A commercial kitchen exhaust system in NSW needs to be treated as a complete air-handling and safety system, not simply a stainless-steel hood with a fan. The applicable NCC/BCA provisions, referenced Australian Standards, NSW variations and approved project documents determine the compliance pathway.
General information only: This guide is not project-specific certification or engineering advice. Confirm the applicable NCC edition, referenced Standards, NSW requirements, approval pathway and approved design documentation for each project.
What “compliant” actually means
For a commercial kitchen, compliance is not established by one component label or a single airflow number. It is an outcome supported by the correct design basis, suitable equipment, coordinated installation, required approvals and verifiable commissioning records.
A useful way to understand the framework is in four layers:
- The National Construction Code (NCC), including the Building Code of Australia provisions and the edition adopted for the project.
- The Australian Standards referenced by that NCC edition or the approved design, including the applicable editions of AS/NZS 1668.1 and AS 1668.2.
- NSW variations, legislation, approval conditions and requirements of the relevant consent authority or certifier.
- The project-specific design, equipment selections, installation details, inspection results and commissioning evidence.
These layers need to be read together. Standards Australia released AS 1668.2:2024 as the latest published edition, while an applicable NCC edition may call up a particular referenced edition. During a code transition, the newest published Standard is not automatically the edition that governs every project. The project approval date, adopted code, transition arrangements and approved documentation must be checked.
When is a commercial kitchen exhaust hood required?
NCC 2022 Volume One provision F6D12 requires a commercial kitchen exhaust hood complying with AS 1668.1 and AS 1668.2 where either of the following triggers is met:
- Any individual cooking apparatus has a total maximum electrical power input greater than 8 kW or a total gas power input greater than 29 MJ/hour.
- The combined maximum input of more than one appliance exceeds 0.5 kW of electrical input per square metre of room or enclosure floor area, or 1.8 MJ/hour of gas input per square metre.
Those thresholds are a starting point, not a complete design. The applicable NCC edition and its state variations must be confirmed, and other requirements or approval conditions may still affect the exhaust, ventilation, fire-safety, food-premises or environmental outcome. Appliance changes can also alter the design basis even when an existing hood remains in place.
The parts of a complete kitchen exhaust system
Exhaust hood and capture zone
The hood must be selected and positioned for the actual cooking process. Appliance duty, heat, steam, smoke, grease production, hood type, mounting height, overhang and nearby air movement all influence whether the plume is captured before it spills into the kitchen.
Grease filtration
Filters are part of the contamination-control strategy. Their type, arrangement, face velocity, condition and accessibility affect grease removal, pressure loss and cleaning. A filter that looks clean does not prove that downstream ductwork or the fan is clean or performing correctly.
Ductwork and access
The duct route must be coordinated with structure, fire-rated construction, services, cleaning access and discharge location. Poor transitions, tight bends, undersized sections, internal obstructions and inaccessible grease-laden runs can increase resistance, reduce airflow and make maintenance more difficult and expensive.
Exhaust fan and discharge
The fan must deliver the design airflow against the total system resistance, not merely match a nominal free-air rating. Selection should consider the duty point, grease exposure, temperature, access, weather, noise, vibration, controls and safe maintenance. The discharge arrangement also needs to limit recirculation, nuisance and interaction with air intakes, boundaries and nearby occupancies in accordance with the applicable requirements.
Replacement or make-up air
Air removed from the kitchen has to be replaced. If replacement air is inadequate or poorly distributed, the space can become strongly negative. Doors may become difficult to open, conditioned air can be pulled from adjoining areas, draughts can cross the hood face and smoke or heat can escape from the capture zone. More fan speed is not always the solution; the supply and exhaust air paths need to be considered together.
Controls and interlocks
Controls should support safe and practical operation. Depending on the design, this may include coordination between exhaust and replacement-air systems, appliance operation, variable-speed controls, monitoring, fire-system interfaces and accessible isolation. The required arrangement must be established by the applicable design and Standards rather than assumed from a previous tenancy. Learn more about kitchen exhaust VFDs, controls and interlocks.
The design inputs that matter most
A cost-effective design starts with accurate inputs. Oversizing can increase fan energy, noise, replacement-air loads and equipment cost. Undersizing can lead to smoke spillage, excessive heat, poor working conditions, odour complaints and repeated repair attempts.
- A complete appliance schedule with equipment type, dimensions, fuel, maximum input and proposed position.
- The cooking duty and likely production profile, including peak periods and future menu changes.
- The room layout, hood mounting constraints, ceiling height, cross-draught sources and adjacent spaces.
- The proposed duct route, available risers, roof or wall discharge constraints and access for cleaning.
- The replacement-air source, quantity, temperature treatment and delivery pattern.
- Fan duty, system resistance, electrical supply, speed control, noise and vibration constraints.
- Fire separation, smoke control, service penetrations and other coordination requirements.
- The approval pathway, project stage, adopted NCC edition and referenced Standards.
Why airflow alone does not prove performance
An airflow measurement is valuable, but it needs context. The correct question is whether the measured system performs against the approved design and captures the cooking plume under representative operating conditions.
A commissioning check may need to consider:
- Exhaust and replacement-air quantities at defined measurement locations.
- Fan speed, motor condition, rotation, belt condition and control operation.
- Filter installation and cleanliness at the time of testing.
- System static pressure or other diagnostic readings where relevant.
- Hood capture and containment during representative appliance operation.
- Room pressure effects, door operation and air transfer from adjacent spaces.
- Noise, vibration, discharge behaviour and visible leakage.
- Access, labelling, as-built information and maintenance handover.
The required test method and acceptance criteria should come from the approved design and applicable Standards. A single reading taken at an easy access point should not be presented as proof of whole-system compliance without that context. See Altruism NSW’s commercial kitchen airflow testing and ventilation reports.
Common problems in existing NSW kitchens
The appliance load changed but the exhaust system did not
A tenancy fit-out, menu change or higher-duty appliance can increase heat and contaminant loads. Reusing the existing hood, fan and ductwork without checking the revised appliance schedule can leave the system underperforming or inconsistent with the new approval basis.
The fan was replaced by size rather than duty
Two fans with similar casing or motor ratings may deliver different airflow against the installed resistance. A replacement should be selected from the required duty point and verified after installation. Review the available fan and motor replacement options.
Filters and ductwork are restricting the system
Grease loading, damaged filters, internal obstructions or poorly executed duct changes can reduce airflow and increase fire and maintenance risk. Cleaning the visible hood alone does not address the complete air path. Altruism NSW does not provide grease cleaning; this work should be completed by a specialist commercial exhaust cleaning contractor.
Replacement air is missing or creating cross-draughts
A strong exhaust fan can depressurise the kitchen, while a poorly positioned supply diffuser can push the cooking plume out of the hood. Air quantity and distribution both matter.
No reliable commissioning or as-built record exists
Without drawings, appliance data, design airflow, fan selection and test results, fault diagnosis becomes slower and upgrade decisions become less certain. Establishing a measured baseline is often the most economical first step.
A practical project checklist
- Confirm the project location, building classification, approval pathway and applicable NCC edition.
- Freeze the appliance schedule before final hood and airflow design.
- Confirm the referenced editions of AS/NZS 1668.1 and AS 1668.2 for the project.
- Coordinate hood, filters, duct route, fan, discharge, replacement air, controls and fire-related interfaces.
- Provide safe cleaning, inspection and maintenance access.
- Record approved drawings, equipment selections and control requirements.
- Commission under representative conditions and retain test results and as-built information.
- Reassess the system when appliances, menu, tenancy layout, ductwork, fan or controls change.
Frequently asked questions
Does every commercial kitchen need an exhaust hood?
Not solely because the premises is called a commercial kitchen. NCC F6D12 uses appliance-input and room-area thresholds, but the applicable NCC edition, project conditions and other approval requirements must be checked. Many normal restaurant cooking arrangements meet the trigger.
Which edition of AS 1668.2 applies?
AS 1668.2:2024 is the latest published edition. The edition required for a particular project depends on the NCC edition adopted in the jurisdiction, any transition provisions, the approval date and the approved design documents. Confirm the project basis before designing, quoting or stating compliance.
Can a larger exhaust fan fix smoke spilling from the hood?
Sometimes insufficient exhaust is part of the problem, but fan speed alone can worsen negative pressure, noise and energy use. Hood geometry, filters, duct resistance, fan duty, cross-draughts and replacement-air distribution should be diagnosed together.
Can the existing exhaust system be reused for a new restaurant?
Potentially, but reuse should follow an assessment of the new appliance schedule, hood capture, duct condition and access, fan duty, discharge, replacement air, controls, fire coordination and approval requirements. Existing equipment should not be assumed suitable because it operated for the previous tenant.
What should we provide for an initial assessment?
Start with the appliance schedule, kitchen layout, available mechanical drawings, fan details, photographs of the hood, filters, duct route and discharge, known complaints, maintenance history and any previous test records. This makes the first review faster and more cost-effective.
Plan the system before buying components
The lowest-cost compliant solution is usually the one that resolves the full air path early, coordinates the building constraints and leaves practical access for commissioning and maintenance. Buying a hood or fan before confirming the appliance load, duct route and replacement-air strategy can create expensive rework.
Official references
- NCC 2022 Part F6 — Light and ventilation — see F6D12 for kitchen local exhaust ventilation.
- NCC 2022 NSW Part F6 variation — NSW-specific ventilation provision.
- ABCB general NCC guidance — NCC status and jurisdictional adoption guidance.
- Standards Australia: AS 1668.2:2024 overview — publisher summary of the latest mechanical ventilation edition.
- Standards New Zealand: AS/NZS 1668.1:2015 — official catalogue description for fire and smoke control.
This article provides general information only and is not engineering, certification, legal or insurance advice. Requirements must be confirmed for the specific building, approval, system and scope.