Commercial Kitchen Ventilation Requirements Australia | Guide

Commercial Kitchen Ventilation Requirements in Australia: AS 1668, Hoods, Makeup Air & Fire Suppression

Getting your commercial kitchen ventilation requirements right in Australia is not optional — it is the single biggest compliance risk between you and a council shutdown notice, a failed insurance claim or, worst case, a fire that takes out the venue. Every commercial kitchen in the country, from a café fitout in Surry Hills to a 200-cover restaurant in Fortitude Valley, is governed by AS 1668.1, AS 1668.2 and Section F of the NCC — the documents that dictate how much air your hood must extract, how it must be replaced, and how the exhaust system must be built so it does not become a grease-fed chimney.

This guide walks operators through the rules in plain English: AS 1668 essentials, hood sizing, make-up air, AS 1851 fire suppression integration and state quirks. It is the compliance-focused companion to our broader commercial kitchen ventilation guide and our kitchen health inspection checklist.

What AS 1668 Says — Air Change Rates and Exhaust Calculations

AS 1668.1 covers fire and smoke control aspects of mechanical ventilation in buildings, while AS 1668.2 sets the mechanical ventilation requirements for acceptable indoor air quality. Together they form the backbone of every commercial kitchen ventilation system in Australia, and certifying engineers cite them line-by-line when signing off your fitout. Full text is available on the Standards Australia website to compliant operators and certifiers.

For a Type 1 kitchen (any space with cooking equipment that produces grease-laden vapour — fryers, chargrills, woks, salamanders, combi ovens on high-heat modes), AS 1668.2 sets out minimum exhaust rates expressed in litres per second per linear metre of hood length, or per kilowatt of cooking appliance input. Typical Australian design figures end up in the range of 0.4–1.0 m³/s per metre of hood depending on the appliance class — light-duty (steamers, kettles) at the low end, heavy-duty (open-flame chargrills, woks) at the top.

Minimum air change rates for the kitchen space itself usually sit at 20–40 air changes per hour (ACH), with higher rates demanded over hot, grease-heavy cooking lines. A 60 m² kitchen at a 3 m ceiling height (180 m³ volume) at 30 ACH needs the system to move 5,400 m³ of air every hour — about 1,500 L/s. Undershoot that and you get visible smoke creep, grease deposits on light fittings, and almost certainly a non-conformance at your next council health inspection.

The other AS 1668 number that catches operators out: capture velocity. The face velocity at the hood lip needs to sit at roughly 0.4–0.5 m/s to actually pull greasy vapour up rather than letting it spill into the kitchen. Hoods sized only on extraction volume — without checking face velocity — frequently fail in practice, even when the fan numbers look correct on paper.

Commercial Kitchen Exhaust Hood Requirements: Five Hood Types Explained

Choosing the right hood is the most expensive decision in your ventilation system — get it wrong and you are paying twice. Here are the five hood configurations used in Australian commercial kitchens, with realistic costs, pros and cons.

1. Wall-mounted canopy hood

Sits against a back wall, hanging over a single cooking line. The default choice for 80 % of café and small restaurant kitchens. Material: 1.2 mm 304 stainless steel minimum, with integral grease baffle filters rather than mesh filters (mesh is non-compliant for heavy-duty service under AS 1668.2). Cost: $2,500–$8,000 installed for a standard 1.8–3.0 m hood.

2. Island canopy hood

Suspended over a central cooking island, open on all four sides. Needs 20–30 % more exhaust than a wall hood of the same length because there is no back wall containing the plume. Cost: $6,000–$15,000 installed. Common in open-plan restaurants and demonstration kitchens.

3. Proximity (low-profile) hood

Hangs only 300–500 mm above the appliance instead of the standard 600–900 mm. Captures vapour at a tighter zone so it can run at a lower extract rate — useful where ceiling height is tight (food courts, container kitchens, basements). Cost: $4,000–$10,000 installed.

4. Ventless (recirculating) hood

Uses HEPA + carbon filters and ESP (electrostatic precipitator) modules to clean the air rather than ducting it outside. Genuinely useful where no roof penetration is possible — historic buildings, ground-floor tenancies in residential strata, pop-up kitchens. Cannot be used with open-flame or solid-fuel cooking under AS 1668.2 and the NCC. Cost: $8,000–$25,000+ for the unit alone.

5. Condensate (steam) hood

Designed for steam-only loads — combi ovens in steam mode, kettles, pasta cookers. Captures water vapour without the heavy grease-filter system, but is not rated for grease-laden cooking. Cost: $2,000–$6,000 installed.

Calculating Ventilation Requirements: A Worked Australian Example

Here is the actual sum a mechanical engineer would run for a 25-seat suburban café in Melbourne with a single chargrill, two-burner stove and benchtop fryer along a 2.4 m wall hood:

The numbers look fine for the hood itself, but watch the makeup air row — at 1,836 L/s you have to architect a way to bring almost the entire exhaust volume back in tempered (heated in winter, cooled in summer) from outside, or you starve the hood and the kitchen goes negative-pressure.

Commercial Kitchen Make-up Air: The 80–90 % Rule

Make-up air (also written "makeup air") is the conditioned outdoor air your system supplies back into the kitchen to replace what the hood is extracting. Australian best practice and the standards both require make-up air to be sized at 80–90 % of exhaust airflow, and that fresh air supply is what protects indoor air quality for staff working long shifts at the cookline.

Skip it or undersize it and you create negative pressure, which causes:

• Back-drafting at the hood — vapour spills out rather than being captured, even at the right extract rate
• Doors that "suck open" from neighbouring tenancies, dragging dust and odour into your kitchen
• Gas appliances flaming yellow or pilot lights going out — a genuine carbon-monoxide and fire risk
• Burnt-out exhaust fans running against excessive static pressure, halving expected lifespan

Three makeup air systems used in Australia:

1. Dedicated outdoor air unit (DOAS) — separate roof-mounted unit, tempered. Best practice for any kitchen over 1,000 L/s of exhaust. $15,000–$40,000+ installed.
2. Hood-integrated supply (short-circuit hood) — supply air injected within the hood itself. Cheaper but less effective for capture; not always permitted.
3. Transfer air — drawing makeup air from the (conditioned) dining room. Only acceptable for small kitchens and can wreck dining-room comfort if oversized.

Fire Suppression Integration — AS 1851 and Wet Chemical Systems

Every commercial kitchen exhaust hood in Australia working with grease-laden cooking is required to have an automatic wet chemical fire suppression system integrated into the hood and the duct run. The two standards that matter here:

• AS 4587 (and US UL 300) — the manufacturing standard for the suppression equipment itself (Ansul R-102, Amerex KP, Buckeye Kitchen Mister are common compliant brands installed in Australia)
• AS 1851 — the routine service standard. Suppression systems require 6-monthly inspections plus a full 12-monthly test by a licensed fire technician

When the suppression system trips, it must simultaneously:

• Discharge wet chemical agent onto every cooking appliance in the protection zone
• Shut down gas to the cookline via a mechanical fusible link or solenoid
• Shut down electricity to the cookline
• Continue exhaust fan operation for at least 15 minutes after discharge to clear smoke and unspent chemical

For the full inspection-readiness picture including suppression, sprinkler and extinguisher servicing, see our commercial kitchen fire safety guide. Skipping or expiring an AS 1851 service is one of the single most common findings on insurance claim denials in Australian hospitality.

Ductwork Requirements: Material, Slope and Access

Grease ductwork from the hood to the discharge point is the most highly regulated component of the entire system. Under AS 1668.1 and AS/NZS 1530.3, the ductwork must be:

• Minimum 1.2 mm 304 stainless steel for grease ducts (mild steel is non-compliant for new installs)
• Continuously welded at every seam — riveted or screwed seams leak grease vapour and pose a fire risk
• Sloped back toward the hood at minimum 1:60 (about 17 mm per metre) so condensed grease drains back to the collection point rather than pooling in low spots
• Fitted with access panels at every change of direction and at intervals no greater than 3 metres along straight runs, to allow physical cleaning
• Sleeved through fire-rated walls and floors with a fire damper or equivalent rated penetration system

Discharge must be either at roof level, vertically upward, at least 1 m above the highest roof point within a 10 m radius, or to a side wall location that complies with the separation distances in AS 1668.2 from openable windows and air intakes. Discharging sideways under an awning, into a courtyard, or next to a neighbour's bedroom window is non-compliant — and the source of roughly half the noise and odour complaints local councils receive on hospitality precincts.

For the cleaning and inspection cycle that keeps this ductwork compliant, see our commercial kitchen equipment maintenance schedule.

State-by-State Variations in Australia

While AS 1668 and the NCC apply nationally, each state layers its own occupational, fire-services and council planning rules on top:

Always check with your local council before signing off the mechanical drawings — a designer working interstate often misses a local development application condition.

Energy Efficiency and Cost Savings for Australian Operators

Compliance is not the only reason to get your mechanical ventilation right — HVAC and exhaust together account for 25–35 % of total kitchen energy use, second only to refrigeration. A tuned-up exhaust system delivers real cost savings:

• Variable-speed exhaust fans with hood sensors throttle airflow when the cookline is idle, cutting exhaust energy use by 30–50 %
• Demand-control kitchen ventilation (DCKV) pays back in 18–36 months on most mid-size restaurants
• Heat recovery on make-up air units recaptures conditioning energy — valuable in Melbourne and Hobart winters
• Regular maintenance of grease filters keeps the system at design airflow; clogged filters force the fan to work harder, burning energy

For business owners shopping around, the cheapest-to-buy hood is rarely the cheapest to operate. Ask any supplier for the exhaust fan power draw and rated capture velocity — those tell you running cost and whether the system will actually contain smoke, fume and odour at the cookline.

Installation and Maintenance: Common Compliance Mistakes to Avoid

After watching hundreds of Australian kitchen fitouts go through commissioning, these are the proper installation and maintenance failures that come up again and again — and that show up in regular inspections as costly non-conformances:

• Undersized exhaust — designer used CFM (US units) charts without converting, ended up at 60 % of the AS 1668.2 figure
• Mesh filters instead of baffle filters — common in lower-end imported hoods; non-compliant for heavy-duty service and they let grease particles bypass into the duct
• No make-up air at all — kitchen runs negative, the hood underperforms, gas appliances flame yellow and odour from drains gets sucked into the space
• Hood mounted too high above appliances (over 1.0 m below the ceiling) — capture fails even with correct extract volume, and fume escapes back into the kitchen
• Discharge too close to air intakes or windows — usually a planning condition violation, expensive to retrofit
• Galvanised duct used for grease run — must be 304 stainless under current safety regulations
• Expired AS 1851 fire suppression service — auto-voids insurance and triggers council notices
• Access panels missing or sealed shut — cleaning is impossible, grease and smoke residue build-up accumulates inside the duct, and the fire hazard skyrockets

⚠️ What NEVER to do: Never run a commercial cookline with the suppression system bypassed or "test-disabled" — even briefly during service. Operators have lost their insurance, their venue and in tragic cases their staff doing exactly this.

Frequently Asked Questions

What are the minimum ventilation requirements for a commercial kitchen in Australia?

Australian commercial kitchens are governed by AS 1668.1 and AS 1668.2 along with the NCC. For a Type 1 kitchen with grease-producing cooking, exhaust rates typically sit at 0.4–1.0 m³/s per metre of hood length, with capture velocity of 0.4–0.5 m/s at the hood lip and 20–40 air changes per hour for the room.

How much does a commercial kitchen ventilation system cost in Australia?

A compliant system for a small café runs $15,000–$35,000 installed, covering hood, ductwork, fan, make-up air unit and wet chemical suppression. Large restaurant or hotel kitchens sit between $60,000 and $200,000+. Ventless hoods cost more per unit but save on ducting and roof penetrations.

Do I need fire suppression on my commercial kitchen hood?

Yes — any commercial kitchen exhaust hood with grease-laden cooking must have a wet chemical suppression system meeting AS 4587 and serviced under AS 1851 at six-monthly intervals. Insurance and council approvals are conditional on this.

What is make-up air and why does it matter?

Make-up air is the tempered outdoor air supplied back to replace what the hood extracts, sized at 80–90 % of exhaust volume. Without it the kitchen goes negative-pressure — the hood under-captures, gas appliances flame yellow, exhaust fans burn out early.

What is the difference between AS 1668.1 and AS 1668.2?

AS 1668.1 covers fire and smoke control in mechanical ventilation (dampers, shutdown). AS 1668.2 sets the indoor air quality and exhaust rate requirements. Both apply to every Australian commercial kitchen.

Next Steps

If you are planning a new venue or unsure whether your current ventilation passes a council audit, commission a mechanical engineer to run the AS 1668.2 calculations and stamp drawings, then have a licensed fire technician sign off the suppression to AS 1851.

For the products themselves, browse our commercial hoods and canopies collection — every hood meets the 1.2 mm 304 stainless and baffle-filter requirements of AS 1668.2. Pair this guide with our health inspection checklist, fire safety guide and equipment maintenance schedule for the full compliance picture.