What AS 1668.2:2024 Means for Air Filtration in Australian Buildings

AS 1668.2:2024 has sharpened the focus on how commercial buildings manage outdoor air, recirculated air and indoor air quality. For facility managers, mechanical contractors and commercial builders, the main takeaway is clear: filtration is not an afterthought, but part of the building’s ventilation strategy and equipment selection.

The standard does not replace good design judgement, and it does not remove the need to confirm site-specific requirements with the mechanical services engineer or building owner. But it does make it more important to choose filters that suit the system, the occupancy and the local dust load, then maintain them properly over time.

Why the updated standard matters to filtration

AS 1668.2:2024 sits within the ventilation framework for Australian buildings, so its impact on filtration is practical rather than abstract. In many commercial systems, filtration affects what enters the occupied space, how clean recirculated air remains, and how quickly dust builds up across coils, fans and ductwork.

That means filtration is part of three linked decisions:

• •what air is brought into the building
• •how much of that air is filtered before supply
• •how the system is maintained once it is operating

If a building has changed use, tenant density or operational hours, the original filter arrangement may no longer be the best fit. A filter that once suited a low-dust tenancy may not suit a site with higher outdoor contamination, loading dock traffic, nearby construction or heavier internal particulate load.

For that reason, it is worth reviewing both the ventilation design intent and the filtration equipment actually installed. If you need help identifying what is in place, how to measure an air filter is a useful place to start.

What AS 1668.2:2024 means in practical terms

The standard reinforces the idea that ventilation performance depends on the whole system, not just fan capacity or airflow rates. Filtration becomes more relevant where outdoor air is brought in, where recirculation is used, or where the building needs better control of dust and debris entering occupied areas.

In practice, this means facilities teams should look at:

• •the type of air being introduced to the system
• •whether pre-filtration and final filtration are both needed
• •the pressure drop across the filter bank
• •how accessible the filters are for inspection and changeout
• •whether the system can physically accept a higher performance filter without compromising airflow

If the system was designed around a specific filter class or arrangement, replacing it with a different product without checking pressure drop and frame dimensions can create problems. A denser filter is not automatically better if the fan and ductwork were not designed for it.

If the building owner, engineer or contractor is updating an older system, it may also be worth reviewing whether a standard off-the-shelf filter is suitable or whether custom air filters are needed to match the plant.

Choosing the right filter for the job

There is no single filter grade that suits every commercial building. The right selection depends on the system design, indoor use, outdoor environment and maintenance access.

Common considerations include:

• •Particle load: Sites near busy roads, car parks, workshops, loading areas or active construction may need more robust filtration.
• •System sensitivity: Some HVAC systems can accommodate a higher efficiency filter more easily than others.
• •Space constraints: Filter depth, frame style and access space all affect what can be installed.
• •Maintenance access: If access is awkward, the best filter on paper may not be the most practical in service.
• •End use: Offices, retail, education, hospitality, healthcare and industrial spaces all present different demands.

In Australia, people still often refer to older EN 779 classes such as G3, G4 and F5-F9. These are still widely used terms, even though ISO 16890 is now the current classification system in many contexts. MERV, EN 779 and ISO 16890 do not convert directly, so it is safer to compare filter performance within the same standard rather than assume an equivalent match.

For some applications, HEPA filtration may be relevant. Under EN 1822, H13 filters have an efficiency of at least 99.95% at the most penetrating particle size, while H14 filters have at least 99.995% at the most penetrating particle size. Those grades are only appropriate where the system design and site requirements call for them.

Maintenance, inspection and pressure drop

A filter only performs as intended if it is monitored and maintained properly. AS 1668.2:2024 puts more weight on operational reality, which means inspection and replacement planning matter as much as initial selection.

Do not rely on a fixed calendar approach alone. Inspection frequency depends on the system, site conditions and dust load. Follow the filter and equipment manufacturer instructions, and check pressure drop where gauges are fitted.

That approach helps you:

• •spot loading before airflow is affected
• •avoid unnecessary changeouts
• •keep records that support maintenance planning
• •identify whether a site needs a different pre-filter or final filter arrangement

If your team handles ongoing upkeep, commercial filter servicing can help keep inspection and replacement work consistent across multiple assets.

Washable and reusable products

Some filters are designed to be washable, but not all of them are. If a product is intended to be reused, follow the product instructions carefully and confirm whether washing affects performance, fit or service life.

This is especially important in commercial settings where staff may assume all filters can be cleaned and returned to service. In reality, washability is a property of specific products, not a general feature of all filters.

What builders and contractors should check during design and handover

For builders and mechanical contractors, the main challenge is making sure the installed filtration arrangement matches the design intent and is practical to maintain after handover.

Before finalising a system, check:

• •filter dimensions and access clearances
• •whether the frame, tracks and sealing arrangement suit the chosen filter type
• •whether the fan can handle the expected pressure drop
• •whether the maintenance team can inspect and replace filters safely
• •whether the project documentation clearly states the filter specification

This is also a good time to confirm the intended use of the space with the mechanical services engineer or building owner. A tenancy fitout, plant replacement or change of occupancy may alter filtration needs even if the ductwork stays the same.

Good handover documentation should make it easy for the facilities team to identify the installed filter, order replacements and understand any special handling requirements. If you are updating a site or ordering replacements, our products page is a useful place to review the range.

When to seek advice on a site-specific solution

If a building has persistent dust issues, a difficult filter access arrangement or non-standard plant, a tailored solution may be the most practical option. This is often the case when dimensions, sealing, airflow or maintenance access do not suit a standard catalogue product.

Useful times to review the filtration arrangement include:

• •when upgrading older HVAC equipment
• •when changing a building’s use or occupancy profile
• •when a site sits in a high-dust or high-traffic location
• •when the current filter arrangement is difficult to service
• •when the existing product is no longer available or no longer fits correctly

If you are unsure what filter type, size or arrangement you need, speak with a supplier who can work from measurements and system details rather than guesswork. A quick site review or accurate measurements can save a lot of back-and-forth later.

How Total Air Filtration can help

Total Air Filtration is a family-owned air filter manufacturer and supplier in Hillcrest, Brisbane QLD, and we work with commercial clients who need the right filter for the right system. We can supply standard products or make custom air filters to suit specific equipment and site requirements.

If you need help matching a filter to AS 1668.2:2024-related project requirements, or you want to discuss a replacement for an existing system, call 07 3800 3448 or request a quote.

You can also contact us if you need help identifying a filter, planning a service visit or confirming what will suit your building.