Brands and System Costs
The brand and capacity of your ducted system is one of the biggest cost variables. All major brands now use R32 refrigerant and inverter compressors as standard.
Supply and installation combined typically adds $4,000–$8,000 on top of the unit price, depending on ductwork complexity. A Daikin 10kW system supplied and installed starts from around $5,800. A 14kW system from around $6,700 (supply and basic install, excluding ductwork). Full turnkey installations with new ductwork, zoning, and electrical run $9,000–$18,000+ depending on home size.
ActronAir is the only major brand designed and assembled in Australia, which some homeowners prefer for local service support and parts availability. The Japanese brands (Daikin, Mitsubishi Electric, Fujitsu) dominate the premium end and generally have the widest installer networks.
Zoning and Smart Control Systems
Zoning is one of the most cost-effective upgrades for a ducted system. Rather than heating or cooling the entire house at once, zone control uses motorised dampers in the ductwork to direct airflow only to occupied rooms.
A 4-zone smart controller adds 20–30% to the total installation cost but typically pays for itself within 3–5 years through lower energy bills. For homes with 4+ bedrooms, zoning is where the long-term savings are.
Ductwork Types and Costs
The ductwork is the hidden cost in any ducted installation. New ductwork for a 3–4 bedroom home typically adds $2,500–$5,000 to the project.
Insulated flexible duct (most common residential): R1.0 insulation is the NCC minimum, but R1.5–R2.0 is recommended for residential applications, particularly in hot roof spaces. Polyaire and Supa Flex are common Australian suppliers. Material cost runs $15–$30 per metre depending on diameter and R-value.
Rigid galvanised steel duct: More durable and better airflow performance, but harder to install and primarily used for main trunk lines and plenums. Material cost runs $40–$80 per metre installed.
Plenum box: The distribution hub that connects the indoor unit to the duct runs. A standard plenum costs $200–$500.
Under AS 4254.1, all ductwork must include vapour barriers to prevent condensation. In hot roof spaces (common in Brisbane and Perth where cavity temperatures exceed 60°C), R2.0 insulation is strongly recommended. Without adequate insulation, cooled air picks up heat before it reaches the room, wasting energy and reducing comfort.
System Sizing: Getting It Right
Correct sizing is the single most important factor in a ducted installation. An undersized system runs constantly and never reaches the set temperature. An oversized system short-cycles, wastes energy, and fails to dehumidify properly.
General capacity guidelines for standard 2.4m ceiling heights:
Small home (2–3 bedrooms, ~100 m2): 7–10 kW
Medium home (3–4 bedrooms, ~150 m2): 10–14 kW
Large home (4–5 bedrooms, ~200 m2): 14–18 kW
Very large home (5+ bedrooms or two-storey, 250+ m2): 18–24 kW
Adjust upward for poor insulation, large west-facing windows, high ceilings, or extreme climate zones (Perth, western Sydney). A good installer will conduct a heat load calculation that factors in orientation, insulation, window area, and local climate zone rather than relying on floor area alone.
Systems above 12kW typically require three-phase power. If your home is on single-phase, a three-phase upgrade adds $3,000–$5,000 or more, depending on distance from the street transformer.
Signs You Need Ducted Air Conditioning
Cooling or heating more than three rooms with separate split systems (running costs exceed a single ducted system)
Existing ducted system is 15–20 years old with declining performance, higher energy bills, or frequent repairs. Before committing to replacement, compare a quote for
air conditioning repair or service, typically $150–$1,600 per job, with the cost of a new system.
Building a new home or doing a major renovation (installation is far cheaper during construction)
Open-plan living areas where split systems cannot distribute air evenly
Gas ducted heating reaching end of life (reverse-cycle electric is more efficient and handles both heating and cooling)
Existing ductwork showing visible condensation, sagging, or disconnected joints
What Affects the Cost
House size and number of zones. A 3-bedroom home with a single zone is a fundamentally different job to a 5-bedroom home with 4 zones. More rooms means more ductwork, more diffusers, and a larger capacity unit.
Roof space access. The indoor unit needs at least 500mm clearance in the roof cavity. Low-pitch roofs, cathedral ceilings, or cluttered roof spaces add significant labour time or may require slim-line indoor units designed for tight spaces.
New installation vs replacement. Replacing an existing ducted system reuses existing ductwork routes and penetrations, saving 30–40% compared to a full new install. However, old ductwork (15+ years) often needs replacing due to degraded insulation and loose joints.
Zoning configuration. A basic single-zone system cools the entire house at once. Smart zone controllers (AirTouch, iZone) with individual room temperature sensors add $2,500–$4,500 but reduce running costs by only conditioning occupied rooms.
Single-phase vs three-phase power. Systems above 12kW typically need three-phase power. If your home is on single-phase, the three-phase upgrade is a separate and significant additional cost. Your switchboard must also have capacity for the dedicated circuit; if a
full board replacement is needed, budget $1,000–$3,600 per job separately from the three-phase supply upgrade.
Insulation quality. A well-insulated home needs a smaller capacity system. Poor insulation means oversizing the unit, which costs more upfront and more to run.
Brand and efficiency rating. Premium brands (Daikin, Mitsubishi Electric) with higher energy star ratings cost more upfront but deliver lower running costs and longer service life.
Existing ductwork condition. If existing ductwork has degraded R-value, condensation damage, or loose joints, it needs replacing alongside the new unit. Flex duct in hot roof spaces may only last 10–12 years before insulation deteriorates.
A straightforward replacement in a single-storey, 3-bedroom home with good roof access, existing ductwork in serviceable condition, and single-zone control sits toward $8,200. A new installation in a 5-bedroom, two-storey home with limited roof access, 4-zone smart control, three-phase power upgrade, and premium brand unit pushes toward $22,400.
Government Rebates and Incentives
Ducted air conditioning rebates are strongest in Victoria, where replacing gas ducted heating with efficient reverse-cycle systems is a government priority.
Victoria: Victorian Energy Upgrades (VEU). The VEU program provides upfront discounts through accredited providers when replacing gas ducted heating with reverse-cycle electric. Discounts of up to ~$5,530 are available for a ducted reverse-cycle replacement, or up to ~$7,200 for a multi-head split system replacing gas ducted, with a $1,000 minimum co-payment. From 31 March 2025, all VEU-installed products must include a 5-year warranty. The discount is applied at point of sale by accredited VEU providers who generate Victorian Energy Efficiency Certificates (VEECs) and pass the value to you as a reduced price. The program has been extended to 2045.
South Australia: Retailer Energy Productivity Scheme (REPS). Energy retailers in SA provide discounts on efficient reverse-cycle air conditioning as part of government-mandated energy productivity targets. The discount varies by retailer and system type. REPS Phase 2 runs 2026 to 2030. Note: REPS activities are generally permitted only once per address.
Federal: Household Energy Upgrades Fund (HEUF). The CEFC-backed fund offers discounted finance (low-interest loans) through participating lenders for energy-efficient upgrades including ducted air conditioning. This is not a direct rebate but can reduce the financing cost of a large installation.
NSW, QLD, WA: No state-specific ducted air conditioning rebate programs. The federal HEUF discounted finance is the main option.
City and Regional Price Comparison
Prices vary across Australia due to differences in labour rates, climate demands, housing construction, and trade pool size.
At the city level, Sydney is the baseline at $8,200–$22,400 per system. Melbourne tracks close to Sydney pricing, with the added factor that reverse-cycle ducted systems are standard (used for both heating and cooling year-round). Victoria also offers significant discounts through the Victorian Energy Upgrades (VEU) program for homeowners replacing gas ducted heating with reverse-cycle electric: up to ~$5,530 for a ducted reverse-cycle replacement, or up to ~$7,200 for a multi-head split system replacing gas ducted, with a $1,000 minimum co-payment. From 31 March 2025, all VEU-installed products must include a 5-year warranty. Brisbane's subtropical climate means heavy cooling loads and larger capacity systems, but timber-framed construction makes installation easier. Perth and Adelaide quotes reflect smaller installer pools and demand during extreme summer heat; see the Pricing by City table for local ranges.
Within any city, the range shifts based on home size, roof construction, and system complexity. Newer estates in outer suburbs with open roof cavities, modern insulation, and pre-wired electrical tend to sit at the lower end. Established inner-city homes with low-pitch roofs, limited cavity space, or heritage restrictions push costs higher. Two-storey homes add complexity regardless of suburb: running ductwork between levels requires floor penetrations and more creative duct routing, significantly increasing labour time compared to a single-storey roof space install.
How We Calculate
Estimates are based on surveyed trade rates for licensed air conditioning technicians holding ARC (Australian Refrigeration Council) authorisation, adjusted for each state and property type. All prices include GST. Figures reflect standard residential ducted air conditioning systems. For smaller homes or single-room cooling, a split system is an alternative costing $1,500–$10,200 per system supplied and installed, with single-room units toward the lower end. Commercial installations and specialised applications are not included.