Auto Dealership and Service Centre HVAC Duct Guide — Showroom, Service Bay, Panel Beating, Parts

Why a dealership is the hardest HVAC job in retail

The modern Australian automotive dealership is the most schizophrenic building type in commercial construction. Within a single property line — sometimes under a single roof — the mechanical contractor is asked to design hospitality-grade HVAC for a marble-floored Mercedes-Benz showroom, industrial vehicle exhaust extraction for a 12-bay service workshop, NFPA 33 paint booth ventilation for a smash repair operation that may share the site, climate-controlled storage for high-value OEM parts and aftermarket batteries, customer lounge comfort that rivals a barista cafe, parts office workstations, and now in 2025 and beyond, dedicated mechanical extract for direct-current EV fast-charging cabinets that dump 50 to 350 kilowatts of waste heat into the building.

No other commercial building type spans this range. A supermarket is 90% ambient retail with a small back-of-house. A hotel is 100% hospitality. A factory is 100% industrial. A car dealership is all of them simultaneously, separated only by a glass internal wall and a fire door. The HVAC ductwork has to span that range, switching from AS 4254 Class 2 galvanised to stainless steel to flexible at the paint shop boundary, from NC-40 hospitality acoustic targets to industrial source-capture extraction within 30 metres, from continuous occupancy showroom airflow to demand-controlled parts warehouse trickle ventilation.

This guide is the engineering brief our mechanical contractor customers use when bidding on Australian dealership work — whether the end client is a single-site family dealer in regional Victoria, a luxury franchise on Toorak Road, or one of the listed dealer groups operating 200-plus sites across the Eastern Seaboard. It covers the codes that apply, the design conditions each space type requires, the duct fabrication implications, and the SBKJ machinery configuration that lets a contractor build the galvanised majority and the stainless paint shop boundary on the same shop floor.

The Australian dealership landscape

To design ductwork that survives a dealership tender process, the engineer needs to understand who is buying. The Australian automotive retail market is consolidated and listed — a fact that drives standardisation of HVAC briefs across the country. The largest operators set the brand specifications and the smaller operators inherit them.

Eagers Automotive (ASX:APE) is the largest, operating roughly 250 sites across every state and territory, representing more than 30 brands from entry-level Hyundai and Kia through to Ferrari and McLaren. Eagers absorbed AP Eagers in the 2019 merger and now operates the consolidated entity from its Brisbane head office. Mechanical contractors bidding on Eagers work see a national HVAC specification that is updated annually and references AS 1668.2, AS 4254, and brand-specific corporate identity overlays.

Peter Warren Automotive (ASX:PWR) is the second listed dealer group, headquartered at Warwick Farm in Sydney's south-west. Peter Warren's footprint is concentrated in New South Wales with luxury and prestige franchises including BMW, MINI, Audi, Volkswagen, Volvo, Land Rover and Jaguar. The Peter Warren brief leans more heavily on luxury showroom acoustic and lighting standards because of the brand mix.

Autosports Group is the luxury-only specialist, operating Mercedes-Benz, Audi, Porsche, Lamborghini, Bentley, Aston Martin, Maserati, McLaren and Volvo retail across Sydney and Melbourne flagship locations. Autosports work routinely specifies NC-35 showroom acoustic targets and demands hospitality-grade air diffusion patterns and supply velocities below 0.2 m/s at customer head height — closer to a five-star hotel than a retail showroom.

Sime Darby Motors Australia operates BMW, MINI, Jaguar, Land Rover, McLaren, Volvo and Trucks dealerships under the parent Sime Darby Group, headquartered in Melbourne. Sime Darby's mechanical specification mirrors BMW Group Corporate Identity standards for showroom acoustic and visual comfort.

Lei Shing Hong (LSH Auto Australia) operates the largest Mercedes-Benz dealerships in Australia, including the flagship LSH Auto retail centre in Melbourne. LSH briefs reference Mercedes-Benz Corporate Identity, which mandates specific brand showroom temperatures, humidity, lighting colour temperatures and supply diffuser geometries. The LSH Doncaster and Berwick sites are reference projects for what a Stage III Mercedes-Benz Retail showroom expects from its mechanical engineer.

Sutton Group and Suttons Motors are the long-established New South Wales family dealers, operating across the Sutton's City Holden, Suttons City, and multi-franchise outlets through Western Sydney and the Central Coast. The Sutton's brief is pragmatic — they want a competent commercial HVAC system that meets brand minima without over-specifying.

On the smash repair side, the Australian network has consolidated into three large groups. Schmick Smash Repairs operates 30-plus sites nationally, predominantly servicing the panel and paint side of insurance referral work. Capital Smart Repairs (linked to PartsTrader) runs a tighter, modular smash repair footprint optimised for small-area damage and rapid turnaround. Suncorp and IAG insurance-affiliated networks push insurance work to preferred panel and paint shops that meet specified turnaround and quality KPIs, indirectly shaping ductwork specifications because the insurer's quality team audits paint booth performance. The independent SCA (Star Combined Auto) network of family-owned smash repairers shares technical infrastructure including some shared HVAC specifications.

On the EV side, the picture is changing fast. Tesla Service Centre Australia operates around 20 service locations from Brisbane to Perth with a service centre brief that is more like an industrial workshop than a luxury franchise — no showroom in the traditional sense, but heavy emphasis on high-voltage workshop safety and battery thermal runaway response ventilation. Polestar uses Volvo dealer-aligned service infrastructure with EV-specific upgrades. Genesis (Hyundai's luxury sub-brand) takes a hybrid approach: dedicated Genesis Studios in Sydney, Melbourne and Brisbane with hospitality-led showroom HVAC, plus service performed at upgraded Hyundai dealer service centres.

Operating hours and HVAC scheduling

A defining characteristic of automotive retail in Australia is that it is not 24/7. Showrooms typically operate 09:00 to 18:00 weekdays with extended Saturday hours, closed Sunday. Service workshops typically operate 07:30 to 17:30 weekdays, Saturday morning. Panel and paint shops sometimes run a second shift but rarely a third. This contrasts sharply with the EV manufacturing plants and food processing facilities that other SBKJ industry guides cover, where 24/7 operation drives continuous mechanical ventilation design.

For the duct system designer, business-hours operation means three things. First, demand-controlled ventilation and CO₂-based fresh air modulation are highly cost-effective because the building empties at night and ventilation can be set back to minimum infiltration replacement rates. Second, after-hours setback strategies must protect display vehicle batteries from cold soak — recent battery chemistry guidance from premium electric and plug-in hybrid manufacturers recommends keeping showroom floor temperatures above 5°C overnight to avoid lithium-ion plating risk. Third, the building's diversity factor between peak occupancy (Saturday morning showroom) and shoulder periods (Tuesday afternoon) is high enough to justify variable-air-volume systems with demand-controlled outside air.

The implication for ductwork sizing is that the system is designed for peak Saturday occupancy but operates most of its hours below 50% of design airflow. Duct fabrication has to accommodate variable air volume terminal boxes, return air bypass paths and shut-off zone dampers, which means more accessories per linear metre of duct than a simpler constant-volume office HVAC system.

The showroom: hospitality-grade HVAC in a retail box

Walk into a Mercedes-Benz Stage III dealership in Melbourne, an Audi Terminal showroom in Sydney, or a Lexus showroom under the current Lexus brand standards, and the room reads more like a luxury hotel lobby than a car retail floor. Polished concrete, walnut joinery, indirect lighting, leather seating around a brand-themed espresso bar, and floor-to-ceiling glazing that performs more like a curtain wall on a five-star tower than a shopfront. The HVAC ductwork has to match the ambition.

Showroom design conditions

Premium franchise corporate identity standards converge on the following design conditions for the showroom, give or take a degree:

• Dry bulb temperature: 22 to 24°C in cooling, 21 to 22°C in heating. Set point typically 23°C year-round with a 1°C dead-band.
• Relative humidity: 45 to 55% target, 40 to 60% acceptable band. Critical for veneer joinery and acoustic comfort; matters less for the vehicles themselves than for the building fabric and customer perception.
• Acoustic background level: NC-40 mass-market, NC-35 to NC-37 luxury brand standards. Audi Terminal and Mercedes-Benz Stage III often specify NC-35.
• Supply air velocity at occupant head height: below 0.25 m/s — no perceivable draft on a customer sitting on a brand-themed lounge chair examining a tablet.
• Outside air per AS 1668.2 Table A1: 7.5 L/s per person plus 0.5 L/s/m² for floor area. For a 1,000 m² showroom expecting peak 50 customers and staff, this gives 875 L/s minimum outside air.
• CO₂ control set point: 800 ppm maximum, demand-controlled outside air ramp above 600 ppm.
• Lighting heat load: 25 to 35 W/m² for premium showroom lighting (track-mounted feature lighting, indirect cove lighting, dynamic display lighting), which adds 25 to 35 kW of cooling load per 1,000 m² of showroom.
• Glazing solar load: dominant in west and north-facing showrooms with floor-to-ceiling glass. Often the single largest cooling load element, 80 to 150 W/m² of glazing area in summer.

Showroom ductwork specification

The showroom ductwork is bread-and-butter commercial HVAC: AS 4254 Class 2 galvanised steel, rectangular for the main trunks and round spiral for smaller branches. The mechanical contractor fabricates this on the SBAL-III auto duct line at 60 to 80 linear metres per hour single-shift. Specific specifications:

• Material: Pre-galvanised steel coil, G2 grade, Z275 zinc coating.
• Sheet thickness: 0.6 mm to 1.0 mm by duct dimension, per AS 4254 Table 4.1.
• Pressure class: AS 4254 Class 2, design pressure 500 Pa positive and 500 Pa negative.
• Joint type: TDF (transverse duct flange) standard on main trunks, slip-on flange permitted on small branches under 300 mm.
• Sealing: SMACNA Seal Class A on supply duct (joints and seams), Seal Class B acceptable on return air.
• Insulation: External duct wrap, 50 mm glass wool with reinforced foil facing, R-value 1.3 minimum.
• Internal lining: Acoustic lining (25 mm) on diffuser plenums and the first 3 metres of supply duct after the AHU to meet NC-40 background noise. Internally lined duct uses a tear-resistant erosion barrier facing.
• Diffusers: Linear slot diffusers in luxury showrooms, square plaque diffusers in mass-market. Distribution pattern selected for low-velocity radial throw to maintain calm air column over display vehicles.

Showroom diffuser layout and the display vehicle problem

One issue specific to car showrooms — and absent from office or retail HVAC design — is that the customer experience includes a customer leaning over the bonnet of a vehicle parked under display lighting. The vehicle bonnet is 700 to 1,200 mm above floor level. The customer's head is at 1,500 to 1,700 mm. The display lighting above is at 4,500 to 6,000 mm in a typical showroom. Heat rises off the vehicle bonnet under display lighting, creating a thermal plume that drifts directly into the customer's breathing zone if the supply air does not capture and recirculate it efficiently.

This drives a specific diffuser layout. Premium dealer briefs specify a perimeter air supply strategy with linear slot diffusers at the building perimeter, throwing cool air across the room and a return air grille located high in the central zone above each vehicle display platform. The thermal plume is captured before it reaches the customer's head. The duct routing has to support this: a perimeter ring trunk fed from the AHU plant room, with branch drops to each linear slot, plus a central return air trunk dropping from the ceiling void above the vehicle display zones.

The mechanical contractor fabricating this layout on the SBAL-III auto duct line produces standard rectangular sections (typically 800 × 400 mm down to 300 × 200 mm) for the perimeter trunk, with round spiral branches (250 to 400 mm diameter) feeding the linear slot diffusers. The TDF flange ends from the auto duct line mate directly with the slot diffuser plenums, eliminating site-cut transitions and reducing acoustic leakage.

The service bay: industrial workshop ductwork in a customer-facing building

Step through the door from the showroom into the service workshop and the HVAC universe inverts. The acoustic target is NC-55 to NC-60 — industrial. The temperature target is 18 to 25°C — operationally generous, not luxurious. The dominant ventilation driver is contaminant removal: vehicle exhaust gases, oil mist, fuel vapour, brake dust, refrigerant leakage from MAC work. The ductwork is the same AS 4254 Class 2 galvanised material as the showroom, but the design intent is the polar opposite.

Service bay design conditions

• Dry bulb temperature: 18 to 25°C, generally not closely controlled. Technicians moving around lift bays generate metabolic heat; the goal is to keep the space habitable rather than comfortable.
• Air changes per hour: 6 to 10 ACH general ventilation, increased to 12 to 15 ACH where multiple vehicles run engines simultaneously.
• Source capture extraction: tailpipe exhaust extraction hose reels at every bay where engine running is routine, sized to capture full exhaust output of a passenger vehicle (typically 500 to 800 L/s per reel) and light commercial (up to 1,200 L/s).
• CO occupational exposure limit: 25 ppm eight-hour time-weighted average in the technician breathing zone per Safe Work Australia exposure standards.
• Oil mist: typically below regulatory thresholds in routine service but localised extraction at the brake lathe and at any cutting operation.
• Air conditioning refrigerant: R-134a being phased out, R-1234yf increasingly standard in new vehicles, with isolated handling of R-744 (CO₂) in some premium European vehicles. Spill management ventilation rated for the refrigerant in use.

Tailpipe exhaust extraction

The defining piece of service bay HVAC is the tailpipe extraction hose reel. Every service bay where an engine will run — for diagnostic, brake roller, dyno or pre-delivery work — has an overhead-mounted hose reel with 100 mm or 150 mm flexible hose, sealed-tip exhaust nozzle, and connection to a centralised collection trunk. The collection trunk is galvanised AS 4254 Class 2 ductwork routed at high level along the service bay back wall, terminating in a roof-mounted exhaust fan rated for the combined airflow of all simultaneously operating reels.

Sizing is by diversity factor — not all reels operate simultaneously. Industry rule of thumb is 60 to 80% simultaneous operation for a busy workshop. So a 12-bay workshop with 600 L/s per reel sizes the collection trunk for 12 × 600 × 0.7 = 5,040 L/s. The trunk grows from 200 mm round at the most-distant bay to 400 to 450 mm round at the fan inlet, with TDF flanged sections feeding each branch drop to the hose reel.

This is high-volume, moderate-pressure ductwork (typical static at fan inlet 350 to 500 Pa), well within AS 4254 Class 2. The SBAL-III auto duct line fabricates round spiral sections in 250 mm to 500 mm diameter; the rectangular plenum sections at the fan and at any header connections are fabricated on the same line in rectangular mode. A typical Australian 12-bay service workshop needs 120 to 180 linear metres of tailpipe extraction ductwork — a couple of single shifts on the SBAL-III.

General service bay ventilation

Beyond the tailpipe capture, the service bay needs general dilution ventilation to handle non-tailpipe contaminants — solvent vapour from gasket cement, refrigerant venting, brake dust, oil mist from drips at the lift, and the gradual accumulation of CO that escapes the hose reel capture. AS 1668.2 specifies industrial ventilation at 6 to 10 ACH for vehicle workshops; most dealership service bays sit at 8 ACH.

For a 600 m² service workshop at 6 m ceiling height (typical for accommodating high-roof commercial vans on a two-post lift), 8 ACH equates to 28,800 m³/h of supply air, roughly 8,000 L/s. Supplied as a tempered outside-air pre-heat in winter and direct outside air in summer, distributed through high-mounted swirl diffusers or jet nozzles that throw air down into the working zone. Return air is at high level, drawn by either dedicated return fans or relief louvres to the outside.

The supply ductwork is galvanised rectangular AS 4254 Class 2, typical sizes 800 × 400 mm or 1,000 × 500 mm dropping to 400 × 300 mm at branches, all TDF flanged. A typical service bay HVAC supply install is 200 to 300 linear metres of duct including main trunk, branches and diffuser plenum boxes. Fabricated on the SBAL-III at 60+ m/h single shift, that is three to five single shifts of duct line operation.

Panel beating and smash repair: source capture and dust collection

Where the dealership includes its own smash repair operation — or where the workshop is a standalone smash repairer like a Schmick or Capital Smart site — the HVAC scope expands again. Panel beating adds welding fume, plasma cutting smoke, oxy-acetylene cutting fume, abrasive sanding dust, metal grinding particulate and occasional aluminium dust (a combustible dust hazard under AS 5063 and NFPA 484). The smash repair shop is the bridge between general workshop HVAC and the NFPA 33 spray application area.

Welding fume capture

Every welding station — MIG, TIG and spot welding — gets an articulating arm fume extractor with a 150 mm or 200 mm hood positioned 200 to 400 mm from the welding arc. Capture velocity at the source needs to exceed 0.5 m/s to overcome the thermal plume rise from the welding arc. Arms are connected to a manifold trunk in galvanised AS 4254 Class 2 ductwork, routed to a roof-mounted fan with cartridge or HEPA filtration before discharge.

Welding fume contains metal oxides (predominantly iron, manganese, chromium for stainless welding) that fall under tightened Safe Work Australia exposure standards. The cartridge filter system needs to meet 99.5% particulate efficiency for sub-micron metal oxide aerosols. Filter housing and the upstream ductwork are at slight negative pressure (typically 800 to 1,200 Pa) which is the upper end of AS 4254 Class 2; some installations specify Class 3 (1,000 Pa) to provide headroom against filter loading.

Sanding dust and downdraft tables

Panel sanding generates the largest dust volume in the smash repair operation, primarily filler dust (polyester resin with talc filler) and primer overspray dust. The control strategy is a downdraft sanding table — a perforated steel work surface drawing air downward at 0.5 to 1.0 m/s through the panel being worked, capturing dust at the source before it disperses into the breathing zone.

The downdraft table connects to a dust collection trunk in galvanised AS 4254 Class 2 ductwork, sized for 4,000 to 8,000 L/s per table depending on table area. Multiple tables manifold into a common trunk routed to a baghouse or cartridge dust collector. The collector is positioned external to the building or in a dedicated dust collection room with explosion vent panels (NFPA 68) because polyester filler dust has been shown to be combustible at fine particle sizes.

Ductwork for dust collection has specific design requirements distinct from general HVAC. Minimum conveying velocity must be maintained throughout to prevent dust dropout: 18 to 20 m/s for fine dust like polyester filler, 22 to 25 m/s for coarse dust like aluminium grinding. This translates to small-diameter, high-velocity ductwork — round spiral 200 to 400 mm diameter, much smaller than equivalent general HVAC trunks at the same airflow. The SBAL-III auto duct line fabricates this size range efficiently in spiral mode. All dust collection ductwork includes static dissipative earthing to control electrostatic discharge from particulate-laden airflow — particularly critical where aluminium content is present.

The plasma and oxy-fuel cutting station

Heavy structural repair work — chassis rail replacement, sub-frame correction — uses plasma cutting or oxy-acetylene cutting that generates intense thermal plume and a mixture of metal oxide fume and combustion products. Capture is by a movable hood mounted on an extending boom, positioned within 600 mm of the cut. Airflow per cutting station is 1,200 to 2,000 L/s. The cutting station extract typically joins the same dust collection manifold as the sanding tables, with a separate cartridge filter set rated for higher temperature service (the cutting fume can be 60 to 120°C at capture).

The paint shop: NFPA 33 and the stainless boundary

The paint booth is the most highly regulated single space in any dealership or smash repair complex. Solvent-based paint generates flammable vapour atmospheres, the spray application area is an AS/NZS 60079 Zone 1 hazardous area, and the bake cycle introduces high-temperature exhaust that requires specific stainless steel ductwork construction. The applicable codes are NFPA 33 (Standard for Spray Application Using Flammable or Combustible Materials) and NFPA 86 (bake oven systems), referenced by Australian authorities as the de facto standard where AS does not cover the specific application.

Booth airflow and the downdraft principle

Modern automotive paint booths are downdraft design: filtered supply air enters the booth through a full-ceiling plenum at 0.3 to 0.5 m/s, sweeps downward past the vehicle, and is exhausted through a perforated floor or pit grille at the booth base. Downdraft airflow minimises overspray contamination of the painted surface (gravity pulls overspray away from the panel, not across it) and provides consistent airflow patterns for finish quality. Typical booth airflow rates: 16,000 to 24,000 m³/h for a single-car booth, scaling up for larger commercial vehicle booths.

The supply air to the booth ceiling plenum is conditioned (heated, sometimes cooled, humidified or dehumidified) outside air, ducted from an air handling unit dedicated to the booth. Supply ductwork from AHU to plenum is galvanised AS 4254 Class 2 with full sealing — leakage drops booth airflow and degrades finish quality. The supply ductwork can use standard SBAL-III fabricated sections because it carries clean conditioned air, not solvent-laden exhaust.

The exhaust boundary and the stainless requirement

The exhaust ductwork from the booth floor pit is a different story. It carries:

• Solvent vapour (xylene, toluene, MEK, ester solvents) at concentrations that can approach the lower explosive limit if booth ventilation is degraded.
• Paint overspray particulate, which deposits on the duct walls as a sticky resin layer.
• Bake-cycle exhaust at 60 to 80°C for low-bake clearcoat operations, 120 to 140°C for high-bake automotive refinish ovens.
• Cleaning chemistry residue when the booth and ductwork are periodically cleaned with solvents and proprietary booth-cleaning compounds.

This service environment rules out galvanised steel. The zinc coating is attacked by alkaline booth cleaning chemistries, the bake cycle thermally stresses any galvanic interface, and the overspray deposition is much easier to remove from a smooth stainless surface than from a textured galvanised surface. NFPA 33 paragraph 8 and Australian best practice converge on stainless steel 304 minimum, 316L for solvent-heavy refinish operations.

This is where the SBKJ machine configuration matters. The SBAL-III auto duct line is optimised for galvanised steel coil; it can run stainless but tooling life suffers because of stainless work-hardening behaviour. The SBAL-V auto duct line is configured for mixed material running, with stainless-capable tooling, modified roll-forming station pressures and a coil handling system that accommodates stainless coil's higher modulus. A dealership ductwork project of any meaningful scale runs the SBAL-III for the galvanised majority (showroom, service bay, panel area, parts warehouse) and uses an SBAL-V or a dedicated stainless line for the paint shop exhaust boundary.

Paint shop ductwork dimensions

A single passenger-vehicle paint booth needs roughly 80 to 150 linear metres of stainless exhaust ductwork: pit collection trunk, riser to roof, horizontal run to filter housing, filter housing to fan, fan discharge to stack. Sheet thickness is heavier than commercial HVAC — 1.2 to 1.5 mm stainless is typical to provide rigidity for cleaning access and to support the cyclic thermal expansion of bake cycles. TDF flanges are not used in paint shop service; the joints are welded continuous, either MIG with stainless filler or TIG for cleaner finish. The SBAL-V can roll-form the flange shapes, but the field jointing is welded rather than mechanically flanged.

Bake oven cure and the high-temperature ductwork

The bake or cure cycle is the highest-temperature service in the paint shop. After spray, the vehicle remains in the booth (combi booth) or moves to a separate bake oven where heated air at 60 to 80°C (low-bake clearcoat) or 120 to 140°C (high-bake refinish or factory finish OEM) is recirculated through the cabin for 20 to 45 minutes. The exhaust from the bake cycle is hotter than spray exhaust and contains volatile cure-byproducts at elevated concentration.

The bake exhaust ductwork is heavier-gauge stainless with insulation rated for continuous service at the maximum bake temperature plus a safety margin. NFPA 86 specifies bake oven ventilation requirements including continuous purge before ignition, high-temperature limit switches, and explosion vent panels in the bake exhaust ductwork at locations sized per NFPA 68. Australian compliance is by reference to NFPA 86 augmented by AS 1375 for industrial fuel-fired equipment.

The clearcoat cure transition

Modern refinish operations have moved progressively toward UV-cure clearcoat for spot repair work and infrared low-bake clearcoat for larger repairs, reducing the cure time and energy demand compared to high-bake. Infrared low-bake operates at 50 to 70°C and uses radiant heaters rather than circulating hot air, which simplifies the ventilation demand: the booth still needs spray-application ventilation during paint application, but the cure phase does not need high-temperature exhaust. The result for ductwork design is more linear metres of standard stainless exhaust and fewer metres of high-temperature insulated bake duct. A typical 2026 smash repair installation has 80 to 100 m of standard stainless exhaust and 0 to 30 m of high-temperature insulated bake exhaust, depending on whether the operation includes high-bake refinish capability.

AS/NZS 60079 hazardous area: where the showroom meets the forecourt

Many Australian dealerships sit on properties that include or adjoin a refuelling forecourt — manufacturer-branded pre-delivery fill, a service workshop fuel transfer station, or in some legacy sites a co-located service station. Where flammable vapour atmospheres can form, AS/NZS 60079.10.1 classifies hazardous areas:

• Zone 0: explosive atmosphere present continuously or for long periods — typically inside fuel tanks and vapour spaces. Ductwork generally does not penetrate Zone 0.
• Zone 1: explosive atmosphere likely in normal operation — typically a sphere extending 1.0 to 1.5 m radius from dispenser nozzles. Ductwork in Zone 1 must be intrinsically safe or use explosion-proof equipment.
• Zone 2: explosive atmosphere not likely, but if it occurs would persist briefly — typically a larger sphere extending 4.5 m from dispensers. Standard HVAC equipment can operate in Zone 2 with limited safety upgrades.

A typical dealership configuration has the customer pre-delivery fill station 5 to 10 metres outside the service workshop wall. The service workshop interior is generally outside any classified zone, but the wall penetrations for ductwork to the fan stacks must be sealed and any combustion devices (gas-fired AHU heaters, gas-fired boilers feeding hot water heating coils) must be sited outside Zone 2.

The implication for ductwork is modest in the typical case — galvanised AS 4254 Class 2 ductwork is unaffected by hazardous area classification because the duct interior carries clean ventilation air and the duct exterior is at most in a Zone 2 region that does not affect the duct material itself. What changes is the equipment connected to the duct: fans serving exhaust from the workshop adjacent to the forecourt are specified as spark-resistant construction (AMCA Type B minimum), and any electrical control gear in the fan room is rated EX d or EX e per AS/NZS 60079.0.

NFPA 30A: motor fuel dispensing implications

Where the dealership site includes its own fuel transfer station for delivery vehicles or includes a co-located retail forecourt, NFPA 30A applies (referenced in Australia by analogy and by state petroleum authority guidelines). NFPA 30A paragraph 4 specifies clearance distances and ventilation requirements:

• Service bays within 7.6 m of a dispenser require continuous mechanical exhaust at floor level — petrol vapour is heavier than air and accumulates at floor level. Exhaust rate typically 1 air change per minute (60 ACH) at floor level for the first 300 mm of room height.
• Open flames, including gas-fired heaters, smoking and welding operations are prohibited within 7.6 m of a dispenser. This rules out gas-fired AHU units in service bays near forecourts and pushes the design toward heat-pump-based heating with electric strip backup.
• Vehicle exhaust extraction ductwork penetrating the bay walls toward the forecourt direction needs to be checked against the dispenser exclusion zones.

The ductwork implications: floor-level exhaust requires a low-level slot or grille on each external wall, ducted to a roof-mounted fan via galvanised AS 4254 Class 2 ductwork. The duct geometry is constrained: the slot is at 50 to 200 mm above floor level (NFPA 30A specifies the capture zone for heavier-than-air vapours), so the duct trunk often runs as a baseboard chase ducted to a riser. The SBAL-III fabricates these small rectangular sections (typically 200 × 150 mm to 400 × 150 mm) efficiently.

The parts warehouse: ambient HVAC and the high-value bay

The parts warehouse is the dealership's largest single floor area in most builds — frequently 1,500 to 4,000 m² in a multi-franchise dealership, dwarfing the showroom and service bays combined. The ventilation and HVAC requirements are modest in most of the warehouse and elevated in specific bays.

General parts warehouse

The bulk parts warehouse holds mechanical parts (suspension, exhaust, brake), trim panels, body panels, accessories, oil and lubricant stock. These are not temperature-sensitive at the building envelope thermal performance level of an Australian commercial warehouse — internal temperature swings of 10 to 35°C across summer-winter cycles are acceptable for the stock and the staff working in the warehouse for short retrieval visits. AS 1668.2 specifies minimum 1 ACH ventilation for warehouse spaces with infrequent occupancy.

Ductwork: minimal. A typical warehouse install has a roof-mounted ventilation fan with stub ducts to drop ceiling diffusers at locations of higher activity (parts counter, dispatch dock). Total ductwork typically 80 to 200 linear metres in galvanised AS 4254 Class 2 round spiral or rectangular, depending on warehouse geometry.

The high-value climate-controlled bay

A growing portion of dealer parts inventory requires controlled storage. Items include:

• Paint stock: tinting bases, solvents, hardeners. Manufacturer specifications typically require storage at 15 to 25°C, away from direct sunlight, with limited humidity range. Paint tinting accuracy degrades if base paints have been exposed to temperature extremes.
• Lithium-ion battery modules: traction battery packs for EVs, plug-in hybrids and mild hybrids. Manufacturer storage specifications converge on 5 to 25°C, 30 to 70% RH, with state-of-charge held at 30 to 50% during long-term storage. Battery modules above a certain Wh threshold also trigger AS/NZS 5139 storage and hazardous goods handling requirements.
• Electronic control units, infotainment modules: humidity-sensitive PCBs. Stored at 20 to 25°C, below 60% RH.
• OEM dealer-only restricted parts: some manufacturer programmes specify climate-controlled storage as a condition of access to performance, racing or limited-edition parts.

The climate-controlled bay is typically 50 to 200 m² walled off within the larger parts warehouse, served by a dedicated AHU and ductwork delivering 22°C ± 2°C and 50% RH ± 10%. Ductwork is standard galvanised AS 4254 Class 2 — the volume is small. A typical install is 30 to 60 linear metres of small-diameter spiral and 200 × 200 mm rectangular branches feeding diffusers spaced through the bay.

The customer lounge: hospitality-grade comfort

Premium dealership corporate identity treats the customer lounge as a brand experience. Mercedes-Benz Stage III, BMW Future Retail, Audi Terminal, Lexus Premium, Genesis Studio and Volvo Studio retail formats all converge on customer waiting areas that look and feel like a five-star hotel lounge: espresso bar, seating areas, table workstations, infotainment screens, and in the most ambitious formats, a brand-themed kitchen serving light meals during longer service appointments.

Customer lounge design conditions

• Dry bulb temperature: 22 to 23°C, dead-band 0.5°C — tighter than the showroom because customers are stationary for extended periods.
• Acoustic background level: NC-35 — quieter than the showroom because customers are conversing, working on laptops, or expecting calm.
• Supply air velocity: below 0.20 m/s at occupant head height — drafts are highly perceived by stationary occupants and trigger comfort complaints.
• Outside air: 7.5 L/s per person, demand-controlled by CO₂ to maintain 600 to 700 ppm during peak occupancy.
• Kitchen exhaust: where the lounge includes a kitchen, AS 1668.2 specifies hood capture velocity and exhaust airflow. Typical lounge kitchen exhaust 1,500 to 3,000 L/s with mechanical make-up air. Ductwork to AS 1668.1 (commercial cooking equipment ventilation) for the hood ducts, AS 4254 Class 2 for supply.

Customer lounge ductwork

Standard AS 4254 Class 2 galvanised, but with elevated acoustic finish requirements. Internal acoustic lining is more common in the lounge than the showroom because the NC-35 target is harder to hit. Duct runs are kept short and direct to minimise pressure drop and reduce diffuser approach velocity. Diffusers are typically architectural linear slots (Tweed, Trox or similar premium ranges) flush-fitted into joinery. The duct fabricator's challenge in the customer lounge is producing flange ends that mate cleanly with architectural slot diffusers from European premium manufacturers — TDF flange dimensions need to match the slot plenum dimensions exactly, which is straightforward on the SBAL-III with its programmable flange profile.

Tyre and wheel alignment bay: the high-ceiling exception

Dealership service operations include tyre and wheel alignment work as a high-throughput service item. The tyre bay and the alignment bay are typically grouped together, often with higher ceilings than the general service workshop (7 to 9 m clear) to accommodate hoist-mounted alignment equipment and to provide a high-volume air space for the wheel balancer dust and abrasive grit common to the workspace.

HVAC for the tyre and alignment bay follows the general service workshop pattern (6 to 10 ACH, no source capture beyond what is already provided), with two specifics:

• Tyre dust and rubber particulate: tyre mounting and balancing generates rubber dust at low concentrations, controlled by general ventilation rather than source capture in most installations. High-volume premium dealerships sometimes add a localised extraction hood at the tyre changer.
• Infrared supplementary heating: the high ceiling makes air-temperature heating inefficient (heated air stratifies above the working zone). Most installations supplement air heating with overhead infrared radiant heaters that warm the occupants and the floor directly. The infrared heaters are not connected to ductwork but their installation affects the supply diffuser layout — diffusers cannot be located where they would short-circuit the radiant heat plume to the return air grille.

EV charging integration: the new mechanical scope

The shift toward electric vehicles has added a substantial new mechanical scope to dealership design that did not exist five years ago. Three distinct EV-related ventilation considerations now appear in every new-build dealership brief.

AC charging in the parking deck

AC charging stations at 7, 11 or 22 kW per stall are now standard in display car parks and customer parking areas of new dealerships. The thermal load per stall is modest (a 22 kW charger dissipates roughly 1.5 to 2.5 kW as heat depending on duty cycle), and the ventilation requirement is minimal — the underground or covered parking deck mechanical ventilation already in place for the AS 1668.2 minimum carpark ventilation rate is sufficient. No dedicated ductwork is needed for AC charging.

DC fast charging cabinets

DC fast chargers at 50, 150, 350 kW per stall are increasingly installed at dealership locations as customer service amenity and as service centre equipment for charging vehicles between repair stages. The DC charging cabinet (the wall-mounted unit containing the rectifier electronics) dissipates significant heat — typically 5 to 8% of the rated charging power. A 150 kW charger dissipates 8 to 12 kW; a 350 kW charger dissipates 18 to 28 kW.

This is significant cooling load and the cabinet manufacturer's installation manual usually specifies dedicated mechanical extraction of cabinet exhaust air, or air-conditioned ambient temperature within a defined range. For a bank of three to six DC chargers at 150 kW each — a common configuration at premium dealerships — total cabinet heat dissipation is 25 to 70 kW. This drives either dedicated mechanical extract ductwork drawing air from the cabinet rear exhaust ports to a roof-mounted fan, or a packaged cooling unit serving the charger room.

Where the ducted extract approach is used, the ductwork is galvanised AS 4254 Class 2 — clean air, no contamination, moderate temperature (50 to 70°C return air). Typical layout is a horizontal trunk along the rear of the charger bank, dropping to each charger's extract port through a flexible connector, rising to roof level through a stainless or galvanised riser. SBAL-III fabrication, 30 to 80 linear metres per installation.

Lithium-ion thermal runaway response

The highest-impact EV consideration is thermal runaway response planning in the high-voltage service workshop. When a damaged or defective EV battery enters thermal runaway, it generates highly toxic gas mixtures (HF, CO, smoke, volatile organic vapours), heat well in excess of 500°C, and potentially flame. The mitigation strategy in modern EV service centre design (Tesla, Polestar, Genesis, Mercedes-EQ, BMW i) includes:

• Dedicated EV bay separation: EV work isolated to specific bays with separate ventilation from the general workshop.
• Smoke evacuation ductwork: high-volume mechanical extract sized to evacuate a thermal runaway plume in under 2 minutes, typically 10,000 to 20,000 L/s per bay. Ductwork in galvanised AS 4254 Class 2 with fire-rated insulation or in stainless steel for the most exposed sections nearest the bay.
• Gas detection: HF and CO detectors with interlocks to ramp the evacuation fans on alarm.
• Vehicle isolation: some installations include a portable battery quarantine pit or a dedicated water-immersion tank for catastrophic battery events, with separate ductwork for the steam and vapour generated during quench.

This adds 40 to 100 linear metres of duct per high-voltage workshop to the dealership's ductwork scope. Increasingly specified as standard in Australian Tesla, Polestar and Genesis service centres, and being added retrospectively to legacy dealer workshops as part of EV readiness upgrades. Mercedes-Benz, BMW, Audi and Volvo dealer networks are publishing similar specifications for their EV service bays in 2025 to 2027.

Brand standards: why corporate identity drives HVAC

Australian premium dealership operators do not have unilateral design freedom. Every franchise agreement includes a Corporate Identity manual — a brand standards document that specifies architecture, finishes, lighting, signage, and increasingly, mechanical engineering performance targets. The Mercedes-Benz Stage III specification runs to several hundred pages. BMW Future Retail Design Guide is similar. Audi Terminal, Lexus Premium, Genesis Studio, Volvo Studio, Polestar Space, Porsche Centre — each has a comparable standards manual.

For HVAC, the brand standards typically specify:

• Showroom temperature and humidity bands.
• Showroom acoustic background level (NC-35 to NC-40).
• Diffuser style and placement guidelines (architectural slot diffusers in luxury brands, square plaque in mid-market).
• Customer lounge comfort specifications.
• Service workshop ventilation minima (6 to 10 ACH).
• For EV-capable brands, dedicated EV bay ventilation specifications.
• For paint-shop-enabled brands (Mercedes-Benz Approved Body and Paint, BMW Body Repair Centre, Audi Body Repair), NFPA 33 compliant paint booth performance and AS/NZS 60079 hazardous area compliance.

The mechanical engineer designing a multi-franchise dealership must reconcile the standards of multiple brand owners co-located in the same building. Often the dominant brand drives the showroom HVAC specification and the lower-tier brands inherit the result. The dealership operator pays for the highest common denominator.

Why galvanised is fine for the dealership and stainless is mandatory for the paint shop

A question the mechanical contractor will get asked repeatedly in a dealership tender: why are we paying for galvanised duct in the showroom and stainless duct in the paint shop? The answer comes down to chemistry, temperature and corrosion.

Galvanised steel (Z275 pre-galvanised coil per AS 1397) is excellent for:

• Dry, clean ventilation air at 5 to 40°C — showroom, customer lounge, parts warehouse, office areas, general service workshop supply.
• Vehicle exhaust extraction at moderate temperature (under 80°C at the duct wall) and moderate condensate exposure — tailpipe extraction trunks.
• Dust collection ductwork — sanding dust, welding fume after capture.
• EV cabinet extract — clean air.

The zinc layer (275 g/m² total both sides) provides 30 to 50 years of corrosion protection in dry interior service. Galvanised duct is fabricated at high throughput on the SBAL-III auto duct line — 60 to 80 linear metres per hour single shift — and costs roughly one-third the material cost of stainless steel duct at the same dimensions.

Stainless steel (304 or 316L) is mandatory for:

• Paint shop exhaust — solvent vapour attacks galvanised coating, alkaline booth cleaning chemistry consumes the zinc layer, overspray deposition is harder to clean from galvanised than from stainless.
• Bake oven exhaust — temperatures of 120 to 140°C are at the upper limit of galvanised service life; stainless is dimensionally stable across cyclic thermal expansion.
• Battery thermal runaway smoke evacuation — corrosive gas mixtures (HF) attack galvanised coating; stainless is preferred for the duct nearest the bay.
• Any duct expected to be cleaned with aggressive chemistry on a routine basis.

The cost premium is real — stainless coil is roughly 3 to 4 times the per-tonne cost of pre-galvanised — and the fabrication throughput is lower because stainless is more difficult to roll-form than mild steel. The SBAL-V auto duct line is configured for stainless service: hardened tooling, modified pressure curves on the roll-forming station, slower throughput (typically 25 to 40 m/h on stainless versus 60 to 80 m/h on galvanised) and a coil handling system that accommodates the higher coil weight and stiffness of stainless.

The SBKJ machine configuration for dealership ductwork

An Australian multi-franchise dealership ductwork project of typical size — 1,500 to 4,000 m² floor plate, 8 to 16 service bays, customer lounge, climate-controlled parts bay, and either a paint shop or a paint shop boundary if smash repair is contracted externally — generates 800 to 1,500 linear metres of duct in total. The breakdown by material:

• Galvanised AS 4254 Class 2 — 80 to 90% of total length: showroom supply and return, customer lounge, service bay supply and tailpipe extraction, panel area extraction trunks, parts warehouse ventilation, climate-controlled bay HVAC, EV cabinet extract, office and admin HVAC.
• Stainless steel 304 or 316L — 10 to 20% of total length: paint booth exhaust if on-site, bake oven exhaust, battery thermal runaway evacuation if specified, high-temperature exhaust above 80°C wall temperature.

The SBKJ machine pairing that handles this scope:

• SBAL-III auto duct line — galvanised production: 60 to 80 linear metres per hour single shift on galvanised coil. Width range 1,000 to 1,500 mm coil, thickness 0.5 to 1.5 mm. TDF flange end-forming integrated. PLC controlled. Three to five single shifts of operation completes the galvanised majority of a typical dealership project.
• SBAL-V auto duct line or stainless-capable line — stainless production: 25 to 40 linear metres per hour on stainless 304/316L. Hardened tooling, modified pressures, integrated flange-forming for the field-welded joints. One to two single shifts completes the stainless paint shop boundary.

A two-line SBKJ shop (one SBAL-III, one SBAL-V) completes the duct fabrication for a multi-franchise dealership in 18 to 22 single shifts total — roughly four working weeks for a single fabricator at single-shift operation, or two working weeks at double-shift on the SBAL-III with stainless work scheduled into normal hours. This timeline aligns with typical mechanical contractor build sequences in Australia: fabrication runs in parallel with site civil and structural work, with first duct deliveries landing on site at trades start.

Coil specification and procurement

The SBAL-III runs Z275 pre-galvanised mild steel coil per AS 1397 in widths 1,000 mm, 1,250 mm and 1,500 mm and thicknesses 0.5 mm to 1.5 mm. Australian-supplied coil from BlueScope or Liberty Primary Steel is commonly used. The SBAL-V runs stainless coil in widths up to 1,250 mm at 0.6 mm to 1.5 mm — 304 or 316L grade depending on the paint shop chemistry. Coil is procured in slit form to the exact width needed for the largest duct size in the run, with smaller ducts cut from the same slit coil.

Tooling and accessories

The dealership project mix benefits from a stocked tooling library covering:

• TDF flange formers in 20, 25, 30 mm flange heights.
• Pittsburgh seam roll-formers for longitudinal joints.
• Snap-lock formers for round spiral branches.
• Slip-joint formers for small flexible branches.
• Flange-corner stampers for TDF four-bolt corners.

The SBAL-III ships with the full TDF flange suite as standard. The SBAL-V adds stainless-rated tooling versions of the same. Round spiral capability on either line is via a quick-change forming station.

Project timeline and procurement reality

A typical Australian dealership ductwork project runs the following timeline from initial brief to commissioning:

• Weeks 1 to 4: mechanical design, AS 1668.2 calculations, brand standards review, paint shop NFPA 33 design if applicable, hazardous area drawing set if forecourt-adjacent.
• Weeks 4 to 8: shop drawings, coordination with structural and electrical, BIM clash detection. Duct contractor pricing and procurement of coil stock.
• Weeks 8 to 14: fabrication on SBAL-III for galvanised majority, on SBAL-V for stainless paint boundary. Total 18 to 22 single shifts of duct line operation, spread across calendar weeks to match site delivery slots.
• Weeks 12 to 22: site installation, threaded through the building trades sequence — duct typically lands after structural steel and concrete slab completion, before architectural ceilings.
• Weeks 22 to 28: mechanical commissioning, balancing, paint booth performance testing, brand standards compliance verification, hand-over.

This timeline is rarely compressed below 16 weeks total even for a fast-track project. The bottleneck is rarely duct fabrication itself — a two-line SBKJ shop can fabricate the duct in 3 to 4 calendar weeks — but the site sequence and the long-lead items (AHUs, chillers, paint booth pre-fab modules, high-voltage switchboards) that gate the install start.

Cost and budgeting reality for the duct contractor

Without quoting specific pricing, the structural cost pattern for dealership ductwork is well-known to Australian duct contractors:

• Material cost (coil and accessories): roughly 35 to 45% of the fabricated duct cost. Galvanised coil price fluctuates with steel commodity markets; stainless is much more volatile and weighted in the paint shop scope.
• Labour cost (fabrication and installation): roughly 40 to 50%. Australian metro labour rates for sheet metal fabrication and installation are among the highest in the Asia-Pacific region.
• Machine depreciation, tooling, energy, factory overhead: roughly 10 to 15%.

The lever that moves the largest cost number is fabrication labour. A single-shift SBAL-III on galvanised coil produces 60 to 80 m/h of finished, flanged, ready-to-install duct with one operator and one assistant — a labour productivity that classical hand-fabrication of the same duct cannot approach (manual fabrication is typically 8 to 15 m/h per fabricator). The auto duct line is the single largest productivity multiplier in the duct contractor's shop.

The implication for procurement on a dealership project: the duct contractor with auto duct line capability has a structural cost advantage of 20 to 35% on the labour-intensive bulk-fabrication portion of the scope. On a project where bulk fabrication is the majority of the total duct length, this advantage is decisive in competitive tendering.

Common HVAC ductwork mistakes on dealership projects

Patterns we see repeatedly when called in to remediate dealership ductwork after handover:

Mistake 1 — under-sized tailpipe extraction trunk

The mechanical engineer sized the tailpipe trunk for 50% simultaneous reel operation, but the workshop runs at 80%+ during busy mornings. CO levels rise above the OEL by 10:30 am. The fix is replacing the fan and uprating the trunk — expensive after handover, trivial at design stage. Rule of thumb: size the tailpipe trunk for 70 to 80% simultaneous operation on a workshop above 8 bays.

Mistake 2 — galvanised duct in the paint shop exhaust

The duct contractor saved 30% on the paint shop scope by specifying galvanised instead of stainless. Within 18 months the booth exhaust duct shows corrosion, alkaline booth-cleaning chemistry has attacked the zinc, and the duct interior is gathering deposit. The fix is full replacement in stainless — 4 to 6 times the original saving. Specify stainless from the start.

Mistake 3 — no fire dampers at the showroom-to-workshop wall penetration

The showroom and workshop are different fire compartments under the National Construction Code Class 6 (retail) and Class 8 (workshop) classifications. Ductwork penetrating the dividing wall needs fire and smoke dampers per AS 1668.1 and AS 1851. Missing dampers fail building handover certification and require retrofit cutting-in. Spec at design stage.

Mistake 4 — NC-40 target met at the AHU but exceeded at the diffuser

The AHU is acoustically rated at NC-35 at 3 metres but the diffuser at the customer's head is reading NC-45 due to in-duct turbulence and high diffuser approach velocity. The fix is internal acoustic lining on the last 3 metres of duct before each diffuser and a lower-velocity diffuser selection. Spec internal lining as standard on the supply duct to all customer-facing zones.

Mistake 5 — climate-controlled parts bay too small

The original brief allocated 30 m² for paint, battery and ECU stock. By year three the climate-controlled stock has grown to 70 m² and the bay is overflowing into the general warehouse. The fix is enlarging the bay envelope (carpentry work) and uprating the AHU — moderate cost if planned. Spec 50 to 100% more climate-controlled area than the day-one requirement on a new build.

Mistake 6 — EV cabinet extract not coordinated with charger procurement

DC charger cabinets vary by manufacturer in their extract port location, dimensions and required airflow. Ductwork installed before the charger model is finalised needs to be cut and rerouted. Coordinate the charger procurement schedule with the mechanical install schedule, or design the extract trunk with universal pickup points and flexible final connections.

The 2026 outlook: EV proportion, panel shop consolidation, regulatory direction

Three trends are shaping dealership HVAC design over the next five years.

First, the EV proportion of new vehicle sales in Australia is climbing from roughly 8 to 10% in 2024 toward 25 to 40% by 2030 under current state-level zero emission vehicle targets. Each new EV adds a battery thermal management interface that the dealership service workshop must accommodate, and each new DC fast charger adds 5 to 25 kW of waste heat to extract. Dealership designs initiated in 2026 are being specified for 30%+ EV throughput by year five, which drives larger high-voltage workshop bays, more DC charger cabinets, and proportionally more EV-related ductwork scope.

Second, panel shop consolidation continues. Capital Smart Repairs, Schmick Smash Repairs and the major insurance-linked networks (Suncorp Capital Smart, IAG Repair Centres) are absorbing the independent panel shop market. The consolidated operations standardise paint booth equipment, dust collection capacity and ventilation rates, which standardises the duct contractor's scope. The independent SCA (Star Combined Auto) cooperative offers an alternative path for family-owned smash repairers but operates under similar technical baselines.

Third, regulatory direction is tightening. The 2025 update to AS 1668.2 introduces revised ventilation rates and demand-control provisions. Safe Work Australia exposure standards for welding fume, diesel particulate and brake dust have tightened and continue to do so. The state-level EPA frameworks are increasingly requiring continuous monitoring of paint booth VOC emissions. Each tightening adds a small element to the duct contractor's scope — sensors, dampers, monitoring tap-points — and reinforces the case for purpose-built auto duct lines that produce repeatable accessory connections at scale.

How SBKJ supports the Australian dealer ductwork market

SBKJ Group's customer base in the Australian automotive ductwork market consists of three layers:

• Tier 1 — large mechanical contractors with dedicated duct fabrication shops: typically operate one SBAL-III and one SBAL-V for the galvanised and stainless mix, completing 8 to 20 dealership projects per year as part of a broader commercial HVAC portfolio.
• Tier 2 — specialist duct contractors with single-shift auto duct line shops: typically operate one SBAL-III or one SBAL-IV machine, subcontract stainless paint shop work to a specialist, and complete 4 to 10 dealership projects per year.
• Tier 3 — emerging contractors expanding from sheet metal fabrication into auto duct lines: typically buying their first auto duct line to break into the commercial HVAC market, often starting with a Tier 1 mechanical contractor as a foundation customer.

SBKJ supports all three tiers from the Box Hill North VIC headquarters in Melbourne. Direct technical support is available from the Australian office — sales engineering, application support, spare parts and 72-hour remote support response. Field service support for installation and commissioning of new auto duct lines is dispatched from the SBKJ engineering team. Spare parts are held in Box Hill North for the most-used wear items, with airfreight backup for build-to-order items.

For the duct contractor preparing a bid on a multi-franchise dealership or smash repair project, the engineering scoping process typically runs:

• Initial scope review: floor plans, brand standards reference, paint shop yes/no, EV scope.
• Duct length and material breakdown: galvanised and stainless metres, accessory count.
• Machine capacity check: SBAL-III throughput for galvanised, SBAL-V for stainless, calendar weeks of fabrication.
• Material specification: AS 4254 Class 2, coil width and thickness range, TDF flange dimensions.
• Tooling check: any specialist accessories beyond the standard library.
• Quotation: bare machine, tooling kit, installation, training, commissioning, spare parts.

This scoping cycle takes one to two weeks. For an established SBKJ customer, the cycle is faster because the machine fleet capability is already known.

Talk to SBKJ Engineering about dealership and smash repair ductwork fabrication →

FAQ

What ductwork standard applies to Australian automotive dealerships and service centres?

The customer-facing showroom, customer lounge and parts office are commercial-grade spaces designed under AS 1668.2 with AS 4254 Class 2 galvanised ductwork. The service bay, panel beating area and paint booth are industrial-grade workshops requiring 6 to 10 air changes per hour, vehicle exhaust capture meeting CO occupational exposure limits, and NFPA 33 compliant spray booth construction with AS/NZS 60079 hazardous area classification where flammable atmospheres can form.

Does a dealership service bay need stainless steel ductwork?

For the general service bay, no — AS 4254 Class 2 galvanised ductwork is the industry standard and the SBAL-III auto duct line fabricates it efficiently. Stainless steel is mandatory only for the paint booth exhaust plenum and any duct carrying solvent vapour or paint overspray under NFPA 33. Most Australian multi-franchise dealer sites run 80 to 90% galvanised ductwork by length and reserve stainless for the paint shop boundary.

What temperature should a luxury car showroom maintain?

Premium dealership brand standards typically mandate showroom design conditions of 22 to 24°C dry bulb, 45 to 55% relative humidity, NC-40 background noise level and supply air velocities below 0.25 m/s at occupant head height. These are hospitality-grade targets — equivalent to a four-star hotel lobby — not industrial workshop comfort levels.

Do panel beating and smash repair shops need different HVAC to a service bay?

Yes. A general service bay deals primarily with vehicle exhaust gases captured with tailpipe extraction and a moderate general ventilation rate of 6 to 10 ACH. A panel beating shop adds welding fume, plasma cutting smoke, sanding dust and abrasive particulate that require source-capture extraction arms, downdraft sanding tables and a dust collection system separate from the general HVAC. The two systems share AS 4254 Class 2 ductwork but the panel area needs higher capture velocities and HEPA or cartridge filtration before exhaust.

How does HVAC ductwork integrate with EV service in modern dealerships?

EV service adds three new considerations. AC charging at 22 kW per stall adds modest heat load. DC fast charging at 50 to 350 kW per stall generates substantial cabinet waste heat requiring dedicated mechanical ventilation. Lithium-ion thermal runaway response planning at high-voltage workshops requires smoke and gas evacuation ductwork with higher fire ratings, typically AS 4254 Class 2 with fire-rated insulation. Tesla, Polestar, Genesis and Mercedes-EQ service centres in Australia are specifying these enhancements as standard from 2025 onwards.

Why use SBKJ machines for fabricating automotive dealership ductwork?

An Australian multi-franchise dealership project typically needs 800 to 1,500 linear metres of AS 4254 Class 2 rectangular galvanised duct plus 80 to 150 metres of stainless duct at the paint shop boundary. The SBAL-III auto duct line forms the galvanised majority at 60 to 80 metres per hour single shift with TDF flange-ready ends, and the SBAL-V stainless-capable line fabricates the paint booth exhaust duct on the same shop floor. This single-supplier fabrication approach is used by SBKJ duct contractor customers servicing Eagers Automotive, Peter Warren Automotive, Autosports Group, Sime Darby Motors Australia, Lei Shing Hong, Sutton Group, Schmick Smash Repairs and Capital Smart Repairs networks across Victoria, New South Wales and Queensland.