Why supermarket HVAC is unlike any other retail HVAC
A modern Australian supermarket is the densest collection of conflicting thermal requirements you will find under any single roof. Walk a typical Woolworths or Coles full-line store from front to back and you pass through eight to twelve thermally distinct zones in 60 metres — chilled produce holding 12 to 16 degrees Celsius at high humidity, frozen aisles with discharge air below minus 22, dairy and deli at 2 to 4, sushi prep at 8 to 12, fresh seafood at 1 to 4 over flake ice, butchery prep at 4 to 8, bakery at 26 to 30 with flour dust and proofer humidity hitting 80 percent relative humidity, rotisserie and hot-food bar above 30 with grease-laden vapour, dry grocery at 22 to 24, customer comfort at 22 to 24 with summer cooling load dominated by people and lighting, back-of-house storage and receiving running to ambient, and a plant deck on the roof that has to reject heat from refrigeration, kitchen exhaust and store HVAC simultaneously.
Office HVAC has none of these constraints. A single AHU, a few VAV boxes, ducts to ceiling diffusers and the job is done. A supermarket has eight thermal envelopes operating simultaneously, with 200 to 600 metres of refrigerated cabinet face spilling cold air into customer aisles, with grease ducts crossing fire compartments, with dust extraction running parallel to fresh air supply, with heat recovery from refrigeration condensers feeding store heating, and with a public-facing customer comfort target that has to hit 22 to 24 degrees regardless of summer ambient at 38 or winter ambient at 2.
The energy intensity tells the story. A typical Australian full-line supermarket runs an energy use intensity of 1,000 to 2,500 kilowatt-hours per square metre per year — five to eight times an A-grade office building of the same floor area. Refrigeration typically accounts for 50 to 60 percent of that, HVAC for 20 to 30, lighting 10 to 15 and other loads (signage, point-of-sale, IT, cleaning equipment) the remainder. Every HVAC duct decision interacts with refrigeration energy because the two systems share the air mass of the store. Get the supply diffuser velocity wrong above an open multideck cabinet and you push refrigeration energy up by 15 to 30 percent without ever touching the refrigeration system.
That is why supermarket HVAC ductwork is its own discipline. The rules a contractor learns on offices and warehouses do not transfer cleanly. This guide is the engineer-led reference SBKJ uses with our duct contractor customers across Australia and New Zealand who fabricate sheet metal for Woolworths, Coles, ALDI, IGA, Bunnings, Costco and the convenience-store networks.
The Australian supermarket landscape — operators, formats and duct implications
Australia's grocery sector is dominated by two majors with smaller chains, hard discount, member warehouse and independents filling the rest. Each operator has a different store format, fitout standard and HVAC duct package. A duct contractor pricing supermarket work in 2026 needs to know the playbook for each.
Woolworths Group
Woolworths Group operates Woolworths supermarkets (full-line, 3,500 to 5,500 square metres typical), BIG W discount department stores, Dan Murphy's liquor barns, BWS bottle shops, and the smaller Woolworths Metro convenience format. New Woolworths supermarket fitouts run a standardised mechanical specification with rooftop AHUs, ducted supply to perimeter linear diffusers, return through ceiling grilles, dedicated outdoor air handling, and demand-controlled ventilation tied to in-store CO2 sensors. Galvanised G90 mains run typically 8,000 to 12,000 kilograms per store, with 600 to 1,200 kilograms of 304L stainless for fresh-food prep zones. Woolworths Group's Sustainability Plan targets 100 percent renewable electricity by 2025 and natural-refrigerant transition for new stores — duct contractors should expect heat-recovery branches from gas coolers into AHU heating coils on every new build.
Coles Group
Coles Group operates Coles supermarkets (full-line, similar footprint to Woolworths), Liquorland neighbourhood bottle shops, First Choice Liquor warehouses, and Vintage Cellars premium wine. Coles has publicly committed to 100 percent CO2 transcritical refrigeration by 2030 — every new Coles fitout from 2024 onwards uses CO2 transcritical with integrated heat recovery, and the existing fleet is on a planned replacement programme. The HVAC duct implications are significant. Heat-recovery ductwork from CO2 gas coolers into AHU heating coils and domestic hot water becomes a standard branch. Rooftop equipment layouts shift — gas coolers replace condensers, often with smaller footprint but higher rejection temperature. Duct contractors pricing Coles work in 2026 should be quoting heat-recovery branches as a line item.
ALDI Australia
ALDI runs a hard-discount format with a compact footprint — 1,200 to 1,800 square metres typical — and a deliberately limited range. The HVAC duct package is correspondingly smaller: 4,000 to 6,000 kilograms galvanised, 200 to 400 kilograms stainless for the in-store bakery and butchery if the store has one. ALDI's standard fitout cycle is shorter than Woolworths or Coles — 6 to 9 weeks from shell handover — which puts pressure on the duct contractor to fabricate fast and install in a short window. ALDI's continued expansion across Australia means there is steady volume for contractors who can meet ALDI's fitout programme.
IGA, Metcash and the independent network
The IGA brand sits under Metcash, which also owns the Mitre 10 and Total Tools hardware brands, and the Foodland brand in South Australia. IGA stores range from 800-square-metre neighbourhood format to 4,000-square-metre IGA X-press flagships. Fitouts vary widely — small IGAs run minimal HVAC packages, X-press flagships approach Woolworths or Coles complexity. Duct contractors building for IGA franchisees rather than corporate Metcash work to a mix of generic AS 1668.2 specs and individual operator preferences.
Costco Australia
Costco operates a warehouse-club format with footprints of 12,000 to 15,000 square metres — three to four times a standard supermarket. The HVAC duct package scales accordingly: 25,000 to 40,000 kilograms galvanised on a typical Costco. Costco runs an in-store bakery, butchery, deli and food court — the food-zone stainless duct package alone runs 2,500 to 4,000 kilograms. The high ceiling height (often 10 to 14 metres clear) and warehouse roof structure changes the duct routing — large-diameter spiral round duct runs become a major part of the supply distribution.
Foodworks, Drakes, Romeos, Ritchies SUPA IGA, Harris Farm Markets
The independent and regional chains — Foodworks, Drakes Supermarkets (South Australia and Queensland), Romeos (NSW and Victoria), Ritchies SUPA IGA (Victoria), and the Harris Farm Markets fresh-food specialists in NSW — fill the gap between the majors and the smallest IGAs. Format varies by operator but most run 1,500 to 4,000 square metres with strong fresh-food emphasis. Harris Farm in particular runs a high stainless-duct ratio because the model is built around fresh produce, butchery, deli and bakery rather than packaged grocery. Duct packages of 5,000 to 9,000 kilograms galvanised and 600 to 1,200 kilograms stainless are typical.
Hardware, home and department-store HVAC — the adjacent retail vertical
Many duct contractors who build supermarkets also build the adjacent retail formats — hardware, home improvement, department stores and discount variety. The HVAC duct work is simpler (no refrigerated cabinets, fewer thermal zones) but the volumes are large.
Bunnings
Bunnings (Wesfarmers) operates Australia's largest hardware and home-improvement chain with warehouse-format stores typically 8,000 to 14,000 square metres. The HVAC duct package is dominated by long galvanised supply trunks running the length of the warehouse floor with high-throw drum diffusers, plus an outdoor garden and timber yard which is often only partially conditioned. Duct kilograms run 15,000 to 25,000 galvanised, with minimal stainless. The fitout programme is tight — Bunnings opens stores on a planned schedule and any duct delay risks the opening date. Spiral round duct in 800 to 1,200 millimetre diameter is common for the trunk distribution because it takes static at lower gauge weight than rectangular.
Mitre 10, Total Tools and Sydney Tools
Mitre 10 (Metcash) and Total Tools (Metcash) run smaller hardware-format stores typically 1,500 to 4,000 square metres. Sydney Tools runs trade-supply stores. HVAC duct packages run 3,000 to 8,000 kilograms galvanised. The fitouts are simpler than Bunnings but the operators run regional rollouts so volume is steady.
Officeworks
Officeworks (Wesfarmers) runs office-supply and stationery stores typically 1,500 to 3,000 square metres. HVAC is closer to office than to supermarket — straight retail ductwork with no refrigeration interaction.
Department stores — Myer, David Jones, BIG W, Kmart, Target
Myer (full-line department), David Jones (premium, Country Road Group), BIG W (Woolworths Group, discount), Kmart Australia (Wesfarmers, discount) and Target Australia (Wesfarmers, mid-market) operate department-store formats from 4,000 to 12,000 square metres. HVAC duct work mirrors a large supermarket without the refrigeration package — large galvanised mains, perimeter and central diffuser distribution, food-court back-end where present (Myer and David Jones flagships often include food halls). BIG W and Kmart frequently co-locate with Woolworths and Coles supermarkets in Westfield and Vicinity centres, so duct contractors often quote both packages on the same site mobilisation.
Discount variety and lower-end formats
Reject Shop, Best&Less and the various discount-variety operators run small-footprint stores in shopping-centre tenancies. HVAC ductwork is often shopping-centre supplied with tenant connections only. Duct contractors quote smaller scopes — typically under 1,000 kilograms galvanised — for the connection from the centre's central plant to the tenant ceiling diffusers.
Convenience and petrol-station retail — small format, high mix
Convenience retail compresses a mini-supermarket into 100 to 400 square metres. The HVAC complexity per square metre is among the highest of any retail format — chilled drinks cabinets, ice cream freezers, hot food cabinets, coffee bar, customer comfort and back-of-house all in one tenancy.
7-Eleven Australia
7-Eleven runs more than 750 stores nationally on a standardised fitout. The HVAC duct package is small — 400 to 800 kilograms galvanised — but the integration with refrigerated cabinets, the coffee station, the hot-food cabinet and the in-store bakery (in larger sites) requires careful diffuser placement. Stainless duct work runs 50 to 150 kilograms for the food prep zone. 7-Eleven's national rollout means consistent volume for duct contractors with a pre-built kit.
Ampol Foodary, BP Wild Bean Cafe
Ampol's Foodary format (formerly Caltex Foodary) and BP's Wild Bean Cafe push petrol-station retail into food-on-the-go territory — barista coffee, fresh-prep sandwiches, hot pastries, pizza by the slice. HVAC duct packages run 600 to 1,200 kilograms galvanised plus stainless for the food prep zone. NFPA 96 grease duct applies for any cooking equipment generating grease vapour — pizza ovens and hot-food fryers are the common triggers.
EzyMart, Night Owl and the independent convenience network
The independent convenience network runs small footprints with simpler HVAC packages — minimal stainless, no NFPA 96 grease duct in most cases. Duct contractors quote these as small fitouts with quick fabrication turnaround.
Standards governing supermarket HVAC ductwork
A supermarket fitout is regulated under more standards than almost any other retail format. The standards stack vertically — building code, mechanical ventilation code, food premises code, fire code and energy code all apply simultaneously, plus operator-specific specifications layered on top.
Australian Standards
- AS 1668.2 — The Use of Ventilation and Airconditioning in Buildings, Part 2: Mechanical Ventilation. Sets minimum outdoor air rates by occupancy type, exhaust requirements for kitchens, toilets, food preparation areas, and the calculation methodology for ventilation system design. The benchmark code for any Australian supermarket HVAC design.
- AS 4674 — Design, Construction and Fit-out of Food Premises. Section 3 governs ventilation systems, ductwork construction, surface finishes and cleanability in food preparation areas. Specifies smooth internal surfaces, sealed joints, accessible cleanouts, and prohibits internal duct insulation in food zones.
- AS 1530.4 — Fire Resistance Tests of Building Construction Elements. Governs fire-rated ductwork including smoke exhaust ducts, ducts crossing fire compartments and stairway pressurisation systems. Specifies the FRL (fire-resistance level) testing procedure.
- AS/NZS 4254 Parts 1 and 2 — Ductwork for Air Handling Systems. Part 1 covers flexible duct, Part 2 covers rigid sheet metal duct construction including pressure classes, leakage classes, gauges, joints and reinforcement. The duct fabricator's primary reference standard.
- AS 4323.5 — Stationary Source Emissions, Method 5: Determination of Particulate Matter. Used in conjunction with leakage test methodologies referenced from DW/143.
- National Construction Code Volume One Section J — Energy Efficiency. Sets minimum insulation thicknesses for ducts in unconditioned spaces, sealing requirements, and overall HVAC system efficiency benchmarks.
Imported reference standards
- ASHRAE 62.1 — Ventilation for Acceptable Indoor Air Quality. Frequently cross-referenced in Australian supermarket specifications for ventilation rate calculations and IAQ verification, particularly for projects funded or anchored by international developers.
- ASHRAE 90.1 — Energy Standard for Buildings Except Low-Rise Residential. Used for energy efficiency benchmarks where a project targets LEED or international green-rating systems alongside Australian compliance.
- NFPA 96 — Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations. The default international standard for commercial kitchen exhaust hoods, grease ducts and fire suppression. Used in conjunction with Australian fire code for hot-food zones in supermarkets, food courts and quick-service kitchens.
- NFPA 484 — Standard for Combustible Metals. Applied to combustible-dust handling in bakery flour-extraction systems and in-store grain mills.
- FSANZ Food Standards Code Chapter 3 — Food Safety Standards. Australia and New Zealand's binding code for food premises hygiene including ventilation, surface materials and pest exclusion.
- AHRI 1280 — Performance Rating of Walk-In Coolers and Freezers (used in conjunction with supermarket refrigerated cabinet ratings) and the AHRI standard for refrigeration heat-rejection equipment that interfaces with HVAC ductwork.
Operator-specific specifications
On top of the regulatory stack, every major operator publishes a mechanical specification document that supplements or overrides default code requirements. Woolworths and Coles run detailed mechanical specs that call out specific diffuser models, duct leakage classes (typically Class C as default, Class B for premium projects), insulation R-values above NCC minimum, and demand-controlled ventilation rules. ALDI's spec is shorter but prescriptive on rooftop equipment standards. Duct contractors building for a major need to read the operator's mechanical spec carefully — it changes from year to year and minor revisions can shift the duct package weight by 10 to 20 percent.
HVAC interaction with refrigerated cabinets — the critical design discipline
Open multideck refrigerated cabinets — the vertical chillers used for dairy, deli salads, ready meals, soft drinks and sometimes meat — are the single largest reason supermarket HVAC is harder than any other retail HVAC. Each cabinet pulls cold air from a back evaporator coil, discharges it across the top of the open face downward in a thin curtain, captures it at a return grille at the bottom of the case face, and recirculates. The air curtain is typically 60 to 120 millimetres thick at the top discharge, falls at 0.3 to 0.6 metres per second, and holds product at 2 to 5 degrees Celsius behind the curtain. The curtain is the only thing separating cold product from warm aisle air.
Anything the HVAC system does that disrupts the curtain dumps cold air into the aisle, raises product temperature and forces the cabinet to work harder. The empirical relationship is steep — laboratory and field studies consistently show 15 to 30 percent additional cabinet refrigeration energy when air-curtain disruption is severe, with proportional reductions in product shelf life and food safety margin. The HVAC supply diffusers in the aisle adjacent to the cabinet are the most common source of disruption. A standard ceiling diffuser at 1.5 to 2.5 metres per second face velocity, located directly above or in front of the cabinet, will measurably degrade curtain stability. The mitigation is engineered into the duct and diffuser design.
Mitigation strategy 1 — low-velocity supply diffusers
The default fix is to specify diffusers with face velocity below 0.5 metres per second in any aisle adjacent to refrigerated cabinets, and to locate diffusers at least 1.5 metres horizontally from the cabinet face. Linear slot diffusers running along the aisle ceiling are a common choice — they spread the supply air across a long throw rather than dumping a concentrated jet near the cabinet. Larger duct cross-sections at the diffuser take-offs keep velocity low. The duct package therefore runs slightly heavier in gauge and slightly larger in cross-section than a comparable office HVAC layout.
Mitigation strategy 2 — displacement ventilation in produce zones
For produce zones, where humidity is naturally high (produce respires moisture) and supply temperature can be moderate, displacement ventilation is increasingly specified. Cool supply air enters at low level (floor-mounted diffusers or low sidewall) at 0.2 to 0.3 metres per second, fills the lower stratum slowly, rises through buoyancy as it warms, and exits at high return. The system avoids horizontal jet velocities entirely at cabinet face level, which preserves cold curtains on adjacent multideck displays. The duct package needs low-level distribution — often a continuous plenum running the floor perimeter — and the architecture has to accommodate the floor outlets without creating trip hazards.
Mitigation strategy 3 — dedicated outdoor air system (DOAS)
A dedicated outdoor air system decouples the fresh-air ventilation function from the sensible cooling function. A separate air handler conditions outdoor air to neutral or slightly cool supply temperature and delivers it through small ducts to in-store registers, while the bulk sensible cooling is handled by separate recirculating fan-coil units or a low-velocity displacement system. The advantages for supermarkets are precise humidity control (critical for cold-curtain stability — high humidity loads cold curtains heavily), independent ventilation rate control (DCV based on customer occupancy without disturbing cooling), and energy savings on sensible cooling because the recirculation system is not over-cooling to handle latent loads.
The integrated design conversation
The refrigeration vendor, the HVAC consultant and the duct contractor have to be in the same design conversation early. The cabinet vendor knows the cold-curtain physics for their specific cabinet model. The HVAC consultant knows the supply jet trajectories. The duct contractor knows what is fabricable in the time available. Retrofitting after the cabinets are installed and the ductwork is up is significantly more expensive than getting the layout right at design stage. SBKJ recommends a joint review at 60 percent design development for any new supermarket — three parties around one floor plan with the cabinet schedule overlaid on the duct layout.
Refrigeration heat rejection and HVAC heat recovery
Supermarket refrigeration runs all day every day. The system rejects heat to atmosphere via rooftop condensers (HFC and older systems) or gas coolers (CO2 transcritical). That rejected heat is in the order of 200 to 600 kilowatts continuous for a full-line supermarket — enough to heat the store many times over in winter and to provide all the domestic hot water. Capturing that heat into the HVAC system is one of the highest-return energy-efficiency moves in supermarket design.
HFC condenser heat recovery (legacy systems)
Older HFC systems running R-404A or similar reject heat at relatively low condensing temperature — typically 35 to 40 degrees Celsius. Heat recovery from HFC condensers feeds glycol loops at modest temperatures, which limits recovered-heat utility to space heating and pre-heating domestic hot water. Many 1990s and 2000s Australian supermarkets ran no heat recovery at all because the economics were marginal at the available temperatures.
CO2 transcritical heat recovery (current and future)
CO2 transcritical refrigeration runs the upper part of the cycle at supercritical pressure — there is no defined condensing temperature. Heat is rejected at gas cooler outlet temperatures of 35 to 45 degrees Celsius routinely, and the gas cooler inlet is much hotter (90 to 110 degrees). That higher-temperature heat source unlocks much better recovery economics. A CO2 transcritical supermarket can typically meet 100 percent of its space heating load and 80 to 100 percent of its domestic hot water load from refrigeration heat recovery alone, with electric or gas backup only in deep winter peaks. The HVAC duct implications are heat-recovery branches from the gas cooler (or a desuperheater intermediate exchanger) into AHU heating coils, with control logic to modulate between recovery and direct gas-cooler rejection based on heating demand.
Cascade CO2-ammonia and other natural refrigerants
For larger sites, cascade systems pair CO2 (R-744) for low-temperature loads with ammonia (R-717) for high-temperature loads — leveraging the strengths of both natural refrigerants. Heat rejection is at higher temperatures still and recovery economics improve further. The HVAC interface is similar to pure CO2 transcritical but with multiple rejection circuits and slightly different control logic.
Practical duct work for heat recovery
The heat-recovery branch from refrigeration into HVAC is typically a glycol loop with a plate heat exchanger at the gas cooler and a coil in the AHU return air or supply path. The duct contractor's scope is to design and fabricate the AHU coil mounting, the upstream and downstream duct, access doors for coil cleaning and the bypass damper for periods when heat recovery is not needed. Galvanised G90 is appropriate for this duty — it is general HVAC, not food contact.
Bakery HVAC — flour dust, oven exhaust, proofer humidity
An in-store bakery is its own HVAC sub-discipline within the supermarket. The five distinct streams are oven exhaust, proofer humidity, flour-dust extraction, customer-facing display HVAC and the staff working environment.
Oven exhaust under NFPA 96 and AS 1668.2
Convection ovens, deck ovens and rotary rack ovens generate exhaust at high temperature with low to moderate grease loading depending on what is baked. Pure bread and pastry baking generates minimal grease — the exhaust runs hot and humid but does not require liquid-tight welded grease duct. Bakery items with high fat content (butter croissants, certain pastries) move closer to the NFPA 96 grease threshold. The default specification is a Type II hood (heat and steam, not grease) with galvanised or stainless duct, sloped to a drain, terminating at a roof exhaust fan with isolation damper. For higher-fat product mixes, specifying a Type I hood and NFPA 96 grease duct is the safer choice.
Flour-dust extraction under NFPA 484
Flour is a combustible dust. A properly engineered bakery has a dedicated flour-dust extraction system with point-of-source capture at the dough mixer, the flour silo discharge, the moulder, the divider and any other process equipment that generates airborne flour. The extraction ducts run to a baghouse or cyclone-baghouse combination, with the collected dust returned to the silo or disposed of safely. NFPA 484 (combustible metals — analogous code provisions apply for combustible food dusts) requires explosion venting on the dust collector, conductive duct construction with bonded grounding, and isolation between the dust collection and any potential ignition source. The dust ducts are typically galvanised, smooth-bore, generously sized to keep transport velocity in the 18 to 25 metres per second range.
Proofer humidity control
Bread proofing rooms run 26 to 35 degrees Celsius at 60 to 80 percent relative humidity. The combination of warm temperature and high humidity is aggressive on duct material — galvanised steel will pit and corrode within a few years. The default specification for proofer rooms is 316L stainless duct, fully sealed, with closed-cell external insulation to prevent surface condensation. Proofer return ducts run at saturation conditions and need particular attention to drainage points — a sloped duct with a drain trap at the low point prevents condensate accumulation.
Customer-facing bakery display
The customer-facing bakery counter — bread baskets, glass-fronted pastry display, sometimes a coffee station — runs at customer comfort temperature and humidity. The duct work here is general HVAC galvanised G90 with appropriate diffusers. The interface with the production bakery behind is through a swing door or wash-up corridor — the HVAC pressure relationship typically holds the production bakery slightly negative to the customer-facing display, which keeps flour dust and proofer humidity from migrating forward into the customer zone.
Butchery HVAC — chilled prep, food-grade stainless, separate exhaust
The butchery prep room is the highest-grade food-contact zone in the supermarket. Raw meat handling at 4 to 8 degrees Celsius, cleaning with chlorinated wash-down water at the end of every shift, blood and protein residues, and an extended fixture inventory of saws, mincers, slicers and packaging equipment. The HVAC requirements layer on top of refrigeration and food safety.
Chilled prep room temperature control
The prep room target is 4 to 8 degrees Celsius dry bulb, with humidity control to prevent condensation on cold surfaces. Supply air arrives via ducted ceiling diffusers at low velocity to avoid disturbing exposed product on the prep tables. The cooling load is dominated by lighting, equipment and a heavy door-opening cycle as carcasses or primal cuts move in from refrigerated storage and packaged product moves out to the customer-facing display.
Stainless duct construction
The duct material is 304L stainless throughout — both supply and return. The wash-down environment, the chlorinated chemistries used for cleaning, and the requirement for cleanability under AS 4674 Section 3 all push to stainless. 304L specifically (low-carbon variant) avoids sensitisation at welds, which is important for any seam welding the duct contractor does. Duct surfaces inside the prep room are smooth, without internal stiffeners or pockets where contaminant can accumulate. Internal insulation is prohibited — all insulation is external.
Separate exhaust streams
The prep room runs a dedicated exhaust system separate from any other duct system in the store. The exhaust handles odour, residual humidity from wash-down and any aerosols generated by saw operation. Exhaust fans run continuous during prep hours and reduced rate during cleaning. Make-up air is supplied ducted and tempered.
Pressure relationship
The butchery prep room runs slightly negative to the customer-facing meat counter to prevent any odour or aerosol migration forward. The pressure differential is typically 5 to 10 Pascal, controlled by balanced supply and exhaust airflows. The duct contractor's commissioning checklist includes a pressure verification at handover.
Deli, hot food and sushi HVAC
The deli counter, the hot-food bar and the sushi prep zone each have specific HVAC needs that sit between general retail and dedicated food-prep stainless duct.
Deli counter HVAC
The chilled deli display runs as a refrigerated cabinet — its own refrigeration circuit, its own air-curtain physics. The HVAC duct work behind the deli counter handles staff comfort, residual heat from the slicer and any rotisserie or hot-holding equipment. Stainless duct is specified for the prep zone behind the counter where direct food handling happens. Galvanised duct is acceptable for the customer-facing aisle in front of the counter.
Hot-food bar HVAC
The hot-food bar — roast chicken bain-maries, hot pies, soup tureens, hot Asian dishes — runs hot-holding cabinets at 65 degrees Celsius or above. The HVAC duct above the hot-food bar handles steam and hot air rising from the cabinets, and any cooking equipment behind the bar (a small back-of-house kitchen, a rotisserie). Type I or Type II hoods cover the cooking equipment depending on grease loading. Stainless duct in the immediate zone, galvanised duct beyond.
Sushi prep HVAC
Sushi prep is a low-temperature, low-humidity, ultra-clean food-prep zone. Target conditions are 12 to 18 degrees Celsius dry bulb at 50 to 60 percent relative humidity. The duct work is 304L stainless to handle the wash-down environment and the general cleanability requirements. Sushi prep often shares HVAC with other Asian-style fresh-prep zones (poke bowls, salad bars) under a single stainless-duct cluster.
Cafe and food-court HVAC inside the supermarket
Many full-line supermarkets now include a cafe — barista coffee, fresh-prep sandwiches, cake display, sometimes hot dishes. Some Costco and larger Coles or Woolworths sites include a small food court with multiple operators. The HVAC duct package handles two distinct loads.
Kitchen exhaust under NFPA 96
Any cooking that generates grease vapour — pan-frying, deep-frying, char-grill, wok burners — requires a Type I hood with NFPA 96 grease duct. Black steel Schedule 10 welded liquid-tight construction, minimum slope to a collection point, cleanout doors at every change of direction, fire-rated enclosure where the duct passes through occupied space. This duct work is typically beyond the scope of standard SBAL-V auto duct line fabrication and is sourced from specialist welded grease duct shops.
Customer dining HVAC
The customer dining area runs at neutral comfort temperature — 22 to 24 degrees Celsius — with elevated ventilation rate to handle food odours. AS 1668.2 prescribes higher outdoor air for food courts than for general retail. Galvanised G90 supply mains with ceiling diffusers, return through ceiling grilles, demand-controlled ventilation if the zone is large enough to justify the controls. The interface with the kitchen exhaust is a transfer-air or make-up-air arrangement engineered to prevent the kitchen running deeply negative against the dining zone.
Bottle shop and liquor-store HVAC
Liquor retail in Australia covers Dan Murphy's (Woolworths Group), BWS, Liquorland (Coles Group), First Choice and Vintage Cellars. The HVAC duct package is straightforward — galvanised retail HVAC — but two specialised zones merit attention.
Wine cellaring
Premium wine retail (Vintage Cellars, premium sections of Dan Murphy's and First Choice) runs a temperature and humidity-controlled cellar zone for bottle wine. Target conditions are 12 to 14 degrees Celsius dry bulb at 60 to 70 percent relative humidity. The duct work is general galvanised but the zone control is precise — VAV with re-heat to manage overcooling, humidification in winter to prevent cork drying.
Spirits and beer
Spirits and packaged beer have lower priority cooling — ambient-or-cooler is acceptable. The walk-in beer cool room is a refrigerated zone with conventional refrigeration, not HVAC. The customer-facing aisles run at general retail comfort.
Petrol-station and convenience HVAC
The petrol-station convenience format compresses chilled drinks, hot food, coffee and customer comfort into 100 to 300 square metres. The HVAC duct package is small but has high integration complexity. Chilled-drinks cabinets along one or two walls. A coffee station with coffee machine extraction. A hot-food cabinet or pizza oven with NFPA 96 grease duct if the cooking loading justifies. Customer-facing aisles at neutral comfort. Back-of-house storage and cleaner's room.
The duct material spec is mostly galvanised G90 for everything except the food-prep zone behind the counter where stainless 304L is specified for any wash-down or food-contact zone. Spiral round duct in 200 to 400 millimetre diameter handles much of the supply distribution because it suits the small ceiling void space common in convenience tenancies.
Australian sustainability programmes — NABERS, Green Star, GreenPower, refrigerant transition
Supermarket and grocery operators in Australia operate under more sustainability oversight than almost any other retail category. The market signal of ESG performance flows through to capital allocation, financing terms and customer brand. HVAC ductwork sits inside that programme.
NABERS Energy for retail
NABERS — the National Australian Built Environment Rating System — is the primary government-backed performance rating for commercial buildings. NABERS Energy ratings exist for shopping centres and are expanding into supermarkets. A high NABERS Energy rating signals operational efficiency and lower carbon. For HVAC duct design, the implications are tighter duct leakage classes (Class C as default, Class B for premium projects), insulation thickness above NCC Section J minimum, demand-controlled ventilation tied to in-store CO2 sensors, heat recovery from kitchen and refrigeration exhaust, and variable-air-volume control on AHUs to match actual load.
Green Star Performance
Green Star Performance is the Green Building Council of Australia's operational rating tool. New supermarket construction increasingly targets Green Star Design and As-Built ratings, with the Performance rating as the in-use measurement. The HVAC requirements include life-cycle assessment of duct materials, recycled-content steel sourcing, responsible-sourcing certification, and indoor environment quality verification.
GreenPower and renewable electricity
Both Woolworths and Coles run public commitments to 100 percent renewable electricity by 2025 with rooftop PV, on-site batteries and PPAs (power purchase agreements). The HVAC duct work itself is unaffected by the electricity sourcing, but the rooftop equipment layout has to accommodate large PV arrays alongside AHUs, gas coolers and exhaust fans. Roof penetrations need to be coordinated early to avoid PV-array conflicts.
Refrigerant transition — HFC phase-down to HFO and natural refrigerants
Australia is signed up to the Kigali Amendment and is phasing down HFC consumption on a published schedule. New retail refrigeration installations are moving to HFO blends (low-GWP synthetic) or natural refrigerants (CO2, ammonia, propane). The HVAC duct implications are second-order but real — heat-recovery economics improve sharply with CO2 transcritical, rooftop equipment layouts shift, and ventilation requirements may change in plant rooms handling A2L (mildly flammable) HFO refrigerants.
The CO2 transcritical transition — Coles, Woolworths and the implications for HVAC
Coles has publicly committed to 100 percent CO2 transcritical refrigeration across its store network by 2030. Woolworths Group has set similar targets under its sustainability framework. The transition is the largest refrigeration technology shift in Australian supermarket history.
Why CO2 transcritical
CO2 (R-744) has a Global Warming Potential of 1, compared with 1,300 to 4,000 for the HFC refrigerants (R-404A, R-134a, R-407A, R-407F) it replaces. CO2 is non-flammable, non-toxic at supermarket charge volumes, and naturally available without the regulatory constraints of HFCs. Modern transcritical cycle designs with parallel compression, ejector technology and adiabatic gas cooler enhancement have closed the historical efficiency gap with HFC systems and now match or beat HFC efficiency in cool and temperate climates. Australia's southern states (Victoria, NSW, Tasmania, southern WA) are excellent CO2 transcritical climates. Northern tropical climates (Darwin, Cairns) need adiabatic gas cooler enhancement to maintain efficiency at high ambient temperatures.
HVAC duct implications
The standard CO2 transcritical supermarket has a heat-recovery loop from the gas cooler outlet (90 to 110 degrees Celsius) and from a desuperheater intermediate position into a glycol intermediate loop, then via a coil into the AHU heating circuit and the domestic hot water tank. The duct contractor's scope on a CO2 retrofit includes the heating coil mount in the AHU, ductwork modifications around the AHU to accommodate the coil, access doors for cleaning and a bypass damper for non-heating periods. On a new build, this is integrated from day one. On a retrofit, the duct contractor is working in a live store with overnight shutdown windows.
Retrofit project sequencing
A typical Coles or Woolworths CO2 retrofit takes 4 to 8 weeks per store and runs as an overlay project — refrigeration replacement, HVAC re-balancing and electrical upgrades on the same shutdown window. The duct contractor's role is bounded but time-critical. Heat-recovery branches are pre-fabricated off-site, shipped in pre-insulated, and installed during the overnight closure windows. Galvanised G90 is the standard material for the heat-recovery duct.
Construction phasing — shell-and-core then fitout
Most Australian supermarket builds run a shell-and-core delivery from the developer (typically Westfield, Vicinity, Charter Hall, or a private developer for standalone sites) followed by tenant fitout. The fitout is where refrigeration, HVAC, electrical and finishes overlap on a tight programme.
Shell-and-core scope
Shell-and-core typically delivers the structural frame, roof, external walls, base building electrical infrastructure, base building fire services, and base building HVAC for any common areas. Inside the supermarket tenancy, the shell is empty — concrete slab, exposed roof structure, no internal walls, no refrigeration, no fitout HVAC.
Fitout sequence
The standard fitout sequence runs structural penetrations and roof openings first, then in parallel the refrigeration pipework, HVAC ductwork, electrical containment and fire services. Joinery, refrigerated cabinets and shelving follow. Finishes (flooring, paint, signage) close the sequence. Commissioning runs in the final two weeks before opening.
HVAC duct installation timing
HVAC duct installation typically starts week 2 or 3 of the fitout — after structural penetrations are complete, before refrigeration pipework congests the ceiling. The duct contractor delivers prefabricated mains and branches in batches, hangs to the structure, fits insulation, and pressure-tests on completion. Coordination with refrigeration is critical — refrigeration pipe runs and HVAC duct runs share ceiling space and the order of installation matters for access.
Programme stress points
The two reliable programme stress points on a supermarket fitout are coil supply (galvanised and stainless) and skilled labour availability. A 5,000-square-metre Woolworths or Coles fitout consumes 8,000 to 14,000 kilograms of galvanised plus 800 to 1,500 kilograms of stainless — that is roughly 25 to 50 coils. Coil supply tightens cyclically and a contractor without forward-stocked material can lose two weeks. Skilled sheet-metal labour is in chronic short supply across Australia and the contractors who run their own SBKJ-equipped fabrication shops have a programme advantage over those who buy fittings from a distributor.
Supermarket retrofit market — 1990s and 2000s stores
Australia has a large fleet of 1990s and 2000s supermarkets running HFC refrigeration, low-efficiency HVAC, no heat recovery and ageing ductwork. The retrofit market for these stores is large and growing, driven by HFC phase-down compliance, NABERS Energy targets and operator commitments to natural refrigerants.
Typical retrofit scope
A standard supermarket retrofit replaces the refrigeration system (HFC to CO2 transcritical or HFO blend), upgrades the HVAC to add heat recovery and demand-controlled ventilation, replaces refrigerated cabinets with current-generation low-energy designs, and modernises the controls system. Lighting upgrades to LED are usually bundled. The HVAC duct scope is partial — the existing mains may be retained if leakage tests pass, branches near new equipment are replaced, heat-recovery branches are added.
Working in a live store
Supermarket retrofits run with the store trading. Work happens overnight (typically 11pm to 5am) with everything dismantled and the store cleaned for the morning trade. Duct work has to be prefabricated off-site, delivered in shifts, hung and connected in the overnight window, and the ceiling closed back up before opening. The contractor needs a fast prefab capability — an SBAL-V auto duct line and a TDF flange former running second shift — and a logistics plan that gets the right ducts to the right trade window.
Programme economics
A typical Coles or Woolworths CO2 retrofit costs in the order of AUD 800,000 to 1,500,000 per store across all trades. The HVAC duct portion is 10 to 18 percent of the total. The economics are driven by refrigeration energy savings (15 to 25 percent reduction typical) plus the avoided HFC compliance cost as the phase-down accelerates.
Materials specification — galvanised, stainless, black steel
The supermarket HVAC duct material specification is a function of zone — every zone has a default material and a few zones have specific upgrade requirements. The duct contractor's bill of materials reflects the zoning.
Galvanised G90 sheet steel
The default material for general HVAC supply, return, transfer and exhaust runs in dry grocery, customer comfort, back-of-house storage, plant areas and any zone where the duct does not touch food preparation directly. G90 specifies 90 g/m² zinc coating per side (total 180 g/m² for both sides) which gives 20-plus year service life in indoor HVAC application. Sheet thickness ranges from 0.6 to 1.2 millimetres depending on duct size and pressure class. Standard SBAL-V auto duct line tooling handles galvanised across this thickness range.
304L stainless steel
Specified for food-contact and food-preparation zones — butchery prep, deli prep, sushi prep, fresh seafood, cafe back-of-house if direct food handling. The L (low carbon) variant resists carbide precipitation at welds, which matters for any seam welding the duct contractor performs. Sheet thickness is similar to galvanised — 0.6 to 1.2 millimetres. The SBAL-V auto duct line can run 304L with tooling adjustment but second-shift segregation from galvanised production is recommended to prevent cross-contamination of the stainless surface with galvanised dust.
316L stainless steel
Specified for high-humidity zones where 304L would pit over time — bakery proofing rooms running 60 to 80 percent RH, fresh-fish wash-down zones with chlorinated water, and any duct exposed to extended high-humidity service. Sheet thickness as 304L. 316L includes molybdenum which resists chloride pitting.
Black steel Schedule 10 welded
The exclusive material for NFPA 96 commercial cooking grease ducts. Schedule 10 is the standard wall thickness, fully welded liquid-tight construction, sloped to a collection point, with cleanout doors at every change of direction and a fire-rated enclosure where the duct passes through occupied space. This duct work is typically beyond the scope of standard SBAL-V auto duct line fabrication and is sourced from specialist welded grease duct shops who have certified welders and a dedicated welding bay.
Specialist materials
Aluminium and aluminium-zinc-alloy coated steels are sometimes specified for very high humidity or saline-air exposure. PVC-coated galvanised is used for some chemical-fume exhausts but rarely in supermarket service. Phenolic-foam pre-insulated panel duct is occasionally specified for chilled-supply runs in retrofit projects where minimum thickness is critical.
SBKJ machinery for supermarket projects
The standard SBKJ machinery kit for an HVAC contractor servicing the Australian supermarket market is built around three core machines plus a few support tools. The kit handles the galvanised general HVAC, the stainless food-zone fabrication, the round duct distribution and the flange-and-cleat connections.
SBAL-V auto duct line for galvanised rectangular HVAC
The SBAL-V auto duct line is the workhorse for general supermarket HVAC. It takes coil stock, levels, slits, cuts, notches, brakes, beads and forms rectangular duct in a single integrated pass. Single-shift output for an experienced operator runs 250 to 400 metres per shift on standard galvanised 0.6 to 1.0 millimetre. A 5,000-square-metre Woolworths or Coles fitout consuming 8,000 to 14,000 kilograms of galvanised completes its prefabrication in 4 to 6 weeks single-shift on a properly tooled SBAL-V. With two SBAL-V lines or one running double shift, the same package compresses to 2 to 3 weeks.
SBAL-V configured for stainless food-zone duct
The same SBAL-V platform runs 304L and 316L stainless coil with adjusted tooling — feed rollers, brake dies and the bead roller are stainless-rated. Stainless surface protection during forming requires film coating on the coil and clean tooling. SBKJ recommends second-shift stainless production segregated from galvanised to prevent cross-contamination. The 800 to 1,500 kilograms of stainless on a typical full-line supermarket fabricates in 3 to 5 days on a stainless-configured SBAL-V.
SBTF spiral tubeformer for round duct
The SBTF spiral tubeformer handles round duct distribution. Round duct features heavily in supermarket HVAC for plant-room connections, customer-zone supply trunks where ceiling height and aesthetic permit, and back-of-house exhaust. Spiral round duct takes static at lower gauge weight than rectangular, which suits the long supply runs in larger formats (Costco, Bunnings). Diameter range 100 to 1,500 millimetres covers all common supermarket sizes. Output runs 100 to 200 metres per shift depending on diameter.
TDF flange former for tight pressure-class connections
The TDF (Transverse Duct Flange) flange former rolls a continuous flange directly onto the duct end, creating a proprietary flange profile that mates to the adjacent duct with a gasket and corner cleats. TDF flanges achieve tight leakage performance — Class C is straightforward and Class B is achievable with care on assembly. For NABERS-aligned and energy-efficient projects, TDF flanges are essentially mandatory. The TDF flange former is integrated into the SBAL-V line on most installations and runs in-line with no additional handling.
Plasma cutters and shears for fittings work
Supermarket HVAC includes a high proportion of fittings — elbows, branches, transitions, end caps, access doors. The duct contractor's shop typically runs a plasma cutter, a sheet shear and a folding brake to fabricate fittings from cut blanks. SBKJ supplies these support machines as part of the integrated kit.
What is outside SBKJ scope
Welded grease duct fabrication for NFPA 96 commercial cooking exhaust is outside the standard SBKJ machine scope. Liquid-tight welded construction with all-position welder qualification and dedicated welding bays is a specialist trade — most HVAC duct contractors source welded grease duct from specialist welded duct shops. SBKJ's recommendation to supermarket-focused contractors is to build the galvanised-and-stainless capability in-house with an SBAL-V kit and outsource the welded grease duct.
Get an SBKJ supermarket-fabrication kit specification →
FAQ — supermarket and grocery HVAC ductwork
Why is supermarket HVAC ductwork different from office or warehouse ductwork?
A supermarket runs eight to twelve thermally distinct zones under one roof — chilled produce, frozen, dairy and deli, dry grocery, bakery, hot food, customer comfort, back-of-house. The HVAC has to deliver each setpoint without disturbing the cold curtains spilling from open multideck refrigerated cabinets, capture grease and steam from cooking zones under NFPA 96, and recover heat from refrigeration condensers for store heating and hot water. Energy intensity for a typical Australian supermarket runs 1,000 to 2,500 kWh per square metre per year — five to eight times an office of the same area.
What ductwork material should be specified for supermarket food-contact zones?
Galvanised G90 for general HVAC in dry grocery, customer comfort and back-of-house storage. 304L stainless steel for butchery, deli, sushi and fresh-seafood prep zones governed by AS 4674 Section 3. 316L stainless for high-humidity zones such as bakery proofing rooms. Black steel Schedule 10 welded for NFPA 96 commercial cooking grease ducts — typically beyond the scope of standard duct line forming and outsourced to welded duct specialists.
How does HVAC interact with open refrigerated multideck cabinets?
An open multideck cabinet produces a thin curtain of cold air falling from top discharge to bottom return. Any HVAC supply jet hitting the cabinet face at more than around 0.25 metres per second velocity disrupts the curtain, dumps cold air into the aisle and increases cabinet refrigeration energy by 15 to 30 percent. Mitigation is low-velocity supply diffusers (face velocity below 0.5 m/s), displacement ventilation in produce zones, and dedicated outdoor air systems decoupling fresh-air ventilation from sensible cooling.
What Australian standards govern supermarket HVAC ductwork?
AS 1668.2 sets minimum mechanical ventilation rates. AS 4674 covers food premises ventilation, surface materials and cleanability. AS 1530.4 governs fire-resistance testing for fire-rated ducts. AS/NZS 4254 Parts 1 and 2 are the duct construction standards. Imported references include ASHRAE 62.1 (IAQ ventilation), ASHRAE 90.1 (energy), NFPA 96 (commercial cooking exhaust) and the FSANZ Food Standards Code Chapter 3.
How long does HVAC ductwork fabrication take for a typical Australian supermarket fitout?
A 3,500 to 5,000 square metre full-line supermarket runs 8,000 to 14,000 kg galvanised plus 800 to 1,500 kg stainless. Fabrication on a properly tooled SBAL-V auto duct line plus a TDF flange former runs 4 to 6 weeks single-shift. Total fitout from shell handover to opening day is typically 10 to 14 weeks. ALDI's compact format compresses to 6 to 9 weeks total. Convenience and 7-Eleven sites finish in 3 to 5 weeks.
What is CO2 transcritical refrigeration and why are Coles and Woolworths transitioning?
CO2 transcritical uses CO2 (R-744) as refrigerant with GWP of 1 versus 1,300 to 4,000 for the HFCs it replaces. Coles has committed to 100 percent CO2 transcritical by 2030, Woolworths Group has similar targets. CO2 systems reject heat at higher temperatures, making heat recovery into store heating and hot water far more efficient. HVAC implications include heat-recovery ductwork from gas coolers into AHU coils.
What is NABERS Energy and how does it affect HVAC duct design?
NABERS — National Australian Built Environment Rating System — runs an energy rating tool for shopping centres and is expanding into supermarkets. For HVAC ductwork the implications are tighter duct leakage classes (target Class C or B per AS/NZS 4254), insulation thickness above NCC Section J minimums, demand-controlled ventilation tied to CO2 sensors, heat recovery from kitchen and refrigeration exhaust, and variable-air-volume control on AHUs.
Can SBKJ machinery fabricate ductwork for a supermarket fitout?
Yes. The standard kit is an SBAL-V auto duct line for galvanised rectangular HVAC, an SBTF spiral tubeformer for round duct, and a TDF flange former for tight pressure-class connections. The same SBAL-V runs 304L and 316L stainless for food-contact zones with adjusted tooling. Welded grease-duct fabrication for NFPA 96 commercial cooking exhaust is outside standard SBKJ scope and is sourced from specialist welded duct shops.
