Coffee Shop and Hawker Stall Exhaust in Singapore: What's Different

A coffee shop or a hawker stall is not a small restaurant. It looks like one from the ventilation contractor's side — hoods, ducts, a fan — but almost everything that makes exhaust design difficult is different, and applying restaurant thinking to a coffee shop is how operators end up with a system that never quite works and a cleaning bill nobody expected.

The differences come down to four things: several tenants sharing one system, cooking that is heavier than the floor area suggests, a duct run that was designed for the building rather than for the stalls, and nobody owning the maintenance. Here is what each does in practice.

One system, several stalls, no single owner

In a restaurant, one operator owns the kitchen, the hood, the duct and the fan, and one operator suffers when any of them is neglected. In a coffee shop, the hood over each stall may be effectively the stallholder's, the shared duct and the fan belong to the operator or the landlord, and the stallholders change over the years while the ductwork does not.

That split is the single biggest cause of neglected coffee shop exhaust systems. Each stallholder cleans what they can see — the filters and the visible part of the canopy — because that is what is theirs and what an inspection looks at first. The shared horizontal duct running above the ceiling, which is where grease actually accumulates and where a fire actually travels, belongs to everyone and therefore to no one.

If you operate or lease a coffee shop, settle in writing who is responsible for the shared duct and the fan, and how often it is cleaned. Doing this at the start of a tenancy is a five-minute conversation. Doing it after a grease fire is a dispute.

The cooking is heavier than the space suggests

Stall cooking in Singapore is concentrated and intense. A single wok stall running through a lunch peak puts out more grease-laden vapour and more heat than a considerably larger Western kitchen doing plated food, because the cooking method is high-heat and continuous rather than intermittent.

Two consequences follow, and both are routinely underestimated:

• Grease loading is high and fast. A cleaning interval that would be sensible for a café is not sensible for a wok or deep-fry stall. The correct interval is set by what is being cooked and how much, not by the size of the premises or by the calendar.
• Heat rejection is a real problem. Stallholders work directly under the hood, often in a narrow space, with burners running for hours. If the exhaust is pulling but nothing is replacing the air properly, the space becomes genuinely unpleasant to work in and the hood stops capturing well at the same time.

That second point is worth dwelling on, because it is the most common complaint we hear and the least often diagnosed correctly. When a coffee shop is too hot and too smoky at once, the instinct is to ask for a bigger fan. A bigger fan often makes it worse. Which brings us to the part almost everyone gets wrong.

Make-up air is the thing that gets forgotten

Every cubic metre of air pulled out of the premises has to be replaced by a cubic metre coming in. If it is not deliberately supplied, the building finds it anyway — under doors, through gaps, and from the dining area.

In a coffee shop this shows up in a very recognisable set of symptoms: smoke rolling out from under the front edge of the hood instead of going up it, a door that is heavy to open or slams, the dining area smelling of the stall furthest from the entrance, and the fan running hard while capture is visibly poor. All of those are one problem wearing four costumes.

Adding fan capacity to an already air-starved space increases the imbalance. The fix is to look at what is coming in, not only at what is going out. We wrote about this in more depth in make-up air and air balancing in a commercial kitchen, and the principle applies more sharply in a coffee shop than almost anywhere else, because the premises are usually more enclosed and more heavily cooked in per square metre.

The duct run was designed for the building, not the stalls

Restaurant ductwork tends to be designed once, for one kitchen, with a reasonably direct route to the discharge point. Coffee shop ductwork frequently is not. It has to serve several stall positions, get around structure, and reach a discharge point the building already decided on, which often means long horizontal runs and more bends than anyone would choose.

Long horizontal runs matter because grease settles in them. Bends matter because they add resistance and collect deposits at the turn. Both mean that the parts of the system most in need of cleaning are the parts hardest to reach — and if access panels were not built in at the right intervals, cleaning becomes partial by default.

When a stall changes hands and the new tenant cooks differently — a drinks stall replaced by a fried food stall, say — the duct serving that position is now carrying a load it was never sized or routed for. That change is invisible on paper and very visible in the ductwork a year later.

What NEA and SCDF care about does not change

The obligations do not scale down because the premises are small. A coffee shop still has to keep its exhaust system clean enough not to be a fire risk and not to be a nuisance to neighbours, and a fire in a stall still travels through the ductwork the same way it does anywhere else. The two posts worth reading alongside this are what NEA expects from your kitchen exhaust system and how a grease fire travels up kitchen ductwork.

Odour complaints deserve their own mention, because coffee shops attract them more than restaurants do. They tend to sit closer to residential blocks, they cook for longer hours, and the discharge point is often lower and nearer to windows. A complaint is usually a discharge and design problem rather than a cleaning problem, and cleaning alone rarely settles it.

What to actually do

• Know who owns the shared duct and fan, in writing, before a tenancy starts.
• Set cleaning frequency by the heaviest stall, not by an average of the premises. One wok stall sets the interval for the duct it discharges into.
• Check make-up air before adding extraction. If the doors are heavy and the dining area smells, a bigger fan is not the answer.
• Ask where the access panels are. No access means no cleaning of the section that matters most, whatever the invoice says.
• Re-assess when a stall changes cooking type, not just when it changes hands.
• Get the before-and-after records from whoever cleans it. Photographs of the inside of the duct are the only honest evidence that the shared run was actually done.

The short version

A coffee shop concentrates heavy cooking into a small, enclosed, shared space with ductwork that was routed for the building rather than the stalls, and with no single person responsible for the part that matters most. Fix the ownership question and the make-up air question first — most of the rest follows from those two.

Talk to us about your premises

Tell us how many stalls share the system and what the heaviest one cooks, and we will tell you what the interval should be and whether the layout is working against you. Message us on WhatsApp, or see kitchen exhaust cleaning and commercial kitchen ventilation.