If you own or operate a restaurant, café, pub kitchen, or aged-care facility in Sydney, there is a good chance someone has mentioned AS 1668 to you, probably a certifier, a council inspector, or an insurance broker asking awkward questions after a claim. It is not the most exciting topic in hospitality, but getting it wrong can cost you your occupancy certificate, your insurance cover, or in the worst case, the kitchen itself.
Here is what AS 1668 actually is, what it requires of a commercial kitchen, and the compliance gaps we see most often when we are called out to inspect ageing exhaust systems across Sydney Metro and Wollongong.
What AS 1668 Actually Covers
AS 1668 is the Australian Standard for the use of mechanical ventilation and air-conditioning in buildings. It is referenced directly by the National Construction Code (NCC), which means compliance is not optional, it is the law for any building where mechanical ventilation is required.
The standard is published in several parts. Two of them matter most for a commercial kitchen:
- AS 1668.1 governs fire and smoke control. In a kitchen context, this is about the fire-resistant construction of the exhaust riser, fire dampers, and how the exhaust system behaves during a fire so it does not spread flames through the building.
- AS 1668.2 governs mechanical ventilation design for contaminant control. This is where commercial cooking processes are covered specifically, the airflow rates your canopy must achieve, how makeup air is supplied, grease filter requirements, and the design of the exhaust system as a whole.
If the building has a residential floor above the kitchen, or if the exhaust discharge is near a neighbour's window or air intake, the bar gets higher again.
What This Means in Practice
For an operator, AS 1668 compliance translates into four concrete requirements:
- Adequate capture and containment at the canopy. The exhaust has to pull all the smoke, grease, and heat from the cooking surface out of the room. This depends on canopy size, overhang, and the exhaust fan's extract rate.
- Fire-rated ductwork through any floor it passes through. Grease-laden exhaust in a non-fire-rated duct is one of the most common causes of serious commercial kitchen fires.
- Proper makeup air. If you are extracting air, you need to replace it, otherwise the kitchen goes into negative pressure, back-draws from other vents, and staff cop every smell in the building.
- Certified discharge location. The exhaust cannot discharge into a courtyard, near an operable window, or near fresh-air intakes for the building's HVAC.
Each of these is measurable and inspectable. Most compliance failures are not mysterious, they come down to something visible that was compromised during fit-out, or something that has degraded over years of service.
The Five Compliance Failures We See Most Often
After 15+ years in commercial kitchen ventilation across Sydney, the same issues keep recurring:
1. Undersized exhaust fans for the cooking load. A kitchen starts with two fryers and ends up with a char-grill and a wok burner five years later, but the exhaust fan was never upgraded. The canopy can no longer capture the plume, and grease condenses in the ductwork instead of being pulled out.
2. Missing or bypassed fire dampers. Dampers get pinned open during a renovation and never get reset. Sometimes they were simply never installed. Either way, the first time the kitchen catches fire, the exhaust riser becomes a chimney for the building above.
3. Grease filters cleaned but ductwork neglected. Operators clean the baffle filters weekly because they are visible. The duct behind the canopy has not been cleaned in years and is carrying a thick layer of combustible grease. AS 1851 requires scheduled duct cleaning, your insurer will ask for evidence of it after any incident.
4. Makeup air shortcuts. The contractor "solved" a pressure problem by leaving the back door propped open. This technically works until council, a health inspector, or an auditor walks past.
5. Exhaust discharge too close to an air intake or window. A common issue in strata buildings or older shopping-centre tenancies where the original design got overridden during a subsequent fit-out.
What Compliance Looks Like on Paper
If council, your insurer, or a building surveyor asks for proof of compliance, they will expect to see:
- A mechanical certificate of installation for the exhaust system, completed by a qualified tradesperson against AS 1668.1 and AS 1668.2.
- Annual baseline data showing extract airflow has been measured and is within design specification.
- A maintenance log aligned with AS 1851, covering filter cleaning, duct cleaning, and any fire-damper testing.
- The original design documentation if the system was installed or upgraded recently.
If any of those are missing, you are exposed. In an insurance dispute, the absence of records is often treated the same as non-compliance.
How to Get Ahead of It
You do not have to rebuild the kitchen to get compliant. In most cases, a site inspection from a licensed mechanical electrician will tell you within a couple of hours exactly where you stand. From there, it is usually a prioritised list of fixes rather than a total rebuild, a fan upgrade here, a damper reinstatement there, a duct clean and a paper trail to close out the rest.
At Altruism NSW we do AS 1668 inspection and certification as a standalone service, as part of a scheduled maintenance agreement, or bundled into an installation. If you are not sure where your kitchen stands, it is cheaper to find out on a Tuesday than during an incident.
Book a compliance inspection: call us on 0423 063 061 or request a quote through the contact page. $0 call-out across Sydney Metro and Wollongong.
This article is general information, not legal or engineering advice. For a specific determination, have your site inspected by a qualified mechanical electrician and, where required, a building surveyor.