Why airport HVAC is unique
An international passenger terminal is a small city under one roof. A typical Tier 1 terminal of 200,000–400,000 m² floor area handles between 15 and 60 million passengers per year, runs continuously for 365 days, and combines retail, dining, security screening, immigration, customs, transit lounges, gate hold rooms, baggage handling, airline offices, government agencies, plant rooms and back-of-house circulation in a single building envelope. The HVAC system serving this envelope handles peak occupant loads of more than 8,000 people per hour at major hub gates, while simultaneously maintaining tight pressure relationships across security boundaries, smoke management readiness across 50,000+ m² of contiguous floor plate, and indoor air quality that meets or exceeds passenger expectations after a 14-hour international flight.
Airports are also among the most energy-intensive public buildings constructed today. A single Tier 1 terminal can consume 200–400 GWh per year of electrical energy, with HVAC accounting for 45–60% of that total. The drive for ASHRAE 90.1 and NCC Section J compliance, combined with operator pressure on operating costs and decarbonisation commitments, has pushed terminal HVAC design toward demand-controlled ventilation, economiser cycles, free cooling overnight, displacement ventilation in tall volumes, and tight integration with terminal-wide building management systems. None of this works without ductwork that meets the leakage, pressure and fire-rating specifications the design intent assumes.
This guide is the field-engineering perspective on what makes airport HVAC ductwork different from any other commercial building, what the codes actually require, what materials and construction details work in practice, where the specification typically goes wrong, and how the duct fabrication subcontractor — the supplier almost no airport master plan names — fits into the procurement chain. SBKJ Group has supplied auto duct lines, spiral tubeformers and TDF flange formers to fabricators serving airport projects in 60+ countries, and the patterns are remarkably consistent.
The airport facility map
Before any HVAC engineer can size a duct, they need to map the facility against the eight broad zones an airport typically contains. Each zone has a different code reference, occupancy profile, pressure relationship and material specification. Treating the entire airport as a single HVAC problem is the largest design error we see on first-time aviation projects.
Passenger terminal
The passenger terminal is what most people think of when they hear "airport HVAC", and within the terminal envelope there are at least seven distinct sub-zones with different ventilation requirements. The departures level typically runs 7.5 L/s per person plus 0.3 L/s/m² per ASHRAE 62.1, with peak occupant density driving demand-controlled ventilation cycles tied to flight schedule and check-in counter occupancy sensors. The arrivals level has a similar profile but with concentrated peaks around immigration and baggage reclaim. The transit and airside concourse runs almost continuous occupancy with retail and food court contributions to the ventilation rate. Gate hold rooms swing from near-empty to standing-room-only on a 30-minute cycle as flights board, which is why displacement ventilation and high-output gate diffusers have largely replaced overhead mixing systems in modern terminals.
Premium and airline lounges typically run their own dedicated AHU branch with tighter humidity control, lower noise targets (NC 30 or below), and higher fresh air per occupant. Retail tenancies are usually served by either a base-build VAV branch with tenant secondary heating and cooling, or a dedicated fan coil unit per tenancy with chilled water and condenser water reticulation from the base building.
Airside operations
Airside means everything past the security boundary toward the apron. This includes the gate area HVAC mentioned above, the jet bridges (also called aerobridges) that connect the gate hold room to the aircraft door, the baggage handling system makeup air and exhaust, ground services equipment workshops, and any apron-facing lounges or observation decks. Jet bridges are HVAC microcosms in themselves — covered later in this guide — and the baggage handling hall is a high-ceiling, sparse-occupant zone that runs primarily on AS 1668.2 or ASHRAE 62.1 area-based ventilation (0.6 L/s/m²) with localised exhaust at the X-ray and screening positions.
Groundside operations
Groundside is the public-access side: kerbside pickup and dropoff, taxi and bus ranks, multi-storey carparks, ground transport interchanges and rail station integration. Carparks are governed by carbon monoxide-driven jet fan systems rather than conventional ducted ventilation, but the ground transport interchange and rail platform ventilation typically use large-section galvanised duct for tunnel ventilation and smoke management.
MRO hangars
Maintenance, Repair and Overhaul (MRO) hangars are massive single-volume spaces — typical wide-body MRO hangars at 80,000–150,000 m³ envelope volume — with very different HVAC profiles to passenger buildings. NFPA 410 governs aircraft maintenance, NFPA 415 governs aircraft fueling, and the duct system must accommodate hangar door operations, paint booth integration if present, dedicated jet fuel exhaust, and explosion-proof zone classification anywhere fueling or open-bay paint operations occur.
Air Traffic Control tower
The ATC tower is a small but extremely high-criticality facility. The cab — the glazed space where controllers work — must maintain tight 20–22°C and 45–55% RH year-round to protect radar displays, communications equipment and controller comfort over 8–12 hour shifts. The equipment rooms below the cab house the radar and comms gear with their own redundant cooling. Two physically separate AHUs with N+1 redundancy on chillers, fans and humidifiers, supplied through dual independent ductwork risers, is the standard architecture for any ATC tower above the "remote" or "low traffic" classification under ICAO Annex 14.
Fire station and emergency response
Airport fire stations house Aircraft Rescue and Fire Fighting (ARFF) vehicles and crew. The vehicle bay requires high-rate exhaust ventilation when engines are running, ducted directly above each bay, with explosion-proof fans rated for diesel exhaust. The crew quarters operate as a normal commercial HVAC zone but with shift sleeping rooms requiring tighter acoustic and humidity control.
Fuel farm
The fuel farm is where Jet A-1 is stored and pumped into the underground hydrant system. NFPA 415 and ATEX/IECEx zone classification govern the ventilation and electrical specification of any enclosed fuel pump room, valve manifold building or below-grade vault. Ventilation rates run 12 air changes per hour minimum, with explosion-proof fans, leak detection interlocks, and dedicated extract from any low point where vapour can pool.
Cargo terminals
Cargo handling buildings are large-volume sheds with low cooling load most of the time, typically served by VRF or evaporative cooling. The exception is refrigerated cargo zones — pharmaceutical cold chain, fresh produce, perishable food — which require insulated panel construction, dedicated dehumidification AHUs and HEPA H13 filtration where pharmaceutical GDP compliance applies.
Major Australian airport projects
Australia has the largest pipeline of airport infrastructure in three decades. The HVAC ductwork demand from the projects below — combined with state-government rail and convention centre work — has pushed every major Australian duct fabricator to expand capacity, which in turn has driven equipment orders for SBAL-V auto duct lines, SBTF spiral tubeformers and TDF flange formers across the country.
Western Sydney International Airport (Nancy-Bird Walton)
Western Sydney International (WSI), located at Badgerys Creek, is Australia's first new major airport in 50 years, with a USD 5.3 billion construction budget and an opening date of late 2026. The single passenger terminal is approximately 79,000 m² at opening, designed to scale to multiple terminal modules over the airport's life. The HVAC scope spans landside, airside, the main terminal building, the multi-storey carpark, the rail station, and ancillary buildings including the ATC tower and fire station. The terminal is targeting a 5-Star Green Star rating and substantial NCC Section J compliance, which has driven a design including displacement ventilation in the central atrium, fabric duct in the retail spine, perimeter slot diffusers at the airside glazing, and underfloor air distribution in the airline lounges.
Brisbane Airport — new runway and T1 expansion
Brisbane Airport's parallel runway opened in 2020, but the terminal expansion programme continues through the late 2020s with a major T1 international terminal expansion adding new gates, airline lounges, retail and food court tenancies. The HVAC retrofit and expansion package is a complex live-airport phased construction sequence — most ductwork is installed during overnight closure windows, and the duct fabricator must support short delivery cycles and intricate site coordination.
Melbourne Airport (Tullamarine) T2 international expansion
Melbourne Airport's T2 international terminal expansion, part of the Melbourne Airport Master Plan, adds new gates and processing capacity to support the airport's planned growth toward 70+ million passengers per year. The HVAC scope includes new AHU farms on the roof, expanded smoke extraction risers through the existing structure, fabric duct in the new retail concourse and 316L stainless duct in the new food court. The Melbourne project is also driving development of a third runway, with associated taxiway lighting plant rooms and expanded ATC infrastructure.
Sydney Kingsford Smith T1 international refurbishment
Sydney's T1 international terminal is undergoing a multi-year refurbishment programme covering check-in, security screening, departures concourse, retail, lounges, immigration and baggage reclaim. The challenge — common to every brownfield terminal upgrade — is integrating new ductwork into the existing high-density services zone above the ceiling without compromising passenger throughput during construction. Phased weekend closures, modular AHU swaps, and pre-fabricated ductwork shipped to site in pre-assembled sections are standard practice.
Perth Airport — runway and terminal expansion
Perth Airport's expansion includes a runway upgrade, expansion of T1 international, and consolidation of T3 and T4 domestic operations. The HVAC duct scope spans terminal expansion, jet bridge replacement and the upgraded ATC and ARFF facilities supporting the new runway.
Hobart Airport runway extension
Hobart Airport's runway extension supports direct international and Antarctic gateway flights. The terminal expansion adds international processing, a small lounge and retail footprint, and an upgraded ATC and ARFF tower. Smaller in scale than the Tier 1 mainland projects but with the same code stack and HVAC architecture.
Adelaide Airport T1 expansion
Adelaide Airport's T1 expansion adds new gates and processing capacity, with HVAC scope across the new airside concourse, upgraded baggage handling and a refurbished landside arrivals hall.
Major global airport projects
Outside Australia, the next decade of major airport HVAC ductwork demand sits in a handful of mega-projects. The duct fabrication subcontractor for each of these is typically a regional or local company running modern automatic duct lines and spiral tubeformers, with SBKJ machinery represented in many of these workshops.
Riyadh King Salman International Airport
Saudi Arabia's King Salman International Airport (KSIA) is targeted to handle 120 million passengers per year by 2030, expanding to 185 million by 2050, with six parallel runways and a footprint of approximately 57 km². The terminal complex is one of the largest single airport HVAC projects ever attempted, with duct linear-metre quantities running into the millions. Fabricator workshops in the Riyadh and Dammam region are scaling up auto duct line capacity to meet the schedule.
Dubai Al Maktoum (DWC) expansion
Al Maktoum International, the planned successor to Dubai International (DXB), is being scaled to a target capacity of 260 million passengers per year, making it the largest airport in the world by capacity. The terminal complex, concourses, MRO facilities and cargo zones together represent a multi-decade HVAC ductwork pipeline.
Abu Dhabi T-A (Midfield Terminal)
Abu Dhabi's Terminal A (formerly Midfield Terminal) opened in late 2024 and continues phased fitout completion. The terminal includes a 200,000+ m² floor plate, large central atrium with displacement ventilation, and extensive smoke extraction infrastructure designed to NFPA 92.
Istanbul New Airport (IGA) Phase 2
Istanbul New Airport is progressing through additional terminal modules and the planned T2 expansion, scaling toward an ultimate capacity of 200 million passengers per year. The HVAC scope continues to drive duct fabrication demand across Turkey and the surrounding region.
Singapore Changi T5
Changi Airport's Terminal 5 (T5) is one of the most technically advanced terminal projects under design globally, targeting 50 million passengers per year capacity with passive design, displacement ventilation and integrated landscape cooling driving the HVAC strategy.
Hong Kong International Airport T2 concourse expansion
Hong Kong International Airport's T2 concourse expansion and three-runway system together drive substantial HVAC scope across both new and refurbished terminal spaces.
Mumbai T3 expansion and Navi Mumbai International Airport
Mumbai's existing T3 terminal expansion combined with the new Navi Mumbai International Airport at Panvel together represent the largest Indian airport HVAC pipeline of the decade.
Manila NAIA upgrade and New Manila International Airport
The Ninoy Aquino International Airport (NAIA) upgrade and the planned New Manila International Airport (Bulacan) drive continuing Philippine airport HVAC demand.
Key codes and standards
Airport HVAC sits at the intersection of building services codes, fire and life safety codes, aviation regulations and energy codes. The exact code stack depends on jurisdiction, but the patterns below are typical for any major international airport project.
ASHRAE 62.1 — ventilation for acceptable indoor air quality
ASHRAE 62.1-2022 Table 6-1 sets the minimum outdoor air rate per occupancy. For airport spaces specifically: airport baggage areas 7.5 L/s per person plus 0.6 L/s/m², airport concourses 7.5 L/s/person plus 0.3 L/s/m², waiting areas 3.8 L/s/person plus 0.3 L/s/m², gate area lounge 3.8 L/s/person plus 0.3 L/s/m², and lobbies 3.8 L/s/person plus 0.3 L/s/m². Retail tenancies, restaurants, kitchens, restrooms and back-of-house areas follow their own table entries. The standard's ventilation-rate procedure is the default; the IAQ procedure is rare on airport projects because of the expense of CO₂ and VOC monitoring across the building.
ASHRAE 90.1 — energy
ASHRAE 90.1-2022 sets the energy efficiency baseline for HVAC systems including duct leakage class, fan power limits, economiser requirements and demand-controlled ventilation triggers. Most airport projects target 90.1 Section 6 compliance via the prescriptive path with a mandatory leakage class of C or tighter on supply ductwork — equivalent to less than 0.014 L/s/m²/Pa^0.65.
ASHRAE 170 — health care facilities
ASHRAE 170 applies where the airport contains a medical clinic, first aid station, vaccination centre or pharmacy. The standard sets airflow patterns, pressure relationships and filtration grades for clinical spaces and is invoked by reference in most airport master plans for the first aid station HVAC scope.
NFPA 92 — smoke management
NFPA 92 governs smoke management in atria, large compartments and any enclosed space where smoke layer interface management is required for egress. For an airport atrium, NFPA 92 requires the smoke layer to remain at least 1.8 m above the highest occupant level for the design fire duration. Smoke exhaust rates run 200–500 m³/s for typical airport atria, with EI 60 or EI 120 fire-rated duct on smoke risers.
NFPA 410 — aircraft maintenance
NFPA 410 governs aircraft maintenance hangar HVAC, including fire protection, ventilation rates and explosion-proof requirements where fueling or paint operations occur.
NFPA 415 — aircraft fueling
NFPA 415 governs aircraft fueling ramp drainage, ventilation and explosion-proof equipment for any space where Jet A-1 is handled. Fuel farm pump rooms, valve manifold buildings, below-grade vaults and any apron-edge fueling control buildings fall under NFPA 415.
ICAO Annex 14 — aerodromes
ICAO Annex 14 is the international standard for aerodrome design and operation. While not primarily an HVAC document, it sets the architectural and operational context for the ATC tower, the runway and taxiway lighting plant rooms, and the apron and stand layout that drives jet bridge HVAC scope.
FAA Advisory Circular AC 150 series
The FAA AC 150 series provides design guidance for US airports and is widely referenced internationally. AC 150/5300-13 covers airport design generally, AC 150/5210 covers ARFF, and AC 150/5345 covers airport visual aids — all of which influence the supporting facilities HVAC scope.
Australian-specific codes
Australian airport projects layer the international stack on top of Australian standards: AS 1668.2 sets mechanical ventilation rates and is the equivalent of ASHRAE 62.1 for AS-jurisdiction projects. Section 4 of AS 1668.2 covers air-quantity calculations including the minimum makeup air for kitchens, the per-person plus per-area outdoor air calculation for occupied spaces, and the contaminant-source extract rates for bathrooms and back-of-house. NCC Section J sets energy efficiency requirements in the National Construction Code and is the energy-code equivalent of ASHRAE 90.1. AS 4254.2 governs HVAC duct construction including pressure class, leakage class and fire performance. AS/NZS 3000 sets electrical wiring standards including hazardous area zoning. CASA airworthiness regulations apply to any HVAC installation that interacts with aircraft directly — most relevant in MRO hangars and on jet bridges.
Terminal HVAC architecture
The terminal HVAC architecture described below is the consensus model across the major Tier 1 airport projects of the past decade. Variations exist for climate zone, owner preference and architectural geometry, but the building blocks are remarkably consistent.
High-volume air handling unit farms
Modern terminals consolidate AHUs into "farms" on the roof or in dedicated plant decks, with each farm typically serving 20,000–40,000 m² of floor plate. Each AHU is sized at 30,000–80,000 L/s supply airflow, with full economiser cycle, return fan, low-leakage damper assemblies and MERV 13 minimum filtration. The farm architecture allows individual AHUs to be taken offline for maintenance without losing the entire concourse, and supports staged operation through the day where overnight shoulder hours need only 30–40% of the daytime capacity.
Fabric duct in retail and atria
Fabric duct (permeable textile duct, brand examples include Durkeesox, KE Fibertec and Prihoda) has become the default supply distribution in retail concourses, food courts and tall atria. The advantages over rigid duct are: low installed weight (helpful for long-span structural ceilings), fast installation, low condensation risk because the entire fabric surface is at supply air temperature, even air discharge along the full duct length, and visual finish that integrates with the architectural intent. Fabric duct does not replace rigid ductwork upstream — supply trunks are still galvanised rectangular — but the final distribution to the occupied zone uses fabric.
Displacement ventilation in atria
Tall atrium volumes — 15 m and above — benefit from displacement ventilation rather than overhead mixing systems. Cool supply air at 18–20°C is introduced at low level through fabric or perforated metal diffusers, drifts through the occupied zone picking up heat and contaminants, and rises to the upper volume where it is extracted at high level. Displacement systems operate at lower fan power than overhead mixing, support free cooling and economiser cycles more efficiently, and integrate cleanly with smoke management because the smoke layer naturally forms in the upper volume where the exhaust grilles already are.
Perimeter slot diffusers at floor-to-ceiling glazing
Modern terminals have floor-to-ceiling glazing at the airside facade that delivers passenger views of the apron — but creates massive solar gain in summer and downdraft in winter. Continuous perimeter slot diffusers at the floor or low-level perimeter blow conditioned air upward across the glass, neutralising the convective downdraft and counteracting the solar gain. Slot diffuser ducts are typically 0.7–0.9 mm galvanised, run at low pressure class, and connected to a dedicated perimeter VAV box per glazing module.
Underfloor air distribution in offices and lounges
Airline office spaces and premium lounges increasingly use Underfloor Air Distribution (UFAD) where conditioned air is delivered through floor-mounted diffusers from a pressurised plenum below the raised access floor. UFAD supports tighter individual zone control, lower fan static pressure, and direct integration with the cable and data distribution that office and lounge spaces require. The supply duct from the AHU drops into the underfloor plenum through a dedicated supply riser.
Pressure relationships
Pressure mapping across an airport terminal is one of the most under-specified aspects of master-plan-level HVAC documentation. The default approach is: positive in the post-security clean side (departures concourse, gate hold rooms), negative in the immigration and customs sterile zone (so any leaked air drifts inward toward the controlled zone, not outward into the public area), neutral in the curbside, kerbside and groundside circulation, negative in restrooms, kitchens and food court back-of-house, and positive in plant rooms with hot equipment to prevent unwanted infiltration of moisture.
The duct system must hold these pressure relationships under all operating conditions — including economiser changeover, smoke control activation and partial AHU outage. Pressure relationships are typically achieved through differential supply versus return airflow, sized 5–15% above or below balance depending on the target differential. Door undercuts, transfer grilles and dedicated return air paths must all be modelled in the design BIM to confirm the differential holds.
Smoke management — NFPA 92
NFPA 92 smoke management is the most technically demanding aspect of airport HVAC design. The standard requires the design team to calculate the smoke layer interface height under a defined design fire, using either the Heskestad plume equation, axisymmetric plume modelling, or computational fluid dynamics for complex geometries. The smoke layer must remain at least 1.8 m above the highest occupant level for the duration of egress — typically 6–10 minutes for an airport atrium — through a combination of smoke exhaust, makeup air and architectural reservoir geometry.
For a typical 25 m high airport atrium with 50,000 m² floor plate and a design fire of 5 MW, smoke exhaust rates run 200–500 m³/s with main extract risers of 1.6–2.5 m equivalent diameter. The smoke duct itself is typically 1.2–1.5 mm galvanised steel or 304 stainless steel, fabricated with TDF flange joints on a 1,500 Pa pressure class, and fire-rated to EI 60 or EI 120 depending on whether the duct passes through compartmented spaces. Fire dampers at compartment boundaries are coordinated with the BMS so they remain open under smoke control mode but close on fire-mode signal from the affected compartment.
The supply makeup air for smoke control is often overlooked and just as critical as the exhaust. Makeup air is introduced at low level into the smoke control zone at a rate matched to the exhaust, drawn either from outside air through dedicated dampered louvres or transferred from adjacent positively pressurised compartments. Inadequate makeup air collapses the smoke layer interface and defeats the entire NFPA 92 strategy.
Coordination with sprinkler design is mandatory. Sprinklers and smoke management are commonly perceived as alternative strategies, but in atrium fire engineering they are usually combined — sprinklers control fire growth at lower levels, smoke management protects the upper egress paths. Design fire size is reduced when sprinklers are present, but the smoke control system is still required.
Read our fire and smoke damper integration guide →
Air filtration for aviation contamination
Airside-facing AHUs are exposed to contamination sources that landside terminals do not face: jet exhaust, fuel vapour, deicing fluid aerosol in winter, brake dust from heavy aircraft braking, and apron dust kicked up by ground services equipment. The default filtration spec on airside-facing AHUs is therefore higher than the ASHRAE 62.1 minimum of MERV 13. Most airport projects specify MERV 14 or 15 on the supply side of any AHU drawing outdoor air from the airside facade or the apron-edge plant rooms.
Activated carbon adsorption stages are added on AHUs serving sensitive zones — first aid stations, pharmaceutical cargo cold rooms, ATC tower equipment areas — to reduce volatile organic compound and odour penetration from the apron. HEPA H13 filtration is required for medical clinic supply air and pharmaceutical cargo cold rooms operating to GDP standards.
Jet bridge / aerobridge HVAC
The jet bridge — the telescoping passenger loading bridge that connects the terminal gate to the aircraft door — is a small but high-profile HVAC zone. Each bridge is typically served by a dedicated AHU of 3,000–8,000 L/s capacity, mounted at the rotunda (the fixed end at the terminal). The bridge itself is a heavily glazed, narrow tube that experiences extreme solar gain in summer and condensation risk in cold climates because the floor is suspended above the apron with nothing but air beneath.
HVAC duct in a jet bridge runs through the upper structure or below the floor, distributing supply through linear slot diffusers along the length of the bridge. Pressure class 500 Pa minimum on TDF flange joints, 0.7–1.0 mm galvanised rectangular section, with insulation rated for both thermal performance and moisture resistance. Condensation drain pans run beneath the bridge canopy to capture any moisture that penetrates the insulation.
A fire damper at the terminal interface — where the bridge connects back to the gate hold room — is mandatory under most jurisdictions. The damper closes on fire signal from either the bridge or the terminal side, isolating the bridge ventilation from the terminal smoke control system.
Pre-Conditioned Air (PCA) — the chilled or heated air supplied to the docked aircraft cabin while the engines are off — is a separate system from the bridge HVAC. PCA units sit on the apron beneath the bridge, with insulated flexible hose to the aircraft. The PCA control panel is normally on the bridge but the airflow does not enter the human-occupied bridge volume.
Aircraft hangar HVAC
An MRO hangar capable of accepting a wide-body aircraft (Boeing 777, Airbus A330 or larger) is typically 100–120 m wide, 70–90 m deep and 25–35 m high — a single-volume space of 80,000–150,000 m³. The HVAC challenge is fundamentally different from a passenger terminal: massive volume but low continuous occupancy, high-rate ventilation only when fueling or paint operations are active, large hangar door openings that disrupt any conventional ducted system, and explosion-proof zone classification anywhere fueling occurs.
Conventional HVAC for hangar spaces
For maintenance operations not involving fueling, the hangar HVAC is sized to maintain a comfortable working temperature — typically 18–22°C in summer with cooling, 16–20°C in winter with heating. The design air change rate is 2–4 ACH continuously, with high-throw nozzle diffusers from roof-mounted AHUs or floor-mounted air handlers around the perimeter. Ductwork is heavy gauge — 1.2–1.5 mm galvanised — to withstand the abuse of crane operations, scissor lifts and the occasional aircraft towing collision.
Hangar door air curtains
Hangar doors are the largest infiltration source on any aircraft hangar. Door air curtains — high-velocity downward-blowing supply air across the full door opening — reduce conditioned air loss when the door is open. Air curtain ducts are typically 1.2 mm galvanised, sized for high airflow at moderate static pressure, with linear slot discharge across the full door width.
Fueling and paint operations
When fueling is permitted in the hangar, the entire space (or the fueling-specific bay) is reclassified as Zone 2 under IECEx, requiring explosion-proof fans, dedicated jet fuel exhaust at high rates (typically 6–10 ACH local extract from the fueling area), and continuous gas detection interlocked with the ventilation system. NFPA 415 is the governing code in US-influenced markets; AS/NZS 60079 for ATEX/IECEx and AS 1940 for flammable liquid handling apply in Australia.
Paint operations in a paint hangar bay require dedicated paint booth ductwork with explosion-proof fans, particulate filtration to recover overspray, and separation from the rest of the hangar HVAC. The paint booth supply and exhaust ducts are heavy gauge, often coated steel rather than bare galvanised to resist solvent attack.
ATC tower HVAC
The Air Traffic Control tower is one of the highest-criticality HVAC zones on any airport. Loss of the cab HVAC during operating hours is an immediate operational impact — radar displays overheat, controllers fatigue, and the airport may need to reduce operations or transfer control to a backup facility. Redundancy is therefore non-negotiable.
The standard architecture is two physically separate AHUs (typically each sized at 100% of the design load, giving N+1 redundancy), with two independent supply paths through the tower riser. Each AHU has its own chiller line, humidifier, fans on UPS-backed VFDs, and BMS monitoring with automatic changeover on failure. The cab itself runs at tight 20–22°C and 45–55% RH year-round to protect the radar displays and communications equipment, with controller-comfort overrides limited to a narrow setpoint band.
The equipment rooms below the cab — housing radar processors, comms equipment, UPS, batteries — have their own dedicated cooling, often a precision air conditioning unit with N+1 redundancy and direct-expansion or chilled water cooling. The duct runs from the AHU to the cab are typically 0.8–1.0 mm galvanised, well-insulated, with very tight leakage class to maintain the humidity setpoint without excessive humidifier load.
Cargo terminal HVAC
The general cargo hall is a high-volume, low-occupancy space serving the sortation and handling of belly cargo and freighter aircraft loads. Cooling load is dominated by solar gain through the roof and any glazed loading dock walls, with internal heat from forklifts and conveyor motors. Most cargo halls in mild climates use natural ventilation through high-level louvres combined with mechanical extract; in hot climates VRF or evaporative cooling provides spot cooling at workstations and break rooms rather than full conditioning of the cargo hall.
Refrigerated cargo zones — pharmaceutical, fresh produce, perishable food — are insulated panel construction within the cargo hall envelope, with their own dedicated dehumidification AHUs, tight temperature control (typical 2–8°C for pharmaceutical cold chain, 0–4°C for fresh produce), and HEPA H13 filtration where pharmaceutical Good Distribution Practice (GDP) compliance applies. Ductwork in pharmaceutical cold rooms is typically 316L stainless steel for cleanability and corrosion resistance.
Fuel farm HVAC
The fuel farm — where Jet A-1 is stored in bulk above-ground or below-ground tanks and distributed via the apron hydrant system — is one of the highest-hazard zones on any airport. Any enclosed pump room, valve manifold building or below-grade vault is classified as ATEX/IECEx Zone 1 or Zone 2 depending on the operations performed inside.
Ventilation rate is typically 12 air changes per hour minimum in enclosed pump rooms, sized to maintain vapour concentration well below the lower explosive limit even under upset conditions. Fans are explosion-proof rated for the zone classification, ductwork is grounded, and the entire system is interlocked with leak detection sensors that increase ventilation rate or shut down the fuel handling system on detection.
Below-grade vaults — where valves and metering equipment are located in concrete pits — require dedicated extract from the lowest point of the vault because Jet A-1 vapour is heavier than air and pools at low elevations. The extract duct runs to grade level with explosion-proof fan and discharge well clear of any ignition source.
Materials selection
Material selection across the airport varies by zone, and the right specification per zone is one of the most cost-impactful decisions on the project. Over-specifying stainless across the entire terminal adds 15–25% to the duct subcontract; under-specifying galvanised in food courts and humid restrooms drives premature corrosion failures within 5–10 years of operation.
Galvanised steel G90 (Z275)
Galvanised G90 (American spec) or Z275 (European spec) is the workhorse material for general supply, return and exhaust ductwork in 0.6–1.2 mm gauge, fabricated per SMACNA, EN 1505/1506 or AS 4254.2 depending on the project standard. Use it for: concourse main supply trunks, gate hold room distribution, baggage handling makeup air, retail tenancy base-build supply, back-of-house circulation, plant room interconnects, and standard exhaust systems.
Fabric duct (Durkeesox, KE Fibertec, Prihoda style)
Permeable fabric duct is used in retail concourses, food courts and atria where: low installed weight matters, the visual finish is part of the architectural intent, fast installation supports an aggressive fitout schedule, and the supply distribution is from a long linear duct rather than discrete diffusers. Fabric duct is typically the final 5–15% of the supply train; the upstream trunks are still rigid galvanised.
316L stainless steel
316L stainless is specified for: restrooms (humidity and chloride exposure), commercial kitchens (grease and high humidity), food courts (humidity and cleaning chemicals), pharmaceutical cargo cold rooms (GDP cleanability), and any apron-facing ductwork directly exposed to deicing fluid or jet exhaust contamination. 316L is more corrosion-resistant than 304 specifically because of the molybdenum content, which resists chloride pitting.
Heavy-gauge galvanised or aluminised steel
Hangar HVAC, hangar door air curtains, paint booth ductwork and any zone exposed to mechanical impact from heavy equipment uses heavier 1.2–1.5 mm galvanised or aluminised steel. The aluminised coating provides better high-temperature performance for any duct near hot equipment exhaust.
Spiral round duct
Spiral-wound round ductwork in galvanised, stainless or pre-coated finishes is widely used in retail concourses, atria, lounges and any zone where round duct is part of the visual design. Spiral duct has lower installed cost than rectangular, lower friction loss for the same airflow, lower leakage, and integrates with helical hangers and architectural reveals. Spiral tubeformer machinery from SBKJ produces round duct in 80–2,000 mm diameter range for airport retail and atria applications.
Energy efficiency strategies
An airport terminal that has met ASHRAE 90.1 and NCC Section J on paper but not in operation is a common outcome of poor commissioning and BMS integration. The strategies below are the consensus minimum for any major terminal targeting genuinely low operating cost.
Economiser cycles
Economiser dampers on every AHU allow the system to draw 100% outside air when ambient conditions are cooler than return air. For an airport in a temperate climate (Sydney, Brisbane, Perth, Melbourne, most European cities), economiser cycle operates 30–50% of the year and can deliver 15–25% chiller energy savings annually. Economiser changeover requires accurate enthalpy or dry-bulb sensors at the outside air intake and the return path, and a control sequence that holds setpoint without short-cycling.
Demand-controlled ventilation
Demand-controlled ventilation (DCV) modulates the outdoor air rate based on actual occupancy, measured either by CO₂ sensors in the return air or by direct people-count sensors at entry doors. Airport DCV is unusually effective because occupancy varies dramatically between flight peaks and shoulder hours — a gate hold room may run from 250 occupants during boarding down to 5 occupants 30 minutes later. DCV can cut annual outdoor air loads by 20–40% in well-zoned terminals.
Free cooling overnight
Many airports run reduced operations overnight (typically 23:00–05:00 local), and the cool ambient temperature in this window allows the building thermal mass to be pre-cooled for the next morning's peak. Overnight free cooling cycles draw 100% outside air through the AHUs at low fan speed, transferring heat out of the structure and pre-conditioning the building for the morning peak.
BMS integration
Terminal-wide building management system integration is the single highest-leverage energy strategy. The BMS receives flight schedule data from airport operations, occupancy data from people counters and CO₂ sensors, weather data from on-site sensors, and sets the AHU, chiller and zone control sequences accordingly. A well-integrated BMS can deliver 25–40% energy savings versus a static-schedule operation.
See our commissioning and air balancing guide →
Construction phasing
Airport HVAC ductwork is rarely installed in a single mobilisation. The phased package model below is the consensus across major Tier 1 airport projects:
- Shell-and-core package (months 1–14 from main contract award): main supply and return risers, plant room interconnects, smoke extract main runs, atrium fabric duct primary supports. The shell-and-core duct is installed before the architectural fitout and provides the base infrastructure for everything that follows.
- Departures level fitout (months 8–22): check-in counters, security screening lanes, departures concourse, retail spine, food court. Departures fitout ductwork is the largest single linear-metre demand on the project.
- Arrivals level fitout (months 10–24): immigration, customs, baggage reclaim, arrivals concourse, kerbside meet-and-greet. Arrivals follows departures by 2–3 months on most projects so the same fabricator workshop can roll over to the next package.
- Retail and lounge fitout (months 16–28): individual retail tenancies, airline lounges, premium passenger areas. Tenant-driven scope often runs late as commercial deals close, requiring the duct fabricator to support short-cycle delivery for late tenancies.
- Apron and gate equipment (months 20–30): jet bridges, gate hold room final fitout, apron-edge equipment buildings.
- Commissioning, balancing and handover (months 28–34): air balancing per AABC or NEBB, smoke control commissioning per NFPA 92, fire damper testing, BMS tuning, 12-month seasonal commissioning return.
The phased model means the duct fabricator must hold workshop capacity over a 24–30 month delivery window, with monthly volumes varying 3:1 between the peak fitout phase and the shoulder phases. This is exactly the demand profile that drives investment in automatic duct lines — manual fabrication cannot deliver the peak volume, and standby capacity for fluctuating demand is expensive without automation.
SBKJ machinery for airport projects
Most airports do not directly procure HVAC duct fabrication machinery. The main contractor's mechanical subcontractor (or a specialist duct fabrication subcontractor under the mechanical) buys the machinery and operates it for the duration of the airport project, often running the same equipment across multiple subsequent projects. The machine specifications typical for an airport-scale duct workshop are:
SBAL-V Auto Duct Line
The SBAL-V Auto Duct Line is the workhorse for high-volume rectangular galvanised duct production. A typical SBAL-V configuration produces approximately 800–1,200 m² of finished rectangular duct per single shift, scaling up with multi-shift operation. For a terminal of 200,000–400,000 m² floor plate, total rectangular duct demand runs 50,000–120,000 m² of finished sheet metal, which a single SBAL-V can deliver across 18–30 months of phased fabrication.
Key specifications for airport application: coil width 1,250 mm to 1,550 mm to support the 1,500 mm wide duct sizes common in main supply trunks, automatic Pittsburgh seam closing, integrated TDF flange forming for fast site assembly, and Siemens or Mitsubishi PLC for repeatable control across long production runs.
SBTF Spiral Tubeformer
The SBTF Spiral Tubeformer produces round duct in 80–2,000 mm diameter range for retail concourses, atria, lounges and any zone where round duct is the architectural choice. Spiral duct has lower installed cost than rectangular, lower friction loss for the same airflow, lower leakage class out of the box, and integrates cleanly with helical hanger systems. Airport retail concourses and atria can demand 5,000–15,000 metres of spiral duct, with the SBTF producing 200–400 metres per single shift depending on diameter mix.
TDF Flange Former
The Transverse Duct Flange (TDF) joint is the consensus connection method for medium and high pressure class rectangular duct. TDF flanges form integrally on the duct edge, eliminating the bolt-on angle iron flanges of older construction, with much lower installed leakage. For airport smoke management ductwork rated 1,500–2,500 Pa, TDF flanges with high-density gasket and corner cleat closure are standard. SBKJ TDF flange formers run inline with the SBAL-V auto duct line or as standalone units in fabrication workshops.
Procurement and project delivery
Airport HVAC procurement typically follows the model below:
- Master plan and concept design (24–36 months before construction): airport master plan defines terminal layout, capacity targets and infrastructure scope. HVAC concept design establishes the AHU farm strategy, smoke management approach and energy targets.
- Schematic and detail design (12–24 months before construction): detail design develops the AHU schedules, duct layout, smoke control calculations and BMS strategy. Mechanical specification is issued for tender at this stage.
- Main contractor and mechanical subcontractor award (6–18 months before site mobilisation): the main contractor awards a mechanical package to a head mechanical subcontractor, who then awards a duct fabrication subcontract — usually to a specialist local fabricator running automatic duct lines.
- Duct fabricator equipment procurement (6–12 months before first delivery): if the fabricator does not already own adequate machinery, this is when SBAL-V auto duct lines, SBTF spiral tubeformers and TDF flange formers are ordered from suppliers including SBKJ. Lead time is typically 3–5 months from order to FAT plus 4–8 weeks shipping and 2–4 weeks installation and commissioning.
- Phased fabrication and delivery (24–30 months on a major terminal): shell-and-core, then fitout packages per the construction phasing above.
- Commissioning and handover (final 6 months of construction): air balancing, smoke control commissioning, BMS tuning, 12-month seasonal return.
Talk to an SBKJ engineer about your airport project →
Acoustic considerations
Airport HVAC noise targets are tighter than commercial buildings. Typical NC ratings: gate hold rooms NC 40, departures concourse NC 40, premium lounges NC 30, retail tenancies NC 35, ATC tower cab NC 30, MRO hangar NC 60. Achieving these targets across 30,000–80,000 L/s AHU airflows requires duct silencers at the AHU discharge, acoustic lining on the first 6–10 m of supply duct, low face velocity at supply diffusers (less than 2.5 m/s for NC 30 spaces), and careful attention to flanking transmission through the duct envelope.
Duct lining is typically 25–50 mm acoustic-grade glass wool with a tear-resistant facing for in-duct durability, or rigid acoustic board where higher attenuation is required. Coordinating acoustic performance with thermal insulation, fire performance and the tight pressure class on smoke extract is one of the trickiest detail problems on any airport project. Our acoustic duct lining and attenuator guide covers this in depth.
Climate-specific considerations
Tropical and subtropical airports
Tropical airports (Singapore, Manila, Mumbai, Brisbane in summer) face year-round high humidity loads, with dehumidification accounting for 30–50% of the cooling energy. Duct insulation thickness increases to manage condensation, and 316L stainless or coated galvanised is more common in food courts and restrooms because of accelerated chloride corrosion in humid coastal environments.
Hot arid airports
Hot arid airports (Riyadh, Dubai, Abu Dhabi, Perth) face extreme summer cooling loads with temperatures exceeding 45°C ambient. AHU design biases toward maximum economiser bypass during summer, oversized chiller capacity, and supply duct insulation specifically rated for high apron temperatures where ductwork passes near roof or apron zones.
Temperate airports
Temperate airports (Melbourne, Sydney, most European cities) have the largest economiser cycle benefit and the broadest range of operating conditions across the year. Duct design balances summer cooling and winter heating loads with substantial shoulder-season free cooling potential.
Cold-climate airports
Cold-climate airports (Hobart in winter, northern hemisphere airports) face deicing fluid contamination of outside air during winter operations, with corresponding upgrades to apron-facing AHU filtration and material selection. Snow and ice management on roof-mounted AHUs and exhaust stacks adds operational complexity.
Sustainability and embodied carbon
Major airport projects increasingly track embodied carbon as part of their sustainability targets. HVAC ductwork accounts for a meaningful portion of mechanical embodied carbon — galvanised steel manufacturing has a carbon intensity of approximately 1.9–2.4 kg CO₂e per kg of finished duct, with the zinc coating contributing an additional 0.05–0.10 kg CO₂e per kg. Strategies to reduce duct embodied carbon include:
- Specifying recycled-content galvanised steel where the supply chain supports it (typical recycled content 25–60% for primary mill product, higher for some secondary suppliers).
- Optimising duct sizing for air velocity rather than over-sizing for low pressure drop alone — every 10% reduction in cross-section reduces material consumption proportionally.
- Using fabric duct in retail and atria where the lower mass per linear metre delivers carbon savings beyond the operational energy benefit.
- Lifecycle alignment between duct service life (typical 30–50 years) and the building life (typical 50+ years for major airports), avoiding unnecessary replacement cycles.
Where airport HVAC specifications typically go wrong
The patterns below are the most common specification errors we see on airport projects when SBKJ engineers are brought in to support a duct fabricator on an airport scope:
- Smoke control duct under-specified for pressure class. Smoke extract risers running 1,500 Pa or more frequently get specified at 750 Pa pressure class because the design team used the supply duct spec by default. The result is excessive leakage in fire mode and a failed NFPA 92 commissioning test.
- Jet bridge HVAC treated as a single AHU per concourse. Sharing one AHU across 4–8 jet bridges defeats the redundancy that each bridge needs. The correct architecture is one dedicated AHU per bridge, mounted at the rotunda.
- MRO hangar specified at terminal pressure class. Hangar AHU connections regularly run 2,000–2,500 Pa to overcome the high static pressure of nozzle diffusers serving the hangar volume. Specifying these at terminal-grade 750 Pa class results in deformed duct and fan stall.
- Inadequate ATC tower redundancy. A single AHU serving the cab — or two AHUs sharing a single supply riser — defeats the redundancy requirement. Two physically separate AHUs and two physically separate risers is the only acceptable architecture for any commercial-traffic ATC tower.
- 316L stainless under-specified in food courts and restrooms. Galvanised duct in high-humidity food court back-of-house corrodes within 5–10 years and is expensive to replace once the building is in operation. Specifying 316L from day one is cheaper over the building life.
- Fire damper coordination missed at compartment boundaries. Smoke extract ducts must hold open in fire mode but close on smoke detection in the affected compartment. The BMS sequence and fire damper actuator wiring is frequently incomplete at handover and is the single largest source of late-stage commissioning issues.
- No allowance for tenant fitout late deliveries. Retail tenancies sign their leases late in the project, and the duct fabricator is often asked to deliver short-cycle fitout duct with 4–6 week lead time. A fabricator with adequate automatic duct line capacity can support this; a manual workshop usually cannot.
Regional considerations
SBKJ Group supports airport HVAC duct fabricators globally, with concentrated installed base in Australia, the Middle East, Southeast Asia and Latin America. Some regional patterns:
Australia and New Zealand
Australian airport projects layer AS 1668.2, AS 4254.2 and NCC Section J on top of the international stack. Most major fabricators in Sydney, Melbourne, Brisbane and Perth run automatic duct lines and spiral tubeformers, with SBKJ machinery supplying several of these workshops. See our Australia regional page for representative airport and infrastructure project history.
Middle East
The Middle East is the highest-volume airport HVAC market for the next decade — KSIA Riyadh, DWC Dubai, Abu Dhabi T-A, NEOM, KAEC, Doha and several other mega-projects collectively represent the largest concentration of new airport construction globally. Fabricator workshops in Riyadh, Dammam, Dubai, Sharjah and Doha are scaling auto duct line capacity rapidly. See our Middle East regional page for project history.
Southeast Asia
Singapore Changi T5, Manila NAIA upgrade, New Manila International (Bulacan), Jakarta Soekarno-Hatta T4, Kuala Lumpur expansion and various Vietnamese and Thai projects collectively drive substantial Southeast Asian airport HVAC demand.
India
Mumbai's existing T3 expansion, Navi Mumbai International Airport, Bengaluru T2, Delhi T1 expansion, Hyderabad expansion and several second-tier city greenfield airports drive Indian airport HVAC procurement.
FAQ
What is the typical HVAC duct lead time for a major airport terminal project?
For a greenfield international terminal of 200,000–400,000 m² gross floor area, plan for 18–30 months of duct fabrication and installation in phased packages: shell-and-core (months 1–14), departures fitout (months 8–22), arrivals fitout (months 10–24), retail and lounges (months 16–28). Western Sydney International, Brisbane T1 and Melbourne Tullamarine T2 all run this phased model. Order long-lead AHU equipment 14–18 months before commissioning and lock the duct fabricator's coil supply 6 months before the first ducted shell package.
What fire-rated duct rating is required for airport smoke management?
NFPA 92 requires the smoke exhaust system to maintain integrity for the design fire duration — typically 1 hour for atria up to 22 m, 2 hours for taller volumes. In Australia AS 1530.4 and AS 4254.2 govern fire resistance and leakage. Most airport designs specify EI 60 or EI 120 fabric-wrapped or board-clad galvanised duct on smoke extract risers, with TDF flange joints at 1,500 Pa or higher pressure class for low leakage.
How is jet bridge HVAC different from main terminal HVAC?
Each jet bridge is a small standalone zone served by a dedicated AHU of 3,000–8,000 L/s mounted at the rotunda. Differences: small volume but extreme glazing solar gain, condensation management on the bridge underside, fire damper at the terminal interface, and a separate Pre-Conditioned Air (PCA) unit for the docked aircraft. Bridges typically use 0.7–1.0 mm galvanised rectangular duct with TDF flange joints rated 500 Pa minimum.
Why do MRO hangars need a different HVAC approach to terminals?
MRO hangars are 30,000–150,000 m³ single-volume spaces with massive air change only when fueling or paint operations are active, low cooling load most of the time, large door openings that disrupt conventional ducted distribution, and explosion-proof zone classification anywhere fueling occurs. Terminal HVAC is high air change continuously, fine zone control, multiple smoke compartments, public-facing finishes. Hangars use heavy 1.2–1.5 mm galvanised duct with high static class; terminals use the full SMACNA range including light fabric duct.
What materials are used for airport HVAC ductwork?
Galvanised G90 (Z275) is standard for general supply, return and exhaust in 0.6–1.5 mm gauge. Permeable fabric duct is used in retail and atria for low weight, fast install and low condensation. 316L stainless is specified for restrooms, kitchens and food courts. Heavy-gauge galvanised is used for hangars where mechanical durability matters. Spiral round duct in galvanised or stainless is common in retail, atria and lounge ceilings.
How is smoke extraction designed for an airport atrium?
NFPA 92 requires smoke layer interface at least 1.8 m above the highest occupant level for the egress duration. For a 25 m high atrium with 50,000 m² floor plate, smoke exhaust runs 200–500 m³/s depending on design fire size and reservoir geometry. Duct sizing is typically 1.6–2.5 m equivalent diameter, fabricated in 1.2–1.5 mm galvanised or 304 stainless with TDF flanges and EI 120 wrap. Coordination with sprinklers, fire dampers and BMS is critical.
What ASHRAE 62.1 outdoor air rate applies to airport spaces?
Per ASHRAE 62.1-2022 Table 6-1: airport baggage areas 7.5 L/s/person plus 0.6 L/s/m², airport concourses 7.5 L/s/person plus 0.3 L/s/m², waiting areas 3.8 L/s/person plus 0.3 L/s/m², gate area lounge 3.8 L/s/person plus 0.3 L/s/m², lobbies 3.8 L/s/person plus 0.3 L/s/m². Australian projects under AS 1668.2 use a similar approach. Demand-controlled ventilation tied to BMS occupancy is standard for ASHRAE 90.1 and NCC Section J energy compliance.
Where does SBKJ machinery fit in an airport HVAC project?
Main contractors split the HVAC package between long-lead plant (AHU, chillers, BMS) and the duct fabrication subcontract. The duct fabricator runs SBKJ auto duct lines for high-volume rectangular galvanised duct (SBAL-V Auto Duct Line V), SBKJ spiral tubeformers for round duct in retail, atria and lounges (SBTF series), and SBKJ TDF flange formers for high-pressure-class smoke extract and AHU connection ducts. SBKJ machines have shipped to fabricators serving airport projects in 60+ countries.
