Extraction and ventilation
Removes the heat, moisture and odour a bar generates continuously, and brings in the air needed to replace what is taken out.
Ventilation is a balance, and the half everybody forgets is the supply half. Air removed from a room has to be replaced, and if no replacement path is designed the room finds one: through the entrance door, which then becomes hard to open and lets in unconditioned outside air at the customer's back; through a gap into a service corridor, dragging its smells the wrong way; or nowhere at all, in which case the extract fan simply stops moving the air its rating claims and everybody concludes the fan is undersized. MAKE-UP AIR IS THE MECHANISM, and it is the reason two identical fans perform completely differently in two rooms. What a bar actually generates is worth separating, because the three loads want different answers. Heat comes off espresso boilers, brewers, hot-water systems, dishwashing and every self-contained refrigeration condenser in the room — refrigeration is the one people leave out, and it is the one that grows through the day. Moisture comes off steaming, hot washing and any open hot water; in a hot humid climate the outside air is already carrying moisture, so the room's dehumidification burden is not a small correction. Odour is generated by waste, by milk, and by anything cooked. And that last category changes the subject entirely: WHERE COOKING OR ANY GREASE-LADEN OR SMOKE-PRODUCING PROCESS IS PRESENT, this stops being comfort ventilation and becomes a specified extract system with fire-safety implications, and the requirement is set by local code and by the fire authority, designed by a mechanical engineer against the actual appliance schedule, and confirmed in writing before installation. This platform states no air-change rate, no extract velocity, no duct size, no canopy dimension and no fan rating. Not because the numbers are unknown, but because the correct ones for a given room are a calculation somebody signs their name to.
- Start from the appliance schedule and the room, and take the answer from a mechanical designer. What is required, whether a canopy is needed at all, and everything about its extent and construction are determined by local code and confirmed by the authority having jurisdiction and the fire authority. This is the item on this page where a confident guess is most expensive.
- State every heat source in the room when the assessment is done, including the ones that are not appliances: self-contained refrigeration condensers, the ice machine, lighting and the people. Refrigeration in particular is left off almost every list, and it is the load that rises as the day and the room warm up.
- Design the make-up air path at the same time as the extract, in the same conversation, and refuse to let it be value-engineered separately. Extract without supply is a fan that does not achieve its rating and a room that solves the problem through your front door.
- Ask what happens in the worst season, not on the commissioning day. A hot, humid outside condition changes both the cooling and the dehumidification burden, and a system signed off in mild weather can be inadequate in a way nobody discovers until the first peak.
- Treat noise as part of the specification, because it is permanent and it sits above the people who work under it. A system that is loud enough to make the team raise their voices for an entire shift will be switched off, and a system that is switched off has no rating at all.
- Confirm the cleaning and maintenance regime before installation, along with the access route for it. Filters, grease-bearing surfaces and ducts all have a required regime, that regime is part of what the authority signs off, and a system nobody can reach is a system nobody cleans.
- Check where the extract discharges and what is near it, because a discharge position is a neighbour question and a licensing question as much as an engineering one. It is a common cause of a complaint that arrives after opening, when it is expensive to answer.
- Get the confirmation in writing and keep it with the commissioning records. Verbal assurance from an installer is not a sign-off, and the person who asks for the paperwork at inspection will not be the person who gave the assurance.
It is the only item in this section that is not positioned relative to the barista, because it is positioned relative to the loads. Extract belongs over what generates heat and moisture, make-up air belongs where it will not blow across a working position or a customer, and neither may be moved to suit the layout once the ceiling is closed. That inversion is why ventilation is assessed before the bar is drawn rather than after — every other decision in this file can be adjusted around a finished room, and this one cannot.
- Specifying extract without a designed make-up air path, then ordering a larger fan when it underperforms.
- Assessing the ventilation from appliance nameplates alone and leaving out refrigeration condensers, lighting and the people in the room.
- Signing a system off in mild weather and discovering in the worst season that the assessment never included it.
- Assuming comfort ventilation is enough where a grease-laden or smoke-producing process is present, which is a fire-safety matter and not a comfort one.
- Treating an installer's verbal assurance as a sign-off, with nothing in writing to show at inspection.
- Installing a system whose cleaning regime cannot be performed because nobody drew the access route.
- Ignoring noise at specification, and being surprised that a system the team cannot talk over gets switched off.
- Choosing the discharge position last, and finding out after opening that it faces something or somebody it should not.
- What is required is determined by the appliance schedule, the process taking place, the volume and construction of the room and the local code — assessed by a mechanical designer and confirmed by the authority having jurisdiction, with the fire authority governing anywhere a grease-laden or smoke-producing process exists. Extract and make-up air are specified together or the specification is incomplete. This site states no air-change rate, no velocity, no duct size and no fan rating.
- The room condition a bar has to hold is a design input, not an outcome, and in a hot climate it is the input that sizes everything. Every appliance in the room rejects heat into it continuously and refrigeration rejects more of it as the room warms, which is a feedback loop rather than a fixed load. Say what condition the bar must hold and let the mechanical designer work back from it.
- Fans, controls, any interlock with an appliance and any fire-safety provision associated with a canopy are all electrical work, and where an interlock is required it becomes a safety function rather than a convenience. Its design, protection and commissioning are for a licensed electrician working with the mechanical designer, under local code; this site states no rating, no phase and no circuit arrangement.
- Anything installed overhead has to be reachable for the cleaning regime it is signed off with, and it must not sit where it forces a person to work stooped or reach past it. Draw the access route at the same time as the system; an access route added later is usually a ladder in the middle of the bar.
- General room ventilation only
- The bar relies on the building's air handling with no extract dedicated to the bar position.
- It is adequate only where the heat and moisture generated are genuinely small and the room is generously served, which is a narrower set of sites than it appears from the plan. Its failure is gradual and seasonal — a bar that is comfortable in the cooler months and unworkable in the warm ones — and by the time it is understood the ceiling is closed.
- Dedicated local extract at the bar
- An extract point serving the bar position specifically, sized against what the bar itself generates rather than the room average.
- It treats the load where it is produced, which is always cheaper than treating a whole room, and it is the arrangement that keeps a bar workable when the room is full. It only performs as designed if the make-up air path is designed with it — extract specified alone is the most common ventilation error there is.
- Canopy or hood over a defined appliance group
- A captured hood over appliances producing heat, steam, grease-laden vapour or smoke, with its own extract and its associated safety provisions.
- Where any grease-laden or smoke-producing process exists, this is not one option among several — it is a code-driven requirement whose extent, construction, cleaning regime and fire-safety provisions are all determined by the local authority and the fire authority against the appliance schedule, and confirmed before installation. It also changes the building: a duct route, a discharge position, structural support, an access route for cleaning, and a service contract. None of that can be retrofitted quietly.
- Designed make-up air path
- A deliberate supply route bringing replacement air into the space in a controlled way, rather than letting the room draw it through whatever gap it finds.
- It is what makes the extract actually work, and it is the line most often deleted from a budget because it removes nothing visible. Its absence shows up as doors that are hard to open, draughts across the customer, smells travelling from a service area into the room, and an extract system everybody believes is undersized when it is in fact starved.
- The entrance door becomes hard to open, or whistles, whenever the bar is running at full load.
- Extract with no designed make-up air path, so the room is at negative pressure and drawing its replacement air through the only opening available.
- Guest comfort, an extract system underperforming its rating, and often odour pulled the wrong way through the building. It is regularly answered by ordering a bigger fan, which makes the negative pressure worse.
- The bar is comfortable in the morning and progressively unworkable through the afternoon, every day, with no change in throughput.
- Cumulative heat rejection into a room whose ventilation was assessed on appliance nameplates without the refrigeration condensers, the lighting and the people, and without the worst outside condition.
- Staff performance and retention, refrigeration running harder in the hottest part of the day, and drink quality behind both. The daily shape is the diagnostic: a load that builds is a heat balance problem, not a fan fault.
- Condensation on cold surfaces, on the inside of glazing, or a persistent damp smell in an enclosed part of the bar.
- Moisture from steaming and hot washing with nowhere to go, in a space where the outside air is already humid so infiltration adds moisture rather than removing it.
- Building fabric and joinery first, then a hygiene problem in whatever the damp is sitting in. It is slow, it is expensive to reverse, and it is usually visible for a season before anybody treats it as a ventilation finding.
- The system is switched off during service, by the team, deliberately.
- Noise, a draught landing on a working position, or both — a specification that treated the system as a rating rather than as something people stand under for eight hours.
- Everything the system was installed to do, plus a compliance gap if the extract is part of what the site was signed off with. Ask whether it is running before you ask whether it is adequate.