Compliance & Standards

AS 1668.2, explained

The Australian Standard for mechanical ventilation in buildings, and what it means for commercial kitchen exhaust design and airflow.

The standard

What is AS 1668.2?

AS 1668.2 is the Australian Standard covering the use of mechanical ventilation in buildings: how air should be supplied, moved and discharged so indoor spaces stay healthy and usable. For commercial kitchens, that includes how exhaust hoods and canopies capture heat, smoke and grease-laden air, how ductwork carries it out of the building, where it can safely discharge, and how make-up air replaces what is extracted.

The standard is published by Standards Australia and is referenced by the National Construction Code, so it typically comes into play through building work: new builds, kitchen fit-outs, and alterations to existing systems. How it applies to a specific project is determined by your building surveyor or mechanical services engineer.

Design vs maintenance

Where AS 1668.2 fits alongside AS 1851

The two standards cover different parts of a system’s life. AS 1668.2 is largely about how a ventilation system is designed and installed; AS 1851-2012 is about how fire-related systems are inspected and serviced once they are in use. A kitchen exhaust system designed well under AS 1668.2 still needs routine cleaning and maintenance to keep performing the way it was designed to.

Where SAIS fits: our HVAC build support service advises during design, construction and renovation, informed by AS 1668.2, on things like duct routing, cleaning access and serviceability. Design certification itself sits with your mechanical engineer and building surveyor; we bring the operational and cleaning perspective that is easy to miss on the drawing board.

In practice

What good ventilation design means for your kitchen

  • Capture at the hood. A canopy that captures heat and grease-laden vapour properly keeps the kitchen more comfortable and slows the rate at which grease builds up in the system.
  • Access for cleaning. Systems designed with adequate access panels are far easier to inspect and clean along the full duct run. Missing or inadequate access panels are one of the most common issues we find in the field, and they are much cheaper to design in than to retrofit.
  • Balanced make-up air. Exhausted air has to be replaced. When make-up air is out of balance, doors whistle, exhaust performance drops, and grease can migrate to places it should never reach.

When an existing system has drifted from its design intent, blocked airflow, degraded ductwork, contamination, our system remediation service inspects and brings it back to a serviceable state, and routine duct cleaning keeps airflow performing in line with the way the system was designed.

FAQ

Common questions about AS 1668.2

Is AS 1668.2 mandatory?
It generally applies through the building approval process: the National Construction Code references it, so new builds, fit-outs and alterations are typically required to meet it as part of certification. Whether and how it applies to your specific project is a question for your building surveyor or mechanical services engineer.
What is the difference between AS 1668.2 and AS 1851?
Broadly: AS 1668.2 governs how a ventilation system is designed and installed; AS 1851 governs how fire-related systems, including kitchen exhaust, are inspected and serviced over their working life. A compliant design still needs ongoing maintenance, and good maintenance cannot fully compensate for a poor design.
Does my existing kitchen have to be upgraded to AS 1668.2?
Not automatically. Design standards generally apply when building work happens, so an older system is usually assessed against the rules that applied when it was built, until you alter it. If you are planning a refit, that is the moment the current standard typically comes into play; your building surveyor can confirm what applies.
Can SAIS design or certify a ventilation system?
We do not issue design certification; that sits with mechanical engineers and building surveyors. What we provide through HVAC build support is practical, operationally informed advice during design and construction, on cleaning access, serviceability and the realities of grease management, so the system you build is one that can actually be maintained.
My kitchen has airflow problems. Where do I start?
Start with an inspection. Poor capture, smoke spill or pressure problems can come from grease build-up, damaged ductwork, an unbalanced system or the original design. We assess the system, deal with the cleaning and remediation side, and tell you plainly if the issue looks like one for a mechanical engineer instead.

This page is general information about AS 1668.2, not legal, engineering or regulatory advice. How the standard applies varies by project and building; confirm your obligations with your building surveyor or mechanical services engineer.

Keep reading

Related reading and services

AS 1851-2012, explained AS/NZS 3666.2, explained Our accreditations HVAC build support Kitchen Exhaust Compliance Guide