SS 9 covers mechanical ventilation and air conditioning where the Building Code requires it, such as ducted systems, shared toilet extracts, spray booths and cooling towers. Cooling towers need weekly or monthly water testing for bacteria, including Legionella; the IQP inspects microbial control and hygiene to AS/NZS 3666, and any fire or smoke-control functions (such as shutdown on alarm) to AS 1851 Section 13.
At a glance
| Specified system | SS 9 |
| Official name | Mechanical ventilation or air conditioning systems |
| Typical intervals | Weekly, monthly, 3-monthly, 6-monthly and annual (varies by task; see below) |
| Standards often cited | AS/NZS 3666.2, AS/NZS 3666.3, AS/NZS 3666.1, AS 1851-2012, AS/NZS 1668.1, NZS 4303, AS 1668.2, AS/NZS 4114, AS/NZS 3896, AS 4276.3.1 |
| Annual certificate | Form 12A from an IQP, attached to the building warrant of fitness |
What SS 9 covers
- Listed where required by the Building Code; supplying outdoor air where natural ventilation is inadequate; capturing or discharging harmful material or keeping pressure differences; or passing through fire separations, changing mode on a fire signal, or including a combustion appliance.[1]
- Not required if none of the criteria apply and failure would be readily apparent and cause occupant complaints before health or safety is threatened.[1]
- Excluded examples: split units without fresh-air intake, domestic-scale kitchen or toilet extract fans, dust extraction outside the building.[1]
- Industrial cooling towers are not required on a compliance schedule under the Building Act.[1]
Which buildings have it
- Included examples: toilet extract serving multiple facilities; ducted systems; spray booths; pressure-differential systems in hospital theatres, isolation rooms, quarantine facilities and pharmaceutical plants.[1]
- Also: cooling towers or evaporative condensers; smoke-management air handling; boiler-fed systems; electric heaters in air handlers; split units introducing fresh air.[1]
How often it is inspected
| System | Daily | Weekly | Monthly | 3-monthly | 6-monthly | Annual | 2–5 yr |
|---|---|---|---|---|---|---|---|
| SS 9 Mechanical ventilation and air conditioning | no | no |
| Task | Typical frequency | Who |
|---|---|---|
| Cooling towers/evaporative condensers with automatic dosing: Legionella and heterotrophic tests | Monthly | Sampled by the owner's water-treatment contractor; analysed by an IANZ-accredited laboratory[1] |
| Cooling towers/evaporative condensers without automatic dosing: dipslide test | Weekly, plus monthly bacteriological tests | —[1] |
| Notify a Legionella result of 1000 cfu/mL or more to the local Medical Officer of Health (National Public Health Service, Health NZ) | Within 48 hours | —[1] |
| Inspection to AS/NZS 3666.2 and AS 1851 | Template options: 3-monthly/6-monthly/annual, 6-monthly/annual, or annual | IQP[2] |
| Form 12A certificate | Annually | IQP[3] |
| Keep records in on-site log book | 24 months | Owner[3] |
What an inspection typically covers
- System hygiene to AS/NZS 3666.2, with particular attention to Legionella risk in cooling towers and evaporative condensers.[1]
- Chemical control and bacteriological testing of cooling water; dipslide above 10^5 cfu/ml triggers AS/NZS 3666.3 Table 3.2 strategies.[1]
- Fire and smoke control functions (e.g. shutdown on fire signal) to AS 1851.[1]
- Maintenance to keep effective operation and preserve inbuilt safety features.[1]
Standards commonly cited
| Standard | Title |
|---|---|
| AS/NZS 3666.2:2011 | Air-handling and water systems of buildings - Microbial control, Part 2: Operation and maintenance[2] |
| AS/NZS 3666.3:2011 Table 3.2 | Microbial control - chemical control strategies (cooling towers)[3] |
| AS/NZS 3666.1:2011 | Microbial control, Part 1: Design, installation and commissioning[2] |
| AS 1851-2012 (Amdt 1:2016) Section 13 | Routine service of fire protection systems and equipment (fire and smoke control)[2] |
| AS/NZS 1668.1:2015 Section 7 | Fire and smoke control in buildings - shutdown systems[2] |
| NZS 4303:1990 | Ventilation for acceptable indoor air quality[2] |
| AS 1668.2 | Ventilation design for indoor-air contamination control[3] |
| AS/NZS 4114.2:2003 | Spray painting booths (inspection/maintenance)[3] |
| AS/NZS 3896 | Legionella testing method (Handbook Table 1)[1] |
| AS 4276.3.1 | Heterotrophic organisms testing method (Handbook Table 1)[1] |
Titles as listed in council and MBIE documents. Inspections follow the standard and edition named in the building's compliance schedule, usually the edition the system was installed to. Changing to a different edition needs an amendment to the compliance schedule.
Building Code context
- Handbook refers to systems required for the purposes of the Building Code, but names no clause.[1]
- Westland cites Acceptable Solution C/AS2 (for AS/NZS 1668.1 fire and smoke control); no NZBC clause named.[2]
Questions
How often is SS 9 inspected?
MBIE and council guidance shows tasks at these intervals: weekly, monthly, 3-monthly, 6-monthly and annual, with an IQP certifying the system each year. The building's compliance schedule sets the actual frequency.
Which standards apply to SS 9?
Commonly cited: AS/NZS 3666.2, AS/NZS 3666.3, AS/NZS 3666.1, AS 1851-2012, AS/NZS 1668.1, NZS 4303, AS 1668.2, AS/NZS 4114, AS/NZS 3896, AS 4276.3.1. The compliance schedule names the standard and edition for each building.
Who can certify SS 9?
An independently qualified person (IQP) registered with the council for this system. They issue a Form 12A each year, which the owner attaches to the building warrant of fitness.
Sources
- Compliance Schedule Handbook, Amendment 3 — MBIE, 14 February 2014 (first published 25 May 2007)
- Specified Systems Guidance for Customers, WBCA 003 v1.0.1 — Westland District Council BCA, 16 September 2025
- SS 9 Mechanical Ventilation or Air-Conditioning Systems form — Palmerston North City Council / Manawatu DC
General information only, not legal or engineering advice. Last reviewed 30 October 2026. Spotted something out of date? Let us know.
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