AS 1668.2:2024 and Filter Selection for Australian Commercial Buildings

AS 1668.2:2024 is a key reference point in Australian commercial ventilation projects, but it does not sit in isolation. The standard influences how a building is ventilated, how air passes through the system, and which filters are practical for the application. For facility managers, mechanical contractors and builders, the main task is to match the filter arrangement to the system intent, the site conditions and the project brief.

At Total Air Filtration, a family-owned air filter manufacturer and supplier in Hillcrest, Brisbane QLD, we regularly help teams work through those decisions. The right filter is not just about size and fit. It is about airflow, pressure drop, maintenance access, indoor environment goals and the requirements agreed with the mechanical services engineer or building owner.

Why AS 1668.2:2024 matters when selecting filters

AS 1668.2:2024 covers ventilation requirements for Australian buildings, so it has a direct bearing on how the air handling system is designed and operated. In practice, that means filter choice should be considered early, not treated as an afterthought once the system is already specified.

The standard can affect:

• •the amount of outside air brought into the building
• •the way supply air is treated before it reaches occupied areas
• •whether pre-filtration, final filtration or both are needed
• •fan selection and available static pressure
• •access for inspection, cleaning and replacement

A filter that looks suitable on paper may not suit the system if it creates too much resistance, does not fit the available space, or is difficult to inspect safely. That is why filter selection should be discussed alongside ventilation design, rather than separately.

How filter choice affects ventilation design

Filters do more than remove visible dust. They also influence how the whole ventilation system behaves. A higher efficiency filter may improve particle capture, but it can also increase resistance to airflow. If the fan, ductwork or fan speed control has not been designed with that in mind, the system may not perform as intended.

Points engineers and contractors often need to confirm

• •whether the system is a simple supply arrangement or part of a more complex air handling setup
• •whether pre-filters are used to protect final filters and reduce loading on the finer stage
• •the available filter depth and frame type in the cabinet or duct section
• •whether bag, panel, pleated or cartridge-style filters are appropriate for the application
• •whether the system allows for pressure monitoring across the filter bank

Where a pressure gauge or differential pressure monitor is fitted, it is useful for tracking loading over time. Inspection frequency depends on the system, site conditions and dust load, so it is better to monitor the installation than to rely on a generic schedule. Always follow the filter and equipment manufacturer instructions.

If you need help matching filter dimensions or styles to existing equipment, our how to measure an air filter guide is a practical starting point.

Choosing the right filtration level for the application

There is no one-size-fits-all answer. The right filter depends on the building type, the ventilation strategy and the level of particle control needed. Offices, retail spaces, education buildings, hospitals, food areas and industrial or dusty sites often call for different filter arrangements.

In Australian projects, you may see a mix of rating systems on product literature or older specifications. MERV, EN 779 and ISO 16890 do not convert directly, so they should not be treated as interchangeable. EN 779 classes such as G3, G4 and F5 to F9 are still widely used in Australia, even though ISO 16890 has superseded EN 779 in many contexts.

For some applications, a coarse pre-filter may be enough ahead of a finer final stage. In other projects, a higher efficiency arrangement may be specified because the system design or building use calls for it. The important point is to confirm the requirement with the mechanical services engineer or building owner before selecting product.

HEPA filters are a separate category again. Under EN 1822, H13 filters are at least 99.95% efficient and H14 filters are at least 99.995% efficient at the most penetrating particle size. Those products are used where very high filtration performance is required, but they are not appropriate for every commercial building system.

Practical compliance discussions on site

A good compliance conversation is not just about whether a filter has a label on it. It is about whether the installed system matches the design intent, the project documentation and the building’s operating conditions.

Facility managers and contractors usually need to check:

• •whether the installed filter matches the specified size, depth and frame arrangement
• •whether the airflow direction is correct
• •whether the filter bank seals properly to avoid bypass
• •whether there is access for inspection and replacement
• •whether the system can tolerate the pressure drop of the chosen filter stage
• •whether the selected product suits the site’s dust load and operating hours

If there is uncertainty, it is worth resolving it early. That can prevent delays during commissioning, handover or routine maintenance. It also helps avoid situations where a filter is technically suitable but awkward to maintain in the actual plant room or ceiling space.

If the project involves a unique cabinet size, non-standard frame or a legacy system, custom air filters can be a practical option.

Maintenance, replacement and washable products

Long-term performance depends on maintenance as much as selection. A well-chosen filter still needs regular inspection, and the inspection interval will vary by site conditions, dust loading and system design. Where available, pressure drop readings are the most useful guide to when attention is needed.

A few maintenance points to keep in mind:

• •do not assume the same filter will suit every application in the building
• •check seals, frames and gaskets as well as the media itself
• •replace damaged or collapsed filters promptly
• •keep spare filters correctly stored so they are not contaminated before installation
• •make sure maintenance staff know the correct direction of airflow and fitment method

Some filters are designed to be washable. Check the product instructions before cleaning or reusing any filter, because washability is a property of specific products rather than a general rule.

For ongoing support, our filter servicing and commercial filter servicing pages explain how we can assist with supply and maintenance planning.

Working with the right supplier helps keep the project moving

AS 1668.2:2024 sets the framework, but every building still needs a practical filtration solution that suits the system, the site and the maintenance plan. That is where detailed product advice, correct measuring and prompt supply make a real difference.

Total Air Filtration can supply standard commercial filters or make the right filters for unusual sizes and applications. If you are working through a ventilation design, replacement program or compliance discussion, call 07 3800 3448 or request a quote. You can also contact us or browse our products to find the right fit for your building.