Singapore packs one of the highest densities of food outlets in the world into a very small land area. Hawker centres, shophouse restaurants, mall food courts, hotel kitchens and central kitchens often share the same building envelope, the same service riser and the same neighbours. That density is why kitchen exhaust is regulated by more than one agency, and why a ventilation design that passes one review can still stall at the next. The three authorities that matter most are the Singapore Civil Defence Force (SCDF), the National Environment Agency (NEA) and the Singapore Food Agency (SFA), with URA, HDB and the building owner or MCST controlling the flue as a piece of the building itself.
Four Reviewers, One Exhaust System
Singapore does not have a single kitchen exhaust approval. It has a sequence. At building plan stage, the Qualified Person — an architect or professional engineer — designs the system to NEA’s Code of Practice on Environmental Health (COPEH) for siting and air cleaning, and to the SCDF Fire Code for duct construction and fire protection. The SFA then checks its pre-licensing requirements before the food shop licence is issued, including the air cleaning system, the discharge point, make-up air, negative pressure and cleanable ducts with inspection openings. If the premises sit inside a conservation shophouse, URA must agree to the flue’s plan and elevation. If they sit in HDB premises, HDB renovation guidelines apply. If they sit in a mall or strata building, the MCST or landlord adds conditions on riser capacity, rooftop loading, noise and access.
The practical consequence is that the exhaust design must be coordinated with the tenancy, the building and the menu from the beginning. A unit that looks suitable for a restaurant may still be unsuitable for heavy wok cooking if there is no approved route for grease-laden air to reach the roof.
SCDF Fire Code Clause 7.1.13: The Duct Rules
The SCDF Fire Code treats kitchen exhaust as a fire-containment problem first and a comfort problem second. Clause 7.1.13 sets the core requirements for a commercial kitchen exhaust system.
Independence. A mechanical exhaust system serving the cooking area of an eating establishment must be independent of those serving other parts of the building. It cannot be merged with general toilet, car park or office exhaust.
Clearance to combustibles. The hood and ducts must maintain a clearance of 500 mm from unprotected combustible materials. Where that clearance cannot be maintained, a fire-rated enclosure or wrap is required.
Discharge. The exhaust must discharge directly to external space, or to an air shaft, and must be at least 5 m from any air intake opening. That distance protects the building’s own fresh-air system from re-entraining cooking effluent.
Fire rating outside the kitchen. Where the exhaust duct runs outside the kitchen, it must either be enclosed in a structure or constructed to give at least the same fire rating as the kitchen, or that of the room it traverses, whichever is higher. The rating applies to fire exposure from both the interior and the exterior of the duct. Where a duct riser must be enclosed in a protected shaft, it must be compartmented from other ducts or services in the same shaft.
No fire dampers. Fire dampers must not be fitted inside kitchen exhaust ducts. A damper that closes on a grease fire can trap heat and pressure in the duct instead of containing the problem at the source.
Access panels. The duct must be provided with openings via access panels so that inspection and cleaning are physically possible. Access panels are expected at bends and at regular intervals along the run, including both horizontal and vertical sections.
Separation from openings and LPG. A kitchen exhaust duct running outside a building must not be located within 3 m of any unprotected opening, reduced to 1.5 m only where the opening is on the same plane as the duct. A non-fire-rated duct must not sit above an LPG storage cabinet unless separated by at least 2-hour fire-rated masonry above and beside the cylinders. Non-fire-rated duct must stay at least 3 m from unprotected LPG cylinders and at least 600 mm from a vapouriser or liquid-phase LPG pipeline.
Shared Exhaust in Food Courts and Small Outlets
Sharing a kitchen exhaust system is allowed in Singapore, but only under defined conditions. For food courts, the court must be under a single ownership or operator, and all kitchen exhaust ducts running outside the food court must have a 1-hour fire resistance rating, or not less than that of the elements of structure, whichever is higher.
For restaurants and small F&B outlets, the conditions are tighter. The outlets sharing the system must be on the same storey, within an aggregate zone area not exceeding 2,000 m², with a maximum first-to-last length of 50 m. The aggregate floor area of the outlets must not exceed 1,000 m². A common duct must be served by a common exhaust fan. The zone must be protected by an automatic fire sprinkler system. Each exhaust hood must be fitted with a wet chemical fire extinguishing system. The common duct running outside the restaurants must have a 1-hour fire resistance rating, or not less than that of the elements of structure, whichever is higher.
In dense mixed-use buildings, this is often the clause that decides the kitchen layout. Two adjacent units may look like a natural shared-riser project, but if they fall outside the 2,000 m² / 50 m / 1,000 m² envelope, each unit needs its own exhaust duct.
NEA’s Air Cleaning Outcome Test
NEA regulates kitchen exhaust as an environmental health issue. Its Code of Practice on Environmental Health (COPEH) does not certify a technology by brand or model. It requires that fumes from the cooking range be extracted immediately and treated by an air cleaning system that captures particulate matter, grease, oil and water vapour, so that no visible smoke and fumes leave the outlet.
That wording matters. The officer checks the outcome at the outlet, not the equipment schedule. In practice, a washable baffle grease filter is commonly used as the first stage, followed by an electrostatic air cleaner for fine particulate and visible smoke, then activated carbon or another gas-phase stage for odour. Electrostatic precipitation is therefore one accepted route to the visible-smoke test, but it is not the only one, and odour is treated as a separate gaseous problem that particulate removal alone will not solve.
Discharge location is the second NEA issue. The default is to exhaust above the roof. Only where that is not practical may an alternative outdoor discharge point be chosen, and then it must not face adjacent buildings, with separation measured horizontally from the outlet to the facade it faces. NEA also keeps outlets more than 5 m from cooling towers, and requires aesthetic screening where the outlet is close to homes. The SFA pre-licensing checklist adds that the outlet must face away from, and be screened from, the immediate neighbouring premises.
SFA Pre-Licensing: Make-Up Air and Cleanability
SFA checks the exhaust system before the food shop licence is issued. Its pre-licensing requirements cover the air cleaning system and roof-level discharge as NEA describes them, sufficient make-up air with negative pressure while the hood is running, non-combustible, smooth and cleanable ducts with inspection openings, and the 12-month degreasing record, which officers ask for during inspections.
Make-up air is the item most often under-designed. A kitchen that exhausts more air than it brings in will run at negative pressure. Doors become hard to open, the dining area loses conditioned air through the service opening, and cooking performance suffers because the hood loses capture. In Singapore’s climate, make-up air also has to be tempered. An untempered supply in a hot, humid afternoon adds latent load to the kitchen and can cause condensation on cold surfaces. Balanced supply and exhaust design is therefore part of the licence condition, not an optional comfort upgrade.
Capture, Sizing and the Two-Phase Rule
Singapore’s local cooking pattern is heavy on wok, grill and deep-fry. Wok hei cooking produces a high-velocity plume with fine oil aerosol and intense odour. Char-grilling adds smoke and sub-micron particulate. Deep frying produces a continuous grease aerosol that loads a hood quickly. Chilli, belacan, curry and spice pastes add strong volatile organic compounds that linger in the airstream.
The capture geometry that follows is familiar from international practice. Hood overhang should be at least 150 mm on each side and 300 mm at the front. Mounting height is typically 600–800 mm above the cooking surface for a Type I hood, with higher mounts requiring more airflow. Face capture velocity is designed in the 0.25–0.35 m/s range. Trade heuristics such as 2,000–2,500 m³/h per metre of hood, or roughly 4,000 m³/h per burner, give a first estimate, but the actual figure should come from the hood face area and the required capture velocity.
The treatment sequence should always remove particulate before gas. If activated carbon is placed upstream of an electrostatic stage, the carbon blinds with grease and the odour stage fails within weeks. In a ducted system the order is baffle or pre-filter, then an electrostatic precipitator stage, then a gas-phase odour stage. A self-contained ductless range hood family applies the same order inside the unit and recirculates cleaned air back into the kitchen.
Dense Buildings, Shophouses and Make-Up Air Constraints
Singapore’s building stock creates constraints that a greenfield kitchen does not have. Mall food courts often come with a designated exhaust riser and a fixed fan capacity, and the landlord may restrict which unit can connect. Older shophouses in conservation areas such as Tanjong Pagar, Chinatown and Kampong Glam have limited roof penetrations, and URA must agree to the flue’s appearance. HDB eating houses follow their own renovation rules. Central kitchens in industrial buildings may share a loading bay and a roof with other trades, so discharge must avoid neighbouring air intakes and cooling towers.
Where the building cannot support a roof-level discharge, the fallback is usually a treated low-level discharge using an electrostatic stage plus carbon, subject to NEA and MCST approval. Where even that is impractical — small kiosks, pop-up kitchens, events and temporary catering — a ventless catering cart provides a self-contained cooking and extraction platform with no fixed duct route.
Noise, Vibration and Neighbour Relations
Singapore’s density means exhaust noise is not a minor issue. A rooftop fan or a duct-mounted unit close to a residential unit can generate complaints under NEA’s noise framework. Designers should specify fan selection for the actual system pressure, use vibration isolators, and avoid placing high-velocity ductwork directly against a party wall. Odour and noise complaints are the two most common triggers for an NEA inspection of a food premises, and both are influenced by the exhaust design long before the first service.
Fire Suppression, Gas Interlocks and Extinguishers
SCDF requires commercial exhaust hoods to be fitted with an automatic wet chemical fire extinguishing system, typically to NFPA 17A or an accepted equivalent. The system must cover the cooking equipment, the hood plenum and the duct entry point. When it activates, it must shut off the gas supply and stop the exhaust fan, so that the suppressant is not pulled away from the fire before it can work. This interlock is one of the most common points of coordination failure between the exhaust contractor and the suppression contractor, and one of the most common reasons an SCDF submission is returned for revision.
Portable extinguishers in commercial kitchens are expected to conform to SS EN 3 and be maintained under SS 578. LPG installations need leak detection linked to automatic shut-off and adequate ventilation, with cylinders sited away from the exhaust duct and unprotected openings. Fixed suppression and compartmentation between the kitchen and the dining area must meet the relevant fire-resistance ratings, and activation tests must be documented in the Fire Safety Instruction Manual.
Cleaning: The 12-Month Floor and the Real Interval
SCDF requires the entire exhaust duct, interior and exterior, and the kitchen hood to be degreased and cleaned at least once every 12 months, by a specialist, with records kept by the owner or operator and written into the Fire Safety Instruction Manual. That 12-month rule is a floor, not a target. NEA’s COPEH repeats the same requirement, and SFA officers check the exterior of the system and ask for the records during inspections.
In practice, most Singapore F&B kitchens fall into a shorter cycle. The NFPA 96 framework that the industry uses sets inspection intervals by cooking load: monthly for solid-fuel cooking, quarterly for high-volume 24-hour, charbroiling or wok operations, semi-annually for moderate volume, and annually for low-volume operations. Heavy wok, grill and deep-frying kitchens in Singapore commonly need cleaning every one to three months. Air cleaning equipment such as grease filters, electrostatic cells and carbon media are maintained on the manufacturer’s own schedule, separate from the annual duct clean.
A compliant clean should cover the hood inside and out, the filters, the accessible duct interior and the exhaust fan, with dated before-and-after documentation. Cleaning only the visible stainless and skipping the duct interior and fan leaves the fire fuel in place.
Ducted Default and Honest Ductless Boundaries
Singapore treats a ducted, externally venting grease exhaust as the default. A ductless or recirculating hood is not prohibited, but it must still meet the same capture geometry, the same grease filtration intent and the same fire-safety coverage, and it must be accepted by NEA, SFA and SCDF for the specific premises. In practice, a recirculating design is most defensible where the building genuinely cannot support a duct route — small kiosks, heritage shophouse tenancies with no approved penetration, mall units with no riser allocation, or temporary event kitchens.
For heavy wok, char-grill, tandoor and deep-fry lines, the default remains ducted extraction to atmosphere with a properly sized electrostatic stage and odour control. For light- and medium-load kitchens such as cafés, bakeries, dessert counters and small fast-casual units, a self-contained ductless hood with electrostatic precipitation and activated carbon can satisfy the hygiene, visible-smoke and comfort objectives while avoiding an unbuildable duct route.
Matching Architecture to the Load
Light-load and retrofit scenarios can use a recirculating ductless hood that combines a multi-stage electrostatic cell with a gas-phase odour stage. Heavy-grease and solid-fuel lines need ducted extraction with an electrostatic precipitator followed by carbon, plus a centrifugal fan sized for the full system pressure loss. Where headroom or riser rules prevent a stacked in-line unit, a split cabinet arrangement places the purification module on the floor and connects it to a shallow canopy with a short grease-tight duct. Odour-sensitive sites close to residents or hotel rooms benefit from adding a dedicated odour removal tower downstream of the particulate stage.
For operators running several outlets, standardising on one or two platform concepts simplifies maintenance, spare-parts holding and staff training, while still allowing local adjustment for menu and building.
The Compliance File Inspectors Ask For
A compliant installation is only the start. The file should contain the approved ventilation drawings, the Qualified Person’s design basis, the fan schedule and commissioning report, the wet chemical suppression certificate and its maintenance record, the 12-month degreasing certificate with before-and-after photos, the grease trap or interceptor certification, the make-up air and negative pressure check, and the Fire Safety Instruction Manual entry. SFA officers, SCDF inspectors, the landlord and the insurer may each ask for a different part of it.
Operators should also keep daily hood and filter wipe-down logs, weekly grease-cup emptying records, and periodic electrostatic cell washing records. A system that is never cleaned fails on visible smoke, odour, airflow and fire risk at the same time, and the failure usually arrives during a busy service rather than at a convenient inspection.
