Australian Standard
AS 1668 and AS/NZS 1668.2 Compliance for CRAC Rooms
AS 1668 (AS/NZS 1668.2) compliance for CRAC, server rooms and data centres. Ventilation design, outside air, indoor air quality and service checks.
AS 1668, published as AS/NZS 1668.2, is the Australian Standard for mechanical ventilation in buildings. Its full title is "The use of ventilation and air-conditioning in buildings, Part 2: Mechanical ventilation in buildings." The National Construction Code (NCC) calls it up as a deemed-to-satisfy way to provide ventilation and indoor air quality, so it is the reference that drives outdoor air and ventilation design in Australian commercial buildings, including the rooms that house CRAC and precision cooling equipment.
For computer rooms and data halls, the point that confuses people is that CRAC cooling mostly recirculates room air, so it does little ventilation itself. AS/NZS 1668.2 covers the other side: the outdoor (fresh) air for any people who work in or visit the room, the make-up air for any space that runs a mechanical exhaust, the pressure relationship between the room and adjacent spaces, and the ventilation of associated rooms such as UPS battery rooms, generator rooms and fuel stores.
The most safety-critical touchpoint is the battery room. Vented (flooded) lead-acid batteries give off hydrogen, and rooms or enclosures that house them need ventilation sized to keep hydrogen well below its flammable limit. AS/NZS 1668.2 sets out how that ventilation is calculated. Generator rooms, day tanks and bulk fuel stores have their own ventilation provisions in the standard as well.
AS 1668.2 works alongside, not instead of, the other references. AS 1668.1 covers fire and smoke control of the air system. ASHRAE TC 9.9 sets the thermal envelope (temperature and humidity) for the IT equipment. AS/NZS 5149 covers the refrigerant side of DX CRAC units, and AS/NZS 3666 covers the microbial control of any cooling tower or condenser water. AS 1668.2 is the ventilation and outdoor-air piece of that wider picture.
CRAC Services checks the AS 1668 compliance touchpoints during precision cooling design, commissioning and maintenance: the outdoor air strategy, make-up air for exhausted spaces, room pressure relationships, supply and return air paths, ventilation plant condition, battery and generator room ventilation, and how the CRAC room interfaces with the building HVAC system.
Compliance checks
What we check on CRAC sites
01
Confirm whether the room uses dedicated outside air, building HVAC transfer air or sealed recirculation, and that the chosen approach is documented.
02
Check the outdoor air provision for occupants of the room (operators, NOC and control rooms) against the minimum rates in AS/NZS 1668.2.
03
Confirm make-up air is provided wherever a mechanical exhaust runs, so the room is not driven into excess negative pressure.
04
Verify the room-to-room pressure relationship suits the use (for example keeping contaminants or smoke out of the data hall).
05
Check battery room or enclosure ventilation is present and sized for hydrogen dilution where vented lead-acid batteries are installed.
06
Confirm generator room, day tank and fuel store ventilation provisions where standby generation is on site.
07
Check supply and return air paths for blocked grilles, short cycling and hot air recirculation that undermine the design intent.
08
Confirm ventilation fans, dampers, actuators and outdoor air louvres operate and fail to a safe position.
09
Confirm BMS and ventilation alarms are mapped for facilities response.
10
Document any ventilation defect that affects CRAC performance, occupant safety or indoor air quality.
Related services
Services connected to AS/NZS 1668.2
CRAC Maintenance
Preventative CRAC servicing, critical room air conditioning maintenance, quarterly service plans and emergency fault response across all major precision cooling brands.
Cooling Design
End-to-end thermal design for new and brownfield data centres - load calculation, redundancy, airflow modelling, vendor specification.
CRAC Commissioning
ARC-licensed CRAC commissioning, precision cooling commissioning, Site Acceptance Test packs and warranty activation support for new and refit installations.
FAQs
What is AS 1668.2?
AS 1668.2 (published as AS/NZS 1668.2) is the Australian and New Zealand Standard for mechanical ventilation in buildings. It sets the required outdoor air rates for occupied spaces, the ventilation needed for rooms with contaminant sources, make-up air for exhausted spaces, and pressure relationships. The National Construction Code references it as a deemed-to-satisfy way to meet ventilation and indoor air quality requirements.
Does AS/NZS 1668.2 apply to server rooms and data centres?
Yes. Even though CRAC units mostly recirculate room air, AS/NZS 1668.2 still governs the outdoor air for people in the room, the make-up air for any exhausted space, the pressure relationships, and the ventilation of associated rooms such as UPS battery rooms and generator rooms. It is a design and compliance reference for the room, not a CRAC equipment manual.
How does AS 1668.2 apply to UPS battery rooms?
Vented (flooded) lead-acid batteries release hydrogen, which is flammable. AS/NZS 1668.2 sets out how to size ventilation for battery rooms and enclosures so the hydrogen concentration stays well below its lower flammable limit. This is one of the most safety-critical ventilation checks in a data centre, and it sits alongside the cooling design rather than inside it.
Is AS 1668 compliance the same as CRAC maintenance?
No. CRAC maintenance checks the cooling equipment, while AS/NZS 1668.2 compliance checks whether the room ventilation and outdoor air approach is suitable and documented. They need to be reviewed together, because poor ventilation, missing make-up air or wrong pressure relationships can make a correctly serviced CRAC unit underperform, and battery room ventilation is a safety issue in its own right.
How does AS 1668.2 relate to AS 1668.1 and ASHRAE TC 9.9?
They cover different things. AS 1668.2 is mechanical ventilation and outdoor air. AS 1668.1 is fire and smoke control of the air system. ASHRAE TC 9.9 is the thermal envelope (temperature and humidity) for the IT equipment. A compliant data hall design addresses all three: ventilation and outdoor air under AS 1668.2, fire and smoke under AS 1668.1, and the cooling setpoints under ASHRAE TC 9.9.