 × $0.30 = $4.50
Queensland tariffs vary between retailers and time of day, so experts use the homeowner’s actual rate or a realistic average for comparisons.
Input power depends on how efficient the air conditioner is. Two key ratings are shown on specification sheets:
Cooling or heating capacity (kW) ÷ EER or COP = Power input (kW)
If a ducted system provides 10 kW of cooling with an EER of 3.0:
Power input = 10 ÷ 3.0 = 3.33 kW
If a similar capacity multi-split has an EER of 4.0:
Power input = 10 ÷ 4.0 = 2.5 kW
Even before usage patterns are considered, the split system will cost less per hour to run because it draws less power to produce the same cooling.
The star rating and annual energy consumption figures on the energy label can also be used to estimate yearly running costs by multiplying the kWh figure by the local tariff. However, for homes, technicians often adjust these figures because the standard test conditions may not match local summer heat and humidity.
Ducted systems commonly run for more hours because they cool or heat the whole home at once. Split systems are often used to condition only the main living zone or occupied bedrooms. This changes the total hours and kWh used over a season.
To estimate realistic running costs, experts consider:
For example, if a ducted system cools the entire home for 8 hours on a hot day and a split only cools the living area for 5 hours, the ducted unit will have higher daily kWh use even if both are efficient. Accurate cost comparisons always combine the technical efficiency numbers with how the family will actually run the system.
Homeowners are usually most interested in which system will use less electricity on their actual power bill. In simple terms, a well-designed split system generally uses less energy to cool or heat one or two rooms, while a well-zoned ducted system can be more efficient for whole-home comfort if it is used correctly.
Energy consumption depends on the system size, efficiency rating, zoning and how often it runs in hot, humid conditions. Understanding these factors helps homeowners choose the right type and avoid paying for capacity they do not really use.
A ducted system has one central unit that pushes conditioned air through ducts to multiple rooms. Because it is sized for the whole home, its input power is higher than that of a single split. A typical 14 kW ducted system might draw 3.5 to 5 kW of electrical power when running at or near full capacity.
In a high-set or low-set home, running ducted air conditioning to all rooms for long periods on peak summer days can result in high daily consumption. However, a modern inverter ducted system rarely runs at full output all the time. Once the set temperature is reached, it modulates down so the running power can drop.
Real energy use with ducted systems is heavily influenced by:
If a family regularly cools the whole house in the evening, a ducted system can be more economical per room than installing and running split systems in every space.
Split systems condition only the rooms where indoor units are installed, so their total capacity and input power are lower. A 2.5 kW bedroom split might draw around 0.6 to 0.8 kW at full load, while a 7 kW living area split may draw around 1.8 to 2.3 kW.
For households that only need to cool one or two key areas most of the time, individual splits usually use less total energy than a large ducted system. Each unit can be switched off when a room is empty, avoiding conditioning unused spaces.
However, if there are five or six splits around the home and several are running together for long periods, the combined draw can approach or exceed that of a single well-sized ducted system.
Both ducted and split systems are available with high star ratings and inverter technology. Higher star ratings generally mean lower energy use for the same amount of cooling or heating, so choosing efficient models is critical regardless of type.
In Queensland’s climate, real energy consumption is also shaped by:
For a couple, cooling only a living room and main bedroom, efficient split systems usually minimise energy consumption. For a larger family that often uses most rooms, a properly designed zoned ducted system can deliver better overall efficiency and comfort per kilowatt hour.
Queensland’s hot, humid summers and mild winters have a direct impact on how much it costs to run ducted and split system air conditioning. Because most households use air conditioning heavily for cooling rather than heating, the local climate tends to favour some system types and settings over others in terms of efficiency.
Understanding how heat, humidity and seasonal patterns affect each system helps homeowners choose the option that will be more economical over the year, not just on paper efficiency ratings.
Cooling is required for a large part of the year, especially in coastal regions and the tropics. Ducted systems typically cool the whole home at once, so long cooling seasons can mean high cumulative running hours and higher bills if zoning and temperature settings are not used smartly. Split systems cool only the rooms where they are installed. In a home where people mainly use the living area in the evening and bedrooms at night, multiple high-efficiency splits can cost less to run over the year because unused rooms are not being cooled.
In very hot inland or northern areas where the whole house needs to be comfortable for most of the day, a well-designed ducted system with zoning can be competitive on running costs because it avoids multiple outdoor units and can use larger, more efficient ducted units.
High humidity is a major factor, especially along the coast. Both ducted and split systems use extra energy to remove moisture from the air, not just to reduce temperature. When humidity is high, units run longer at part load, which can raise running costs.
Split systems usually allow targeted dehumidification in occupied rooms. If only bedrooms need to feel dry at night, running bedroom splits on a dry or low fan setting can be cheaper than operating a ducted system that conditions the whole home. On the other hand, modern ducted systems with variable speed compressors can handle humidity efficiently if the ductwork is sealed and correctly sized and if airflow balances are properly set up during installation.
Poorly designed ducted systems with leaky ducts in hot roof spaces are hit twice by the climate. They work harder because of the humidity, and they lose cooled air into the roof, increasing running costs.
Queenslanders often run air conditioning into the evening and overnight during summer. Nighttime use patterns affect which system costs less to run.
For homes where only bedrooms are used after about 9 pm, split systems usually have the advantage because only those rooms are cooled. Homeowners can set slightly higher temperatures at night for further savings. In a ducted home, if zoning is not set up or used correctly, the system may still cool unoccupied zones, adding unnecessary cost.
In winter, most of coastal Queensland requires only modest heating. This shorter heating season means cooling efficiency is far more important than heating performance when comparing running costs. A high-efficiency ducted system, optimised for cooling at local summer design temperatures, typically delivers the best long-term cost outcome in various conditions.
Home size and layout have a major impact on whether ducted or split system air conditioning will be cheaper to run. The same system can perform very differently in a compact unit compared with a sprawling two-storey house, so it is essential to match the design to how the home is built and used.
In general, ducted systems suit larger or multi-level homes where many rooms require cooling, while split systems are often more economical for smaller homes or when only a few key areas are used regularly. Assessing floor area, room layout and usage patterns before selecting a system helps ensure better efficiency and lower long-term operating costs.
In a one- or two-bedroom unit or a compact single-level home, a ducted system can be overkill from a running cost perspective. A correctly sized split system in the main living area, plus a small bedroom unit if needed, usually provides more than enough comfort with lower electricity use.
Because the total volume of air is relatively small, a 2.5 to 7 kW split system can cool the main spaces quickly without running at full capacity for long periods. There is also less ductwork or none at all, so there are fewer efficiency losses. If only one area is used during the day, residents can simply switch off the bedroom unit, avoiding paying to cool the entire home.
In many units, body corporate limitations and restricted roof or ceiling space also favour split systems. Ongoing running costs stay manageable because only rooms in use are cooled and maintenance is simple.
In a medium or large family home with multiple bedrooms and open-plan living areas, running several individual splits can become inefficient. Each indoor unit and outdoor unit draws power, and when four or five systems run at once, the combined usage can approach or exceed that of a single ducted system.
For these homes, a ducted system with zoning often provides better cost control. It can cool large open areas evenly, which is important in high-ceiling or open-plan designs. Zoning allows different parts of the home to be cooled at different times, so the family can focus cooling on living spaces by day and bedrooms at night instead of running every zone all the time.
Two-storey homes or homes with wings and many separate rooms introduce more complexity. Cool air from a single split system in the downstairs living room will not effectively reach upstairs bedrooms, which often become the hottest spaces in summer.
In these situations, ducted systems are usually more economical to run than trying to manage a collection of splits on both levels. Ducts can be routed through roof cavities to supply all upstairs rooms from one efficient outdoor unit. With smart zoning, homeowners can cool only the upstairs sleeping areas at night and reduce or turn off cooling downstairs, which keeps running costs in check.
How a household uses its air conditioning has as much impact on running costs as the choice between ducted and split systems. Zoning and daily usage patterns determine whether cooled air is delivered only where it is needed or wasted on empty rooms. Understanding these patterns helps homeowners decide which system type will be more economical for their lifestyle.
Both ducted and split systems can be energy efficient if they are matched to realistic usage. Families who cool the whole home for long periods often benefit from modern ducted zoning, while households that only cool one or two rooms at a time may find multiple split systems more cost-effective.
Ducted systems use a central unit that feeds cool air through ceiling ducts to different zones. Zoning divides the home into controllable areas such as living zones, bedroom zones or upstairs and downstairs. Smart controllers then allow the user to turn zones on or off and sometimes adjust different temperatures.
In practical terms, this means a family might run only the living room and kitchen zone during the afternoon, then switch to bedroom zones at night. By closing off unused rooms, the ducted system can operate at a lower capacity, so it uses less electricity than if the whole house remained on.
Modern ducted setups can include variable-speed inverter compressors and individual room temperature sensors. In a well-designed system, this allows the unit to ramp up gently during peak heat, then settle into an efficient low-power mode once set temperatures are reached, which helps control running costs on long humid days.
Split systems are inherently zoned because each indoor unit serves a single room or a small open area. This makes them ideal where usage is very localised. For example:
A correctly sized split system only cools the occupied room, which avoids the distribution losses of ducting and can use significantly less energy than a whole-of-home ducted system. For many apartments or compact post-war homes, a single well-positioned split can handle most daily needs with very manageable running costs.
Homes often follow predictable patterns, such as closed-up daytime operation with blinds down during summer work hours, then heavy evening and overnight cooling during hot spells. The most cost-effective setup is the one that aligns with those habits.
For households that like to walk into a uniformly cool home and keep multiple areas conditioned for long stretches, a zoned ducted system can spread the load efficiently. For homes where cooling is used occasionally or concentrated in just one or two spaces, well-planned split systems are usually cheaper to run.
The key is to be realistic about how many rooms are typically occupied at the same time, how long the air conditioning runs on a summer day and whether these patterns are likely to change as the family grows or works from home more often.
For most homes, a single split system is usually cheaper to run day to day than a whole‑of‑home ducted system, provided it is only cooling or heating the rooms in use. However, once a family is regularly running multiple splits for long periods, a well-designed zoned ducted system can be equal to or even cheaper to run per room.
Ultimately, running costs depend less on the label “ducted” or “split” and more on how many rooms are conditioned, how efficiently the system is designed and how smartly it is used in the climate.
Split systems are typically the lowest cost option for running one main living area or a bedroom. The indoor unit cools a single room, so there are no duct losses in the roof space and no energy spent on areas that are not used.
For example, a modern 2.5 kW split in a bedroom might use around 0.5 to 0.7 kWh per hour on a typical summer evening. With Queensland residential tariffs, this is usually only a small cost per night if the temperature is set around 24 to 25°C and the unit is correctly sized.
Key situations where splits are usually cheaper to run include:
In these cases, a ducted system would be running a much larger fan and outdoor unit than necessary, increasing hourly running costs for the same conditioned space.
A high-efficiency ducted system with proper zoning can be very competitive once a household regularly cools or heats most of the home. If three or more split systems are running at the same time, the combined power draw often approaches that of a single ducted system that serves the same areas.
Modern ducted systems with variable speed (inverter) compressors and supply air temperature control can ramp output up and down very efficiently. If the ductwork is well insulated and designed with minimal leakage, more of the cooled air reaches the rooms and less energy is wasted in the roof space, which narrows the gap with splits.
For a typical four-bedroom home where several rooms are used at once, a zoned ducted system can reduce running costs by letting the household turn off unused zones such as guest rooms while still conditioning the living space and main bedrooms.
Picking between ducted and split system air conditioning is not about which system is “better” in isolation, but which is better matched to your property, your lifestyle and your long‑term budget. Ducted systems suit larger homes and households wanting whole‑of‑home comfort. Split systems, on the other hand, can be more cost‑effective upfront and to run in smaller homes and apartments. The way you use your air conditioning has as much impact on your power bill as the technology you choose. The most economical result comes from a correctly designed, properly installed system that’s tailored to your home’s layout and your family’s patterns of use. Rather than just the purchase price, you can make a decision that delivers both comfort and value for many summers to come.
