What is AS 1668.2:2024

AS 1668.2:2024—titled ‘The use of ventilation and air conditioning in buildings Mechanical ventilation in buildings'—is the primary Australian Standard for setting minimum design guidelines determining ventilation rates for general application in buildings. It is a rigorous standard that helps guide the design, performance, and installation of mechanical ventilation systems.

AS 1668.2 was released in 2024 and has become a critical compliance measure for adhering to the National Construction Code (NCC). This makes it essential for HVAC engineers, mechanical designers, building services designers and compliance officers.

With a growing focus and a new understanding of indoor air quality and energy-efficient systems, understanding AS 1668.2:2024 (along with its companion part AS 1668.1) is critical for modern building design.

In this article, we cover why AS 1668.2:2024 matters, what it covers, how to apply or get the standard and how organisations can implement it in the workplace.

AS 1668.2:2024 plays an important role in creating a healthy, safe and compliant indoor environment. According to the Department of Climate Change, Energy, the Environment and Water, Australians spend approximately 90% of their time indoors. This makes an effective ventilation system critical to control indoor air quality and the associated health risks.

With a new understanding of the role poor ventilation plays in health, mechanical ventilation is now a core component of modern building practices. In particular, these three core benefits include:

• Compliance: The 1668.2 standard is not just optional, as new building types and construction must adopt it to meet compliance obligations with the National Construction Code (NCC). This means NCC-regulated building projects must meet this standard, and a failure to do so could result in legal and compliance consequences.

• Ensuring Indoor Air Quality: The standard establishes the minimum air supply rates needed to maintain acceptable indoor air quality.  Importantly, it also helps to address new technologies such as HVAC systems in offices, commercial buildings, residential homes and healthcare and educational facilities to maintain correct airflow.

• Safety & Risk Reduction: 1668.2 helps to prevent hazards in critical high-risk environments, such as in carparks, kitchen exhausts, borrowed ventilation (enclosed rooms) and chemical exposure in plant or storage areas.

There is real harm associated with poor air ventilation—RMIT found that higher concentrations of CO2 indoors have been linked to reduced cognitive performance and other negative health effects.

Understanding 1668.2 is therefore not just a ‘nice to have’ but an essential standard. In the workplace, HVAC engineers, mechanical designers, building services designers, and compliance officers must consider AS 1668 when building projects, and failing to do so could pose serious problems for organisations and impact the health of the wider public.

The AS 1668.2:2024 standard provides detailed requirements for mechanical ventilation systems across a range of building types. This includes the outdoor air flow calculator, carpark ventilation, kitchen exhaust, and borrowed ventilation concepts.

Specifically, there are 5 main sections in AS 1668.2:2024, these include:

Section 1—Scope & General: Defines the selection and application of mechanical ventilation that will be covered. This excludes natural ventilation, which is covered in Part 4.

Section 2—Mechanical Ventilation—Supply Systems: Focuses on single and multi enclosure systems, setting minimum standards for air flow rates and air-handling procedures.

Section 3—Mechanical ventilation—Exhaust Systems: Focuses on the impact and general requirements of exhaust systems found in environments such as kitchens.

Section 4—Mechanical Ventilation of Enclosures Used by Vehicles With Combustion Engines: Focuses on the impact of airflow in car parks and in other enclosed places where ventilation is required.

Section 5—Mechanical Ventilation of Enclosures Used for Particular Health Care Functions: Focuses on ventilation inside residential care, hospitals and healthcare facilities.

The AS 1668 series has a long history in Australian building design, with multiple changes, adaptations and revisions over the years.

• AS 1668.2-1976: The first publication formalised minimum ventilation performance for modern buildings.
• AS 1668.2-1980: The first revision introduced more requirements for mechanical ventilation performance in buildings and defined design parameters.
• AS 1668.2-1991: Expanded its scope and introduced new calculations to inform ventilation guidelines.
• AS 1668.2-2002: Began to be informally integrated with NCC requirements to become a part of building best practices.
• AS 1668.2-2012 (5th edition): Widely used until it was superseded by the 2024 version. It included a new approach to carpark and kitchen ventilation and more general ventilation requirements.
• AS 1668.2:2024 (6th edition & most current): The latest edition saw a host of new updates to reflect current engineering practices and technology, such as quantified performance requirements, enhanced calculation methods, and updates to carpark or kitchen ventilation.

The series has a rich history, with many updates—it’s therefore important to stay across the standard for any new revisions that are likely to take place. Intertek experts help to inform current standard holders and signal any changes or updates that are required to remain compliant.

Understanding and obtaining the AS 1668.2:2024 standard is just the start. There’s a host of practical ways HVAC engineers, mechanical designers, building services designers, and compliance officers can practically apply the standard:

• Determine Outdoor Airflows: The revised edition helps to quantify performance requirements by providing clearer and measurable ways to calculate correct ventilation. For example, new methods help to inform variable occupancy or better load modelling, making determining outdoor easier and more consistent.

• Determine “Borrowed Ventilation”: There are more explicit limitations, design requirements, and calculations that specifically address health outcomes and risk. The new edition provides acceptable room types where borrowed ventilation may apply or required airflow directions to manage borrowed ventilation.

• Use Updated Car Park Ventilation Guides: The 2012 and 2024 editions provided practical insights, such as revised airflow rates or clearer pollutant sensor strategies to guide decision-making. 

• Integrate With Mechanical Ventilation Systems: AS 1668.2:2024 suggests practical considerations to cohesively integrate HVAC systems, such as ensuring pressure differentials in critical areas, supporting energy efficiency requirements or coordinating with outdoor air supply with air conditioning systems.

• Audit and Verify Ongoing Compliance: Use the standards maintenance and inspection documentation to systematically check that installed ventilation systems maintain the required airflow rates as per their specific circumstance or environment.

By applying these calculations, suggestions and guides for kitchen and outdoor or borrow ventilation airflows, it not only provides a safer and healthier environment but also means organisations are compliant with important NCC requirements.

The latest official edition of AS/NZS 1668:2024 (The use of ventilation and air conditioning in buildings, Mechanical ventilation in buildings) is available directly from Intertek Inform.

Intertek Inform is a trusted source for official standards and technical publications across many industries. 

Pricing for AS/NZS 1668:2024 starts at $296 for a single-user PDF, with a hard copy starting at $329. Prices change depending on the number of users, with higher savings for multi-user PDFs.

When you purchase AS 1668.2:2024 through Intertek Inform, users will benefit from:

• Genuine Standards: A trusted and authentic copy direct from Standards Australia
• Immediate Access: Instant PDF downloads with verified licensing
• Multiple Formats: Choose from PDFs, hard copies, or discounted bundles.
• Expert Support: Access to Intertek’s global network of quality and compliance specialists who help you stay compliant

Intertek Inform provides reliable, genuine and updated access to the important standards to get you and your employees safe and compliant.

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