Public Aquatic Centre & Olympic Pool HVAC Ductwork — Council, Competition & Brisbane 2032 Venues

Why public aquatic centres are a different ductwork problem

A municipal aquatic centre is not a bigger hotel pool. The bather load, the operating hours, the spectator capacity, the chemical inventory and the regulatory exposure are all an order of magnitude higher than a hotel basement lap pool or a suburban learn-to-swim school. A 25 m council pool typically processes 200,000 to 400,000 visitor sessions per year. A regional Olympic-standard 50 m venue with a hydrotherapy pool, learn-to-swim tank, splash deck, gym suite and spectator gallery can run 800,000 to 1.5 million annual sessions. Every one of those bathers contributes urea, perspiration and dermal organics that combine with chlorine to form chloramines — the same chloramines that destroy unsuitable ductwork in three to seven years and trigger the recurring renovation cycle so familiar to council facility managers across Sydney, Melbourne, Brisbane and Perth.

This guide sits alongside our existing indoor-pool aquatic centre guide, which deals with hotel, private and learn-to-swim facilities. Here we focus on the commercial-scale council facility and the Olympic-pipeline competition venue: how the codes apply at scale, how zoning multiplies, how material selection sharpens, and how the Brisbane 2032 venue pipeline is reshaping aquatic ductwork specifications across the Australian eastern seaboard.

It is written for facility managers commissioning a refurbishment, mechanical consultants drafting a tender, council asset planners writing a 25-year capital pipeline, and ductwork fabricators bidding into the aquatic vertical. Every reference is to an Australian standard, an ASHRAE document or a FINA technical rule — there is no in-house guidance dressed up as code. The intent is that you can lift figures, zoning logic and material specifications straight into a design report and stand behind every number.

The standards stack that applies to a council aquatic centre

A municipal aquatic centre is regulated under a stack of overlapping documents. None of them is sufficient on its own. The competent design integrates all of them — and the procurement contract should require the contractor to evidence compliance with each.

ASHRAE 62.1 — Ventilation for Acceptable Indoor Air Quality

ASHRAE 62.1 (currently 62.1-2022 with 62.1-2025 in committee) is the international baseline for indoor air quality in mechanically ventilated buildings, including natatoriums. In Australia it does not have the force of law, but it is referenced extensively in mechanical consultant scopes and is functionally a benchmark used in every council tender we see for aquatic refurbishments. The natatorium classification falls under occupancy category 4 — pool and spa areas — with a minimum outdoor air rate of 2.4 L/s per square metre of water surface for the pool deck zone alone. Most Australian designs run higher to account for chloramine dilution.

ASHRAE Applications Handbook Chapter 6 — Indoor Swimming Pools

The single most useful document for natatorium design is Chapter 6 of the ASHRAE Applications Handbook. It is not a code in the strict sense — it is a design reference — but it is the document mechanical consultants turn to when working out air flow patterns, evaporation rate calculations, dehumidification load and chloramine capture strategy. Chapter 6 sets out the recommendation that air temperature should run 1 to 2 degrees Celsius above water temperature with relative humidity controlled between 50 and 60 percent; it provides the standard evaporation rate equation (variants of the Smith equation and the ASHRAE 2019 update) and discusses surface skim duct geometry for chloramine capture. Anyone designing aquatic HVAC without a copy of Chapter 6 on the desk is operating without instruments.

AS 1668.2 — The use of ventilation and airconditioning in buildings (Australia)

AS 1668.2 is the Australian code that governs ventilation rates in any mechanically ventilated building, including indoor pools. The most relevant figure is the pool surface ventilation rate of 6 L/s per square metre of water surface (V_a = 6 L/s/m2). This is higher than the ASHRAE 62.1 minimum and reflects the Australian regulator's preference for stronger chloramine dilution. For a FINA-standard 50 m × 25 m competition pool with 1,250 m2 of water surface, AS 1668.2 establishes a minimum outdoor air rate of 7,500 L/s — and that is before adding spectator gallery occupant ventilation, change room exhaust, plant deck purge or fitness-suite occupant load.

AS/NZS 1838 — Swimming pool water treatment

AS/NZS 1838 governs the chemistry side of pool operation — chlorine residual, pH range, cyanuric acid limits, and the testing regime. It is not a ductwork standard directly, but mechanical engineers should read it because the chemistry assumptions in 1838 (combined chlorine residual, pH 7.2 to 7.8, free chlorine 1 to 3 mg/L) drive the chloramine generation rate at the water surface, which in turn drives the ductwork exposure level. A facility running at the top of the 1838 chlorine band with high bather load is a more aggressive ductwork environment than a facility running mid-band — and the material selection should reflect it.

AS/NZS 3666 — Air-handling and water systems of buildings: Microbial control

AS/NZS 3666 (parts 1, 2 and 3) is the Australian Legionella control standard. It applies to every cooling tower, evaporative condenser and warm water system in an aquatic centre — and many council facilities still operate evaporative cooling towers for chiller heat rejection. The standard requires a documented risk management plan, registration with the local public health authority, monthly inspection records, six-monthly chemical cleaning, biocide dosing logs and Legionella sampling at prescribed intervals. The ductwork question is downstream — return air from a pool hall passing close to a cooling tower plume needs particulate filtration upgrades — but the AS/NZS 3666 management regime is non-negotiable and must be flagged at design stage.

AS 4575 — Domestic gas burning appliances (servicing requirements)

AS 4575 deals with gas appliance servicing, and we reference it here because most aquatic centre wet plant decks include gas-fired pool heating, gas-fired pool hall heating, or both. The standard sets out the inspection regime for flue, combustion air and gas line integrity that the HVAC designer must coordinate with — particularly when combustion air intakes share a wall with pool hall outside air intakes, which is a common spatial conflict in retrofits.

FINA / World Aquatics facility rules

FINA (renamed World Aquatics in 2022) sets the technical rules for competition pool dimensions, depth, lane width, water temperature for elite competition, lighting and timing systems. For HVAC engineers the relevant figures are: 50 m × 25 m × 3 m minimum depth for an Olympic-standard pool with eight lanes; water temperature 25 to 28 degrees Celsius for competition (typically 27 degrees C is targeted); spectator capacity influencing the AHU zoning for the gallery. World Aquatics does not specify ductwork material, but the FINA dimensions drive the air volume calculations and the hall geometry which in turn drives ductwork routing.

AS/NZS 4254.1 and 4254.2 — Ductwork for air-handling systems in buildings

AS/NZS 4254 (parts 1 flexible duct and 2 rigid duct) is the Australian-New Zealand ductwork construction standard. It governs gauge, seam type, support spacing, leakage class and pressure class for every fabricated duct system in Australia. For aquatic centres the relevant choices are leakage Class C (low pressure) for general pool hall supply and Class A (sealed seam) for chloramine return paths.

SMACNA HVAC Duct Construction Standards

SMACNA (Sheet Metal and Air Conditioning Contractors National Association) is the US equivalent of AS/NZS 4254 and is heavily referenced in international tender documents. For Olympic venues with overseas mechanical consultants — and that applies to most of the Brisbane 2032 pipeline — SMACNA tolerance tables for length, width and squareness are usually written into the specification. SBKJ ductwork machines are tested against both AS/NZS 4254 and SMACNA tolerances out of the box.

How the codes combine at the pool deck

The integration of the standards stack above produces a deck-level design envelope that any mechanical consultant should be able to back-calculate from a project brief. We work through it below for a typical regional Olympic-standard 50 m competition pool with an attached hydrotherapy tank, learn-to-swim pool and gym suite — a configuration that matches three of the facilities listed later in this guide.

Air volume

The 50 m × 25 m competition pool surface (1,250 m2) at AS 1668.2 V_a = 6 L/s/m2 gives 7,500 L/s of pool-deck outdoor air. The hydrotherapy pool at 12 m × 8 m (96 m2) at the same V_a gives 576 L/s. The learn-to-swim pool at 20 m × 10 m (200 m2) gives 1,200 L/s. The splash deck wet zone at 80 m2 gives 480 L/s. Adding occupant ventilation for the 1,500-seat spectator gallery (15,000 L/s at 10 L/s per person) and the 1,000 m2 gym suite (1,000 L/s at 10 L/s/person typical) and the change room exhaust (12 air changes per hour on 600 m2) takes the total outdoor air demand above 35,000 L/s. The supply air, with recirculation, typically lands between 50,000 and 70,000 L/s spread across three to five AHUs.

Temperature and humidity

Competition pool hall air at 28 to 29 degrees C, 50 to 60 percent RH. Hydrotherapy hall at 33 to 34 degrees C, up to 65 percent RH on a separate AHU. Learn-to-swim hall at 30 to 31 degrees C with the same humidity band. Spectator gallery at 22 to 24 degrees C, 45 to 55 percent RH on a third AHU. Change rooms at 24 degrees C with negative pressure to prevent humid air migration toward dry-side amenities. Each setpoint group runs on its own AHU loop — a design move dealt with in detail in the zoning section below.

Acoustic

Pool halls are inherently reverberant — hard floor, water surface, glazing — and acoustic targets are set realistically. SBKJ recommends NC-50 in the competition pool hall, NC-45 in the learn-to-swim hall, NC-40 in change rooms and dry-side amenities, NC-30 in the spectator gallery seating area, NC-25 in meeting and briefing rooms. The duct system contributes to NC via fan-end discharge, in-duct turbulence and diffuser selection — and the designer who pushes for sub-NC-40 in a pool hall is fighting hydrodynamic reality.

Chloramine — the molecule that destroys ductwork

Chloramines are the reaction products between free chlorine in the pool water and nitrogenous compounds (urea, ammonia, amino acids) introduced by bathers. They exist in three forms: monochloramine (NH2Cl), dichloramine (NHCl2) and trichloramine (NCl3). Trichloramine is the one we care about because it is volatile — it leaves the water and accumulates above the pool surface, where it attacks ductwork, structural steel, glazing seals and electrical fittings.

In a council aquatic centre with 200 to 400 bathers per hour at peak, the trichloramine concentration above the water surface routinely runs between 0.3 and 0.5 milligrams per cubic metre — well above the World Health Organization indoor air guideline of 0.5 mg/m3 and the European industrial limit of 0.3 mg/m3 used in some occupational settings. The molecule is corrosive in the gas phase. It oxidises zinc, attacks aluminium oxide passivation layers and pits austenitic stainless steel through chloride-driven crevice corrosion when residual condensation forms inside ductwork.

Surface skim duct — the first line of defence

The single most important duct-side intervention for chloramine control is the surface skim duct. It is a low-level return duct running along the long edges of each pool, with its inlet face 100 to 200 mm above the water surface, capturing trichloramine before it disperses upward into the hall. The capture velocity at the inlet face should be 0.5 to 1.0 m/s — fast enough to skim the boundary layer above the water, slow enough to avoid stirring evaporation. The skim duct routes to a dedicated return-air plenum on the AHU, where it is either exhausted directly (most common in high-bather-load designs) or passed through activated carbon filtration before partial recirculation.

The skim duct itself is the most corrosively exposed section of ductwork in the entire facility. It runs at near-100 percent humidity in service, sees direct splash from the pool surface, and accumulates condensation on every internal seam. The default SBKJ specification is 316L stainless with TIG-welded longitudinal and transverse seams, internal condensation drain points every 6 m, and a 1 in 200 slope to a stainless drain pan. Anything less than 316L will fail within five years.

Return air filtration

Where part of the return air is recirculated — energy-recovery reasons, dehumidification load reduction — the return path needs activated carbon filtration. Carbon beds remove residual trichloramine, dichloramine and the broader chlorinated organic volatile organic compound (VOC) fraction that drifts off the pool surface. Bed depth is typically 50 to 100 mm with face velocity of 0.5 m/s; replacement interval is six to twelve months depending on bather load. The bed itself must be downstream of a particulate pre-filter to extend service life, and the carbon cartridge mounting frame must be 316L stainless because spent carbon weeps chloride-laden moisture into the surrounding ductwork on every change-out cycle.

VOC capture — the chlorinated organics

Beyond trichloramine, the chlorinated organics — chloroform, dichloroacetonitrile, trichloropropanone and the broader trihalomethane family — accumulate in the pool hall air at concentrations well below acute toxicity but well above what regulators target for long-term occupant exposure. They are produced when free chlorine reacts with bather organics in the water and partition into the air at low partial pressure. The same activated carbon filtration that captures residual trichloramine handles the bulk of the chlorinated organic VOC load, although the saturation point on carbon is different molecule-by-molecule. For high-end venues — the Olympic competition halls — the design intent is fresh-air dilution first (the 6 L/s/m2 number) with carbon polish second, not the other way around.

Salt water versus chlorinated pools — the material distinction

Roughly one in five Australian municipal aquatic centres now operates salt-chlorinated pools, where free chlorine is generated on demand by electrolysing dissolved sodium chloride. The bather-facing experience is gentler — the water feels softer, there is less skin and eye irritation — but the air-side problem changes.

A salt water pool produces the same chloramine spectrum as a traditional chlorinated pool because the chlorine chemistry is identical once free chlorine is in solution. What changes is the secondary aerosol. Sodium chloride droplets escape the water surface through wind and bather motion, drift through the hall air and deposit on every horizontal surface, including the inside of ductwork. The chloride ion concentration on duct walls is materially higher in a salt water facility, and chloride-driven pitting corrosion on austenitic stainless steel accelerates correspondingly. The mechanism is well-documented in the petrochemical and offshore corrosion literature: chlorides break down the passive chromium oxide layer on 316L, initiate pits at micro-defect sites, and propagate the pits under crevice conditions (a seam, a flange gasket, a bracket weld).

For salt-chlorinated pools the SBKJ default specification moves from 316L stainless to duplex 2205 (or super-duplex 2507 for tropical climates) above the pool surface. Duplex stainless has roughly twice the chloride pitting resistance of 316L because of the dual-phase ferrite-austenite microstructure and the higher chromium-plus-molybdenum content. The trade-off is fabrication: duplex requires tighter heat input control during TIG welding to avoid phase imbalance, and shop floor staff need targeted training. SBKJ ductwork machines handle duplex coil identically to 316L from a forming perspective, but the welding cell needs argon shielding gas with the correct nitrogen addition.

Material selection — the council facility specification

For a public aquatic centre or competition venue, ductwork material selection should be zoned by chloramine exposure rather than averaged across the facility. The SBKJ specification ladder is:

• Within 3 m vertical of any pool surface — 316L stainless steel (chlorinated pools) or duplex 2205 (salt water pools). TIG-welded longitudinal seams. Continuous-welded transverse joints. No lockformed seams.
• Pool hall ceiling and roof void — 316L stainless or, where condensation is controlled to below 70 percent RH and never reaches the dew point on duct surfaces, marine-grade aluminium 5052-H32 or 5083. Galvanized is acceptable only where independent condensation modelling demonstrates zero credible chloramine deposition (rare in council facilities).
• Plant deck and chemical store exhaust — fibreglass-reinforced plastic (FRP) or PVC for chlorine and acid exhausts; 316L for combined return paths.
• Change rooms and amenities — galvanized G90 with sealant on transverse seams; aluminium where shower-room humidity is unmanaged.
• Dry-side fitness suite and spectator gallery — standard galvanized G90 to AS/NZS 4254.
• Outdoor make-up air ducts — galvanized G90 with external weatherproof coating, or aluminium in coastal facilities (Bondi, Cottesloe, Glenelg).

The cost premium for 316L over galvanized is typically 4 to 5 times on raw material and roughly 2 times on installed metre, depending on seam type. For a council aquatic centre with 8 to 12 km of ductwork the absolute capital uplift is between 600,000 and 1.2 million AUD — material against the avoided cost of a 5-to-7-year replacement cycle on galvanized, which routinely runs 2 to 3 million AUD per cycle including business interruption, the 316L decision is straightforwardly cheaper over the 30-year facility lifecycle.

The seam — where ductwork actually fails

A 316L duct with a leaky seam fails in chloramine service almost as fast as a galvanized duct, because the failure mode is condensation pooling at the seam line and chloride accumulation in the pool. The seam strategy is therefore as load-bearing as the material grade itself.

Longitudinal seam

The longitudinal seam runs the length of every duct section. For aquatic 316L the options are:

• TIG-welded seam (gas tungsten arc welding) — the default for SBKJ aquatic ductwork. Argon-shielded, autogenous (no filler) or with 316L filler. Continuous weld with full penetration. Inspected by liquid penetrant test (PT) every 6 m. This is the seam class that survives 25 years in service.
• Plasma-welded seam — acceptable substitute. Faster than TIG but requires tighter edge preparation.
• Resistance-seam welded — acceptable for 304 stainless in dry-side zones; not recommended for 316L in chloramine zones because the heat-affected zone is wider.
• Pittsburgh lockformed with sealant — not acceptable above pool surfaces. The mechanical lock leaves a capillary path that wicks condensation; the sealant degrades in chloramine within 18 months.

Transverse joint

Where two duct sections meet, the transverse joint is either:

• Welded flange — 316L flange welded to each section, bolted joint with EPDM gasket rated for chlorine service. Default for aquatic.
• TDF/TDC integral flange — formed from the parent material. Acceptable in galvanized dry-side zones; not for 316L pool zones (the formed corner work-hardens and cracks under chloramine).
• Slip joint with stainless screws and sealant — service entry only.

Why SBKJ ships TIG welders with the SBAL-V

The SBAL-V Bending Machine is the SBKJ stainless duct production cell that pairs the forming line with an integrated TIG seam welder, designed specifically for aquatic and food-grade applications. The welder runs continuous longitudinal welds on coil widths up to 1,500 mm and thickness range 0.6 to 1.5 mm, with argon shielding, automatic arc length control and integrated liquid penetrant testing on a 6 m gauge. Where the buyer specifies argon backing for root-side weld protection, the line accepts an inline backing fixture that delivers argon to the weld pool underside — necessary for chloramine-exposed ductwork where pit initiation starts at the weld root if the underside has been air-exposed during welding.

AHU zoning — five AHU groups in a council aquatic centre

The single most common design mistake in aquatic centres is collapsing the AHU count to save capital cost. The correct AHU count for a competition-grade council facility is five — and trying to run that on three or four is the reason most renovation tenders include thermal-comfort complaints in the scope.

AHU-1 — Competition pool hall

Serves the 50 m or 25 m competition tank plus the surrounding deck. Setpoint 28 to 29 degrees C dry-bulb, 50 to 60 percent RH. Includes the surface skim duct return, the deck-level supply diffusers, the high-level exhaust headers and the dehumidification coil. AHU sized on the dehumidification load (evaporation rate × wet-bulb depression) rather than on sensible cooling, which is typically a third the size of the latent load.

AHU-2 — Learn-to-swim and recreational pool hall

Where the facility includes a separate learn-to-swim or recreational tank in its own hall, this gets its own AHU. Setpoint 30 to 31 degrees C dry-bulb. Operating hours vary independently from the competition hall (school program in the morning, public in the afternoon) and the energy penalty of running both halls on a single AHU is the equivalent of 10 to 15 percent of total facility consumption.

AHU-3 — Hydrotherapy

Hydrotherapy water is 32 to 35 degrees C — substantially warmer than competition or recreational pools — and the air must be 33 to 36 degrees C with up to 65 percent RH to maintain bather thermal comfort. Hydrotherapy serves a clinical population (post-surgical rehabilitation, paediatric physiotherapy, geriatric exercise) and the air quality requirements include lower NC targets (NC-35 typical). A separate AHU is non-negotiable.

AHU-4 — Spectator gallery and reception

The spectator gallery seats a dry-clothed population at a setpoint of 22 to 24 degrees C, 45 to 55 percent RH. Sharing an AHU with the pool hall pushes the spectator zone into uncomfortable warmth and humidity. Where the gallery seats 1,000 or more (typical for Olympic competition venues), the AHU includes its own dehumidification coil and an independent fan section with VSD control for events with variable attendance.

AHU-5 — Change rooms, dry-side amenities and fitness suite

Change rooms are exhausted at 10 to 12 air changes per hour with negative pressure differential to the pool hall (5 to 10 Pa) to prevent humid air migration. The fitness suite, group exercise studios and reception areas combine onto a single dry-side AHU with conventional comfort cooling. The plant deck and chemical stores run on a separate dedicated exhaust system independent of any AHU return path.

Wet plant deck and chemical handling

The wet plant deck — the room or rooms housing pool circulation pumps, sand or glass-media filters, chlorine dosing equipment, acid dosing for pH control, balance tanks, and (in many facilities) the heat pump or boiler plant for pool heating — is the most chemically aggressive space in the entire facility. AS 4575 chemical storage requirements and AS/NZS 3666 microbial management requirements both apply, and the ductwork specification is driven by direct chemical exposure rather than chloramine alone.

• Chlorine store — dedicated negative-pressure exhaust at 12 to 15 air changes per hour. FRP or PVC ductwork. No return path. Redundant fans (N+1 minimum). Chlorine gas detector interlock to fan start. Make-up air via a louvre on the opposite wall.
• Acid store (typically hydrochloric or sulphuric for pH control) — same regime as chlorine store, separate exhaust. FRP ductwork. Make-up air separate from chlorine store to prevent any chance of cross-mixing.
• Filter hall — high humidity, splash exposure. 316L stainless ductwork for general ventilation. 12 air changes per hour.
• Heater room — gas-fired heaters need combustion air per AS 4575; the combustion air intake should never share a wall with the chlorine store exhaust.

Spectator gallery — why it gets its own AHU

The spectator gallery is the single most common source of post-handover comfort complaints in aquatic centres. The complaint is always the same: at full event capacity, the gallery is too warm, the air feels heavy, and condensation collects on the lower edge of the gallery glazing where it overlooks the pool hall. The root cause is almost always shared AHU service between the gallery and the pool hall.

A spectator gallery has a different humidity tolerance from a pool hall. The seated, dry-clothed occupant wants 45 to 55 percent RH. The wet bather population in the hall below wants 50 to 60 percent RH. The two setpoint bands overlap but are not identical, and the energy penalty of running both zones at the higher humidity is significant — typically 8 to 12 percent of total HVAC energy on the facility. More importantly, the dehumidification capacity required for the pool hall (driven by evaporation load) is many times the capacity required for the gallery (driven by occupant moisture), and sizing one AHU for both produces a unit that under-dehumidifies one space or over-dehumidifies the other.

The correct approach is a separate AHU for the spectator gallery, with its own outdoor air intake, its own dehumidification capacity sized on occupant load, and its own VSD-driven supply fan that ramps down between events. The duct routing should physically separate gallery supply from pool hall supply — no shared trunks — and the gallery return should not pass through the pool hall on its way to the AHU.

Hydrotherapy — the warm pool zone

Hydrotherapy pools are warmer (32 to 35 degrees Celsius) and shallower (typically 1.2 to 1.4 m) than recreational or competition pools. They serve a clinical population — post-surgical, paediatric, geriatric — and the operating program is usually a mix of guided physiotherapy sessions and supervised exercise classes. The HVAC requirements differ from the rest of the facility in four ways.

First, the air temperature must be high enough to prevent bather chilling on exit. The standard recommendation is 1 degree Celsius below the water temperature for hydrotherapy (the inverse of the rule for competition pools), so 33 to 34 degrees C air for a 34 degree C pool. Bathers who feel cold after exiting hydrotherapy stop attending, and the facility loses its core clinical user base.

Second, the relative humidity tolerance is higher. Up to 65 percent RH is acceptable in hydrotherapy because the bather population is wet-clothed for most of the session and the structural condensation risk is lower (smaller hall, less glazing). Pushing RH down to 50 percent in hydrotherapy is an energy penalty without a clinical benefit.

Third, the air quality requirements are more stringent. Hydrotherapy serves immunocompromised users (post-cardiac surgery, post-orthopaedic) and the chloramine concentration target is below 0.2 mg/m3 — below the council-facility average of 0.3 to 0.5 mg/m3. That drives the outdoor air rate higher (8 to 10 L/s/m2 in some specifications, above the AS 1668.2 minimum) and the carbon filtration polish heavier.

Fourth, the acoustic target is more aggressive. NC-35 in a hydrotherapy hall versus NC-50 in a competition hall, because the clinical environment requires verbal instruction at conversational level.

Splash deck, kids zone and integrated leisure water

Many modern council aquatic centres include a splash deck or interactive water play zone — shallow water (50 to 200 mm), interactive jets, tipping buckets, slides and themed water features. The chloramine load on a splash deck is disproportionately high because the water surface area per bather is high, agitation is constant, and the bather population skews young (high urea contribution). The HVAC zoning treats the splash deck as a separate sub-zone within the recreational hall AHU, with its own dedicated skim duct array running around the perimeter and a higher local outdoor air rate (8 L/s/m2 typical).

Where the splash deck is enclosed in a separate themed enclosure (jungle, lagoon), the AHU loop is split out completely. Where it is integrated into the main learn-to-swim hall, the skim duct is dimensioned for the higher load and the supply diffuser layout pushes air down rather than along the deck.

Gym suite and group exercise integration

Most council aquatic centres now bundle a gym suite, group exercise studios, café and crèche into the same building envelope. The HVAC integration question is whether to put the dry-side fitness program on the same AHU as the wet-side amenities, and the answer is universally no.

A gym suite generates substantial latent and sensible load (a 50-person spin class delivers roughly 30 kW of sensible heat and 1 to 1.5 L/h of moisture per occupant). The setpoint is 18 to 20 degrees C with 40 to 50 percent RH. Sharing an AHU with the wet-side amenities forces a compromise that satisfies neither population, and the air-quality cross-contamination risk (chloramine drift from the pool hall into the gym, where it triggers exercise-induced asthma) is documented in the occupational health literature.

The correct configuration is a dedicated dry-side AHU for the fitness suite, with its own outdoor air intake routed away from any pool hall exhaust discharge and a clear pressure differential to keep gym air positive against the pool hall. The corridor connecting the wet and dry sides should be a transfer zone with its own air balance, not a free communication path.

NABERS Aquatic Centres and Climate Active certification

The Australian energy disclosure regime is moving toward aquatic centres. NABERS (National Australian Built Environment Rating System) has the Aquatic Centres sector under active development, with pilot ratings already conducted at several large facilities. The likely metric will combine total energy intensity (MJ per visitor or per pool surface area), water consumption and waste handling, benchmarked against a notional reference building. Mechanical consultants designing aquatic facilities in 2026 and beyond should assume the NABERS Aquatic Centres rating will be a tender requirement within the contract life of the building.

Climate Active is the federal voluntary carbon neutrality certification, and a growing share of councils — Sydney City, Yarra City, City of Melbourne, City of Sydney — have committed to Climate Active certification across their facility portfolios. For aquatic centres the carbon path includes electrified pool heating (heat pump or solar-thermal-with-heat-pump), high-efficiency dehumidification, heat recovery on every AHU and PV generation matched to the daytime pool program. The ductwork specification is upstream of all of this — the AHU efficiency, the leakage class, the heat recovery effectiveness and the fan power index all depend on the duct system airtightness — and a Climate Active aquatic centre cannot afford SMACNA leakage Class 6 (the default for galvanized lockformed) when the specification target is leakage Class 3 sealed-seam 316L.

Brisbane 2032 — the venue pipeline

The Brisbane 2032 Olympic and Paralympic Games is the largest aquatic capital pipeline in Australian history. The Brisbane 2032 Delivery Authority confirmed the aquatic program in 2024 and the detailed venue list is being progressively contracted through 2026 to 2030. From an HVAC ductwork perspective the relevant venues are:

• Brisbane Aquatic Centre (planned) — a new Olympic-standard aquatic venue, replacing the Centenary Pool footprint at Spring Hill. FINA-standard 50 m × 25 m × 3 m main competition pool, 25 m secondary, diving tank, hydrotherapy, training pool, spectator gallery. Highest specification on the pipeline.
• Brisbane Centenary Pool redevelopment — the 1982 Commonwealth Games legacy facility at Spring Hill, being substantially redeveloped into the new competition venue.
• QSAC (Queensland Sport and Athletics Centre) upgrades — the Nathan campus is being expanded as a training and warm-up venue for the Games.
• Gold Coast Aquatic Centre (Southport) — the 2018 Commonwealth Games legacy venue is being upgraded for Games use, including AHU replacements and 316L ductwork retrofits.
• Regional training pools — Sunshine Coast and Ipswich are planned regional training facilities, with full Brisbane 2032 specification but downsized spectator capacity.

Across the pipeline the common design themes are FINA-compliant pool dimensions, NABERS Aquatic Centres target ratings of 5 stars or better, Climate Active certification pathway, electrified pool heating with heat-pump primary and solar-thermal supplement, and 316L stainless ductwork above all pool surfaces. The procurement model is mostly Design and Construct on managing contractor with the mechanical scope let as a subcontract, which puts the ductwork specification at the level of the trade contractor — and that is where SBKJ machinery sees most of its Brisbane 2032 demand: trade contractors needing the production capacity to deliver 6 to 12 km of 316L ductwork on a 12-month program.

The legacy Olympic and Commonwealth Games venues

Sitting alongside the Brisbane 2032 pipeline is the maintenance and refurbishment program at the existing Australian Olympic and Commonwealth Games aquatic venues. Most of these were commissioned for the 2000 Sydney Olympics, the 1982 Brisbane Commonwealth Games, the 2006 Melbourne Commonwealth Games and the 2018 Gold Coast Commonwealth Games — all are now 8 to 44 years old and well into the second or third cycle of HVAC ductwork replacement.

Sydney Olympic Park Aquatic Centre

SOPAC at the Sydney Olympic Park site was the venue for the 2000 Olympics swimming and diving program and remains one of Australia's largest aquatic facilities. The original ductwork was galvanized — entirely standard practice for 1999 commissioning — and has been progressively replaced since 2014 with 316L stainless. Operated by Sydney Olympic Park Authority (SOPA), the venue runs a competition pool, leisure pool, diving tank, hydrotherapy and gym suite with full spectator capacity.

Melbourne Sports and Aquatic Centre (MSAC)

MSAC at Albert Park is the State Sport Centres Trust facility that served the 2006 Commonwealth Games and remains Victoria's competition aquatic centre. The HVAC has been progressively renovated since 2012 with the main competition hall AHU upgraded in 2018 and 316L ductwork retrofits planned across the next capital cycle.

Andrew (Boy) Charlton Pool and Cook + Phillip Park Pool

The City of Sydney operates two flagship inner-city pools: Boy Charlton at the Domain (outdoor saltwater, with HVAC requirements limited to change rooms and amenities) and Cook + Phillip Park at College Street (50 m indoor competition pool, full HVAC envelope). Both are City of Sydney-operated and follow City of Sydney sustainability commitments (Climate Active pathway).

Cottesloe Beach Pool

The Town of Cottesloe operates Cottesloe Beach Pool, a coastal saltwater facility where the corrosion environment is doubly aggressive — chloramine plus marine salt aerosol. Ductwork specification is duplex 2205 for any internal duct above the water surface, super-duplex 2507 for outdoor exposed sections.

Beatty Park Leisure Centre

The City of Vincent in Perth operates Beatty Park, the 1962 Commonwealth Games legacy venue with 50 m competition pool, learn-to-swim, hydrotherapy and gym suite. The facility was substantially refurbished in the 2010s with 316L stainless ductwork installed in the chloramine zones.

Adelaide Aquatic Centre

The Adelaide Aquatic Centre at North Adelaide is the City of Adelaide flagship facility. The original 1969 building has been progressively expanded and was confirmed in 2023 for a major rebuild, with substantial completion targeted for 2026 to 2028 depending on site staging. The new facility specification calls for 316L stainless ductwork throughout all chloramine-exposed zones, NABERS Aquatic Centres pilot rating and Climate Active certification pathway.

Glenelg Foreshore Aquatic Centre

The City of Holdfast Bay operates the Glenelg Foreshore Aquatic Centre, a coastal facility with the same marine-plus-chloramine corrosion environment as Cottesloe. Material specification is duplex 2205 for chloramine zones, marine-grade aluminium for outdoor make-up air.

HBF Stadium Mt Claremont

HBF Stadium at Mount Claremont in Perth is the VenuesWest facility hosting Swimming WA competition and training. The 50 m competition pool serves national-level training and is operated to FINA-equivalent specification. The ductwork has been substantially upgraded over the past decade with 316L retrofits in the pool hall and AHU replacements scheduled across the 2026 to 2030 capital pipeline.

Goulburn Aquatic and Leisure Centre

Goulburn Mulwaree Council operates the Goulburn Aquatic and Leisure Centre, a regional NSW facility serving Goulburn and the southern tablelands. It is representative of the regional council aquatic tier — substantial bather load, year-round operation, full HVAC envelope, but at scale below the metropolitan flagships.

Aquanation Ringwood and the Aqualink chain

Maroondah City Council operates Aquanation in Ringwood, opened in 2014 with full 316L stainless ductwork from commissioning — one of the earliest Australian examples of stainless-from-day-one specification at council scale. The Aqualink chain (Box Hill and Nunawading) operated by Whitehorse City Council follows similar specifications across its competition and recreational pool programs.

Australian Swim Schools Association — the learn-to-swim integration

Council aquatic centres are the largest single customer base for the Australian Swim Schools Association (ASSA) — the peak body for learn-to-swim providers including Carlile Swimming, JUMP! Swim Schools, Paul Sadler Swimland, Australian Crawl and dozens of regional brands. ASSA-aligned programs typically lease pool time from council facilities, which means the AHU sizing and zoning must accommodate the learn-to-swim program in addition to the recreational and competition program.

The learn-to-swim program runs short, intense bursts of high bather load — 20 children plus instructors in a small water volume for 30 minutes, then another cohort. The chloramine generation rate during a learn-to-swim block is several times the rate during open lap swimming, and the AHU outdoor air rate should be sized on the peak learn-to-swim load rather than the average daily load. Where the learn-to-swim pool has its own hall (Aquanation, several of the SOPA venues, the new Adelaide Aquatic Centre), the AHU zoning naturally accommodates this. Where the learn-to-swim program shares a hall with recreational swimming, the AHU control must include a programmed schedule that ramps outdoor air during learn-to-swim blocks.

Funding and the grants landscape

Council aquatic centre HVAC retrofits are increasingly funded through combinations of council capital budget, state Office for Sport grants, federal Australian Sports Commission grants and the Australian Sports Foundation tax-deductible fundraising platform. The funding landscape directly influences the procurement model:

• State Office for Sport grants (NSW Office of Sport, Sport Victoria, Sport and Recreation QLD, DLGSC WA, Office for Recreation Sport and Racing SA) — typically co-funded with council capital, often time-limited (24-month delivery from grant agreement), driving compressed mechanical delivery timelines.
• Australian Sports Foundation — fundraising vehicle increasingly used by regional councils to top up capital for facility upgrades.
• Federal Aquatic Centres program (where active) — periodic federal funding rounds for community pool upgrades, particularly in regional and remote areas.
• Brisbane 2032 Delivery Authority capital — the largest aquatic capital pipeline currently in Australia, with prequalified contractor pools and FIDIC-style head contracts.

SBKJ machine configuration for public aquatic centres

For trade contractors and ductwork fabricators bidding into the Australian aquatic vertical, the SBKJ machine configuration that meets the technical envelope above is consistent across project sizes. The minimum production cell is:

• SBAL-V Bending Machine — stainless coil capacity to 1,500 mm width, 0.6 to 1.5 mm thickness, full hydraulic clamp and bend cycle, Mitsubishi or Siemens PLC. Configured for 316L coil out of the box, accepts duplex 2205 with shielding gas changeover. See the SBAL-V on the SBKJ machine catalogue.
• SBKJ TIG seam welder (inline) — argon-shielded longitudinal seam welder integrated with the bending line. Continuous weld on 0.6 to 1.5 mm 316L. Argon backing fixture optional. Automatic arc length control. Liquid penetrant test station at 6 m gauge.
• Stitchwelder — secondary cell for spot and tack welding on flange-to-section attachment.
• Gorelocker — for the dry-side galvanized fraction of the same project, where lockformed seams are acceptable.

For competition-grade Olympic venues — Brisbane 2032 pipeline — the typical configuration adds an orbital welding head for 90-degree elbow seams and a coil edge prep station for tight-radius bends. Total cell footprint runs 60 to 80 square metres of shop floor.

Every line ships sealed-seam Class A ductwork compliant with AS/NZS 4254.1 and SMACNA leakage Class 3 — the specification level required for the chloramine return paths in any council aquatic centre and every Brisbane 2032 venue.

Procurement timeline — council aquatic projects

A council aquatic centre HVAC refurbishment typically runs to a 24-month timeline from feasibility study to commissioning. The ductwork procurement sits at month 8 to 14 in that timeline:

• Months 0 to 4 — feasibility study, condition assessment, grant application, council capital approval.
• Months 4 to 8 — schematic design, mechanical consultant brief, AHU sizing, ductwork specification.
• Months 8 to 12 — tender documentation, RFP issue, contractor selection.
• Months 12 to 14 — ductwork machine procurement (where the trade contractor lacks 316L capacity), ductwork shop drawings, factory acceptance test.
• Months 14 to 22 — facility shutdown, ductwork removal, AHU replacement, ductwork installation, electrical and controls integration.
• Months 22 to 24 — commissioning, balancing, chloramine measurement, acoustic verification, NABERS pilot rating (where applicable), handover.

For Brisbane 2032 venues the timeline is longer (typically 36 to 48 months) and the procurement model is managing contractor with prequalified subcontractors, but the ductwork machine procurement step sits at roughly the same fraction of the timeline.

Common procurement mistakes — and the fixes

Across the council and Olympic-pipeline aquatic centres we have supplied ductwork machinery to over the past decade, five procurement mistakes recur. Each one is preventable at specification stage.

• Specifying galvanized in chloramine zones to save capital. The math never works over a 30-year lifecycle. The fix: 316L mandatory within 3 m vertical of any pool surface.
• Collapsing the AHU count from five to three or four. Produces thermal comfort complaints in the spectator gallery, energy waste in the change rooms and chloramine cross-contamination in the gym. The fix: five AHU groups minimum for any council competition-grade facility.
• Treating salt water pools as equivalent to chlorinated pools for material selection. Chloride pitting accelerates 316L failure. The fix: duplex 2205 above the pool surface for any salt-chlorinated facility.
• Sealing seams with mastic instead of welding. Mastic degrades in chloramine within 18 months. The fix: TIG-welded longitudinal seams and welded flange transverse joints throughout all chloramine zones.
• Skipping the Factory Acceptance Test on the ductwork batch. Site discovery of leakage class failures or seam radiography failures sets the program back 8 to 12 weeks. The fix: full FAT including leakage testing, seam PT and dimensional check on a representative production batch before delivery.

Operations and maintenance — the 25-year regime

A well-engineered 316L ductwork system in a council aquatic centre has a 25-year design life if the operations and maintenance regime is properly handed over and followed. The five elements are:

• Carbon filter replacement on the chloramine return path every 6 to 12 months depending on bather load.
• Particulate filter replacement on the AHU pre-filter every 3 months.
• Condensation drain inspection at every horizontal duct low point every 6 months; flush and clean every 12 months.
• Internal duct surface inspection via service access at 5-year intervals; visual check for pitting, weld degradation and biofilm.
• AS/NZS 3666 cooling tower management per the standard's specified schedule — monthly inspection, six-monthly chemical clean, Legionella testing at prescribed intervals.

Hand-over documentation should include the original mill certificates for the 316L coil, the TIG weld procedure specification and welder qualification records, the FAT report, the air balance report, the chloramine measurement report at commissioning, and a digital model of the duct system for future maintenance planning.

How SBKJ engineers approach an aquatic project

When a trade contractor or mechanical consultant approaches SBKJ with an aquatic project brief, our engineering team walks through five steps before quoting machinery:

1. Pool program review — what tanks, what surface areas, what water temperatures, what bather load profile, what spectator capacity.
2. Standards stack confirmation — ASHRAE 62.1 baseline, ASHRAE Chapter 6 reference, AS 1668.2 V_a, AS/NZS 1838 chemistry assumptions, AS/NZS 3666 cooling tower exposure, AS/NZS 4254 ductwork class.
3. Material selection ladder — 316L mandate zone, duplex 2205 if salt-chlorinated, dry-side galvanized fraction, chemical store FRP.
4. AHU zoning confirmation — five-AHU baseline, deviation justified explicitly where the project differs.
5. Production cell sizing — total linear metres of 316L by gauge and width, total linear metres of galvanized, TIG welder hours, single-shift versus double-shift output requirement, FAT batch definition.

The output is a machine configuration recommendation, a single-page landed-cost worksheet against the buyer's chosen Incoterm, an FAT protocol and a commissioning supervision quotation. SBKJ engineers reply within 12 hours to every aquatic project enquiry — not a salesperson, an engineer who has commissioned aquatic ductwork lines on three continents.

Get an SBKJ aquatic ductwork specification →

FAQ

Why does galvanized ductwork fail in aquatic centres within 3-7 years?

Trichloramine released from the pool water attacks the zinc layer on galvanized steel through pitting corrosion. In a high-bather-load council aquatic centre the chloramine concentration above the water surface routinely exceeds 0.3 mg/m3 — enough to perforate G90 galvanized within 3 to 7 years. The only durable specification for ductwork above the pool surface is 316L stainless with TIG-welded seams.

What air change rate does a 50m Olympic competition pool hall need?

AS 1668.2 requires 6 L/s per square metre of pool surface as the minimum outdoor air rate. For a 50 m × 25 m pool (1,250 m2), that is 7,500 L/s — typically supplemented with recirculated air to reach 4 to 6 air changes per hour at the pool deck level, with the spectator gallery on a separate AHU.

What temperature and humidity should a competition pool hall maintain?

Dry-bulb air temperature 1 to 2 degrees Celsius above water temperature and relative humidity controlled between 50 and 60 percent — drawn from ASHRAE Chapter 6 and the FINA facility guidance. A 27 degree C competition pool means 28 to 29 degree C air. Hydrotherapy pools run higher temperatures and tolerate up to 65 percent RH on a separate AHU loop.

Does Brisbane 2032 require new aquatic ductwork specifications?

The Brisbane 2032 venue pipeline (Brisbane Aquatic Centre, Centenary Pool redevelopment, QSAC, Gold Coast Aquatic Centre and regional training pools) drives material selection toward 316L stainless above pool surfaces, NABERS Aquatic Centres target ratings and Climate Active certification pathways. The detailed specifications are confirmed venue-by-venue under the Brisbane 2032 Delivery Authority.

What is the difference in ductwork between chlorinated and salt water pools?

Salt-chlorinated pools release sodium chloride aerosols alongside chloramines, raising chloride ion deposition on ductwork and accelerating pitting corrosion on austenitic 316L stainless. The SBKJ default for salt water pools is duplex 2205 (or super-duplex 2507 in tropical climates) above the pool surface, with the same TIG-welded seam regime.

What SBKJ machine configuration suits a council aquatic centre?

An SBAL-V Bending Machine configured for 316L stainless coil up to 1.5 mm thickness, paired with an inline TIG seam welder rated for continuous longitudinal welds. The combined cell produces sealed-seam Class A ductwork compliant with AS/NZS 4254.1 and SMACNA leakage Class 3, suitable for the chloramine return paths in any council aquatic centre and Olympic competition venue.