The best air conditioning choice usually becomes clear when you map how your household uses the house. Ducted air conditioning can deliver a discreet, coordinated system across several rooms. Separate split systems can give individual rooms straightforward control and let you stage the installation. Neither arrangement automatically wins on comfort, appearance or running cost.
For more detail on this part of the project, see Retrofitting Zones to Existing Ducted Air Conditioning: What to Check.
For an Australian renovation, the decisive issues are the finished layout, access for services, the rooms occupied together and the quality of the installation. A beautifully concealed system can disappoint if bedrooms have poor airflow. An efficient wall unit can also disappoint if it blows directly across the dining table or cannot reach the space around a new corner.
Start with the house you are creating, rather than the equipment already advertised. A renovation that improves insulation, shading and draught control may need a different system from the same house before work. Include heating and cooling in your sustainable renovation plan before selecting equipment.
Understand what you are actually comparing
Ducted reverse-cycle air conditioning
A ducted system usually has a central indoor unit connected to outlets through a network of ducts, together with outdoor equipment. The indoor unit and ducts may occupy roof space, a bulkhead or another designed service zone. A return grille draws room air back to the indoor unit.
The visible room components can be relatively discreet, but that does not make the installation small. Duct routes, return paths, access panels, insulation and drainage all need space. Existing shallow roof cavities and complicated extensions can make this harder than a floor plan suggests.
Individual split systems and multi-splits
A single split system connects one indoor unit with one outdoor unit. Several individual systems provide independent appliances for different areas. A multi-split connects multiple indoor units to shared outdoor equipment; it is a separate configuration worth pricing rather than treating as identical to several single splits.
Wall-mounted heads are familiar, but indoor formats also include floor consoles and selected concealed or cassette arrangements. Available configurations depend on the manufacturer. Ask the installer to identify the exact indoor and outdoor model pairing instead of quoting only a brand and nominal capacity.
Shared equipment changes the comparison
With a multi-split, shared outdoor capacity and the combination of rooms operating at once matter. Ask what each room can receive during simultaneous demand and what happens when only one small bedroom needs conditioning. This is more useful than assuming every indoor unit can always deliver its headline capacity independently.
Choose around occupancy, not the number of bedrooms
Imagine a household where one person works at home while everyone else is away. Conditioning a study through a separate split may be practical. Now imagine a household using bedrooms, a living area and a home office at the same time. A well-designed ducted installation may offer convenient whole-home coverage.
Write down the actual routine for weekdays, weekends and nights. Include bedrooms used by children, shift workers or older family members, and rooms that are often empty. Guest rooms should not carry the same design priority as regularly occupied rooms unless you deliberately want that flexibility.
- Which rooms need heating or cooling together?
- Which rooms need different schedules?
- Do people keep bedroom doors closed overnight?
- Will a future extension change the occupied floor area?
- Is heating, cooling or both the main comfort problem?
This exercise often reveals that a mixed approach deserves a quote: for example, retaining a suitable existing living-room split and adding bedroom systems during later work. Coordinate that option with a staged renovation so access is not closed before future services are considered.
Check whether the renovated building can accommodate ducting
A ducted quotation needs more than a room count. The contractor should inspect the proposed indoor-unit location and practical routes to each outlet. A plan that requires repeated tight bends, squeezed ducts or inaccessible joints deserves another look before you agree to bulkheads or ceiling changes.
Two-storey homes need particular coordination. Getting air from one roof space to a downstairs room may require a vertical service route through joinery or a cupboard. A new extension can also interrupt the route between existing and proposed ceilings. Show the heating contractor structural drawings, ceiling sections and joinery plans early.
Service access is part of the finished design. The indoor unit, filters, drains, zoning components and other serviceable equipment must remain accessible. Ask where a technician will stand, what must be removed and whether a future replacement can pass through the available opening. A hidden unit is only convenient while it can be maintained.
Existing ducts are not automatically suitable for new reverse-cycle equipment. Their condition, sizing, insulation and layout require assessment. If reuse is proposed, have the quotation state exactly what stays and what testing supports that decision. The guide to air conditioning duct replacement explains why replacing the main appliance alone may leave an old distribution problem unresolved.
Compare comfort room by room
Ducted systems can provide an even visual result, but room comfort depends on outlet placement, airflow, zoning and return-air design. A sunny living room and a shaded bedroom have different loads. The same outlet size in both rooms is not evidence that the design responds to those differences.
Split-system placement requires equally careful thought. Discuss airflow across sofas, beds and workstations, access to filters, the appearance of pipe covers and the path of condensate drainage. A head placed wherever installation is cheapest may create an unpleasant draught across the main seating position.
Closed bedroom doors matter
For ducted systems, ask the designer how supplied air returns when doors are closed. Do not assume air will find a suitable route. Door details, transfer arrangements or other design measures need to work with privacy and acoustic expectations. This becomes especially important when a renovation adds improved door seals.
For individual splits, a closed bedroom can be treated independently, but the system still needs appropriate capacity and controls. Ask about low-load operation at night rather than focusing only on performance during the hottest afternoon. A large unit is not automatically the most comfortable bedroom choice.
Use the right capacity information
Cooling capacity and electrical consumption are different measurements. A capacity figure describes the heating or cooling delivered, not simply the electricity drawn from the meter. For meaningful comparisons, request the exact equipment schedule and an explanation of how the contractor sized it for the finished building.
The Australian Government’s Your Home guidance recommends choosing systems that suit the climate, building and pattern of use. It also distinguishes individual room conditioning from central systems. For relevant non-ducted products, the Zoned Energy Rating Label provides climate-based heating and cooling information; some ducted products provide that label voluntarily.
Compare ratings within appropriate equipment types and capacities, then discuss how the proposed installation affects real operation. The equipment rating does not measure the workmanship of the ducts, the quality of zoning or whether the outdoor unit has suitable airflow. Our guide to sizing air conditioning after a layout change covers the information a contractor needs.
Be precise about zoning and controls
“Zoned ducted air conditioning” can describe very different arrangements. One system may divide the house into broad living and sleeping areas. Another may offer more individual room control. Ask which rooms have their own temperature sensing, which outlets open together and what minimum operating area the design requires.
A zone button is not necessarily an independent thermostat. If the main sensor sits in a hallway, a bedroom may feel different from the displayed temperature. Have the installer explain the control sequence using an ordinary situation: one bedroom occupied overnight, all other rooms unused, and the bedroom door closed.
With individual splits, remote controls provide simple local operation, but managing several appliances may become tiresome for some households. Decide whether central scheduling is valuable and whether basic operation remains available without internet access. Choose controls family members can understand without repeatedly opening an app.
Allow for noise inside and outside
Indoor noise can come from airflow, the fan, vibration or unsuitable grille selection. Ask for relevant manufacturer sound information and discuss the fan speed likely to be needed in normal use. A quietest-mode figure is less helpful if the room requires a higher setting most evenings.
Outdoor locations deserve careful consideration near bedrooms, neighbouring properties and narrow side passages. A tucked-away unit might be visually appealing while creating difficult airflow or noise conditions. Local rules and property constraints vary, so the installer should assess the actual location rather than relying on a generic setback assumption.
In apartments and townhouses, obtain the necessary body corporate or owners corporation consent before committing to penetrations, external equipment or common-property work. Read apartment renovation rules alongside the property’s own requirements. Approval for one neighbour’s system does not automatically authorise yours.
Compare complete installation costs in AUD
There is no useful national price comparison without a defined scope. Ducted installations can include equipment, ducts, zoning, grilles, electrical work, drainage and ceiling repairs. Multiple splits involve repeated mounting, pipe routes, drains and electrical connections. Difficult access can change either total substantially.
The following is an illustrative budgeting exercise, not a current market quotation. Suppose a household receives a complete ducted proposal for AUD $16,000 including GST, plus AUD $1,500 for separately quoted ceiling and painting work. Its comparable project allowance is AUD $17,500. If three independently quoted splits total AUD $10,500 including GST, plus AUD $1,000 for repairs and concealed routing, their comparable allowance is AUD $11,500.
Those invented figures show how to compare scope, not what your installation should cost. The AUD $6,000 difference might buy whole-house coverage that the split proposal does not provide. Alternatively, it might pay for rooms the household rarely uses. Count the conditioned rooms and performance assumptions before deciding the difference represents value.
- List every indoor and outdoor model.
- Identify room coverage and simultaneous-use assumptions.
- Separate electrical upgrades from appliance connection.
- Include removal, disposal and making good.
- State whether GST, controls and commissioning are included.
- Clarify access equipment and any approval costs.
Use the same written brief when comparing renovation quotations. A cheaper quote with fewer rooms, less electrical work or exposed pipework is a different offer.
Estimate running costs from likely use
A meaningful running-cost estimate starts with operating hours, tariff assumptions and the power used under those conditions. Nameplate capacity alone cannot produce a reliable bill forecast. Weather, thermostat settings, building performance and the number of active zones all matter.
For an explicitly illustrative calculation, a system averaging 1.2 kW of electrical input over five hours uses 6 kWh. At an assumed electricity rate of AUD $0.35 per kWh including GST, that session costs AUD $2.10. This excludes any tariff complications and says nothing about which system will average that input in your house.
Ask a contractor making a savings claim to show their assumptions. Savings should not rely on comparing a small room conditioned by splits with an entire house conditioned by ducts. Match the comfort service first. Solar generation may offset some daytime consumption, but the result depends on timing and household electricity use.
Set the installation and handover expectations
Arrange equipment selection before walls and ceilings close. Coordinate outdoor locations with paths, landscaping, future decks and other services. Ensure the electrical contractor assesses supply and protection requirements, while appropriately licensed refrigeration professionals handle regulated refrigerant work. Homeowners should not attempt electrical connections or refrigerant disconnection.
At handover, operate the system in the situations that shaped the design. Check living zones, individual bedrooms and night settings. Ask the installer to explain filters, drainage, maintenance access and the procedure for reporting an uneven room. Keep commissioning information, model details and warranties with the renovation documents.
The strongest choice is the one that matches your daily use and fits the actual building. Choose ducted air conditioning when coordinated coverage, concealed outlets and a feasible duct design justify the investment. Choose individual splits when independent rooms, staged expenditure and simpler service routes better match your household. Let a complete design and comparable quotation settle the decision.