How to Specify Filters for Body Corporate Common Area Air Conditioning

Body corporate common areas ask a lot of an air conditioning system. Foyers, lift lobbies and corridors often run for long hours, see frequent door openings, and need filters that fit properly, seal well and can be changed without creating unnecessary disruption.

If you are specifying replacement filters for a strata building, the main job is not just choosing a rating. It is making sure the filter matches the unit, the access arrangement and the building’s maintenance routine so the system stays practical to service.

Start with the system, not the filter

Before ordering anything, identify exactly what type of equipment serves the common area.

In many buildings, foyer and corridor air conditioning is part of a fan coil unit, package unit, ducted system or make-up air arrangement. The same building may have more than one unit size or filter style, so it is worth checking each location separately.

Useful details to confirm include:

• •the unit make and model, if available
• •the filter frame size and depth
• •whether the filter slides into a rack, cassette or side access slot
• •whether there is enough clearance to remove the filter without bending it
• •whether the filter sits before or after the fan
• •whether the unit has a pressure gauge or differential pressure port

If the existing filter is damaged, warped or missing a label, how to measure an air filter is a good starting point.

If the building manager is unsure what the unit needs, the safest path is to check the equipment manual and confirm site requirements with the mechanical services engineer or building owner, especially where AS 1668.2:2024 may be relevant to the ventilation system design.

Choose a filter that suits the space

For common area systems, the best filter is usually the one that balances dust capture, airflow and ease of access. A tighter filter is not always a better filter if the system was not designed for it.

Foyer systems

Foyers tend to collect outdoor dust, litter fibres and general building traffic debris. A well-fitting panel or pleated filter is often used in these areas, depending on the unit design.

Look for:

• •a rigid frame that holds its shape during installation
• •a media type suited to the system airflow
• •edges that seal properly in the holder so air does not bypass the filter
• •enough surface area to avoid excessive restriction where the unit has limited fan capacity

Lift lobby and corridor systems

Lift lobbies and corridors often have long, narrow duct runs or smaller return air paths. These spaces can be difficult to service if the filter is tucked above a ceiling or behind a locked access panel.

In these settings, it helps to specify filters that are:

• •easy to identify at a glance
• •simple to remove and reinstall correctly
• •stable enough to resist distortion in tight frames
• •available in a consistent size so replacements match the original fit

If the building uses custom dimensions, custom air filters may be the most practical option.

When filtration level matters

Some buildings need finer filtration than a basic dust filter, particularly where the system serves a more enclosed or high-traffic common area. Filter ratings are helpful, but they are not directly interchangeable between rating systems.

MERV, EN 779 and ISO 16890 do not convert directly, so avoid relying on rough equivalence charts when ordering. In Australia, G3/G4/F5-F9 are still commonly used EN 779 class references, although ISO 16890 is now the current standard framework.

If a project requires higher-efficiency filtration, the specification should be set to suit the equipment and the intended application. For very high-efficiency needs, HEPA filters are a different category again: H13 is at least 99.95% and H14 is at least 99.995% efficient at the most penetrating particle size under EN 1822.

Fit and access are just as important as the rating

A filter that looks right on paper can still cause problems if it is awkward to install or does not seal properly. In strata common areas, access is often the deciding factor.

Check the opening before you buy

Measure the actual filter slot, not just the old filter, because damaged or compressed frames can give a false reading. Check:

• •length, width and depth
• •direction of airflow
• •frame lip or gasket style
• •whether the access door opens fully
• •whether there is enough room to extract the filter without damaging ceiling tiles or insulation

When a filter must be forced into place, it may distort, bypass air or make future servicing harder. A small change to the frame depth or rigidity can make a big difference to maintenance access.

Think about who will service it

In a body corporate setting, the person changing the filter may be a contractor, building manager or maintenance crew member who needs a fast, repeatable process. Good filter specification should reduce guesswork.

That usually means:

• •clear labelling on the frame or media
• •consistent orientation marks
• •a simple path for insertion and removal
• •sturdy packaging that protects the filter before installation

If a system is particularly awkward, it may be worth discussing the servicing method as well as the filter itself. filter servicing and commercial filter servicing can help keep the process organised.

Decide whether standard or custom sizing is better

Standard sizes are convenient when the equipment was designed for them and the existing frame is in good condition. But common area systems are often modified over time, and the original filter may no longer be the best fit.

Custom sizing is often worth considering when:

• •the filter opening is an odd size
• •there is leakage around the edges of the current filter
• •the frame has been altered or repaired
• •the unit is located in a confined ceiling space
• •the building wants one consistent specification across several similar units

Custom filters can also be useful where the goal is to improve fit without replacing the whole air handling unit. The key is to measure carefully and confirm the orientation, depth and sealing method before ordering.

If you are unsure whether a standard or custom option will work best, our products and custom air filters are a practical place to compare options.

Build the maintenance plan into the specification

A filter specification should include more than the product code. For strata common areas, it should also describe how the filter will be inspected and replaced over time.

Inspection frequency depends on the system, site conditions and dust load. Follow the filter and equipment manufacturer instructions, and monitor pressure drop where gauges are fitted. Where access is difficult, it is worth keeping the replacement method simple and the filter specification consistent so servicing stays straightforward.

Some filters are designed to be washable - check the product instructions before assuming a washable option is suitable. If the building prefers reusable filters, confirm how they should be cleaned, dried and refitted so the system is not compromised by incorrect handling.

It also helps to keep a record of:

• •filter size and type
• •location served, such as foyer or corridor
• •access method and any special tools needed
• •supplier details for repeat ordering

That record reduces confusion when multiple units in the same building use similar but not identical filters.

What to send when requesting a quote

If you want the right filter first time, provide as much detail as possible.

Include:

• •the unit model or a clear photo of the filter bay
• •exact dimensions of the current filter, or the opening size if the old filter is missing
• •the number of filters required
• •the location served, such as foyer, lift lobby or corridor
• •any access issues, including ceiling height or locked panels
• •whether you need standard or custom sizing

The more precise the information, the easier it is to match the filter to the system and avoid back-and-forth on site.

Talk to Total Air Filtration

Total Air Filtration is a family-owned air filter manufacturer and supplier in Hillcrest, Brisbane QLD, and we can help you select or make the right filters for your common area system.

If you are managing a foyer, lift lobby or corridor installation and need advice on fit, access or sizing, call 07 3800 3448 or request a quote.

You can also browse our products or contact us if you need help confirming what your building needs.