Extraction for a bakery against a restaurant kitchen

Bakery extraction planning requirements look lighter than those for a restaurant kitchen, and in one respect they are: baking produces very little grease, so the filtration train is shorter and the ductwork is easier to keep clean. In every other respect a bakery is no simpler. It produces more moisture, a visible plume, considerable heat and a dust problem at the ingredient end, and the planning procedure is identical. What changes between the two is the abatement specification, not the application you make.

Why the two produce different problems

Restaurant cooking, particularly frying, grilling and charring, releases grease aerosols, particulates and a high intensity odour that people find objectionable at low concentrations. The odour carries, it deposits on surfaces, and it persists in soft furnishings. That is the combination that generates complaints.

Baking releases a lower intensity odour that most people find acceptable or pleasant, and almost no grease. What it releases instead is water vapour, in volume, together with heat from oven exhaust and proving rooms.

The consequences diverge from there.

The operating hours line is the one applicants underestimate. A bakery's fans run when the background sound level is at its lowest and bedroom windows are open, which makes a modest fan a much bigger problem at 4am than a larger one at 8pm.

Grease laden air and the abatement it needs

For a restaurant kitchen the national guidance on controlling odour and noise from commercial kitchen exhaust systems is the reference point, and it works by classifying the odour risk from the type of cooking, the size of the kitchen and the proximity of receptors, then specifying a level of abatement to match.

The train normally runs in this order.

1. Canopy with baffle or mesh grease filters, sized for an adequate capture velocity across the face.
2. Secondary grease filtration where the risk classification requires it.
3. Odour abatement, typically activated carbon, electrostatic precipitation, or an oxidation stage, selected on the assessed risk.
4. Fan, positioned so that the duct upstream of it is under negative pressure where practicable.
5. Vertical discharge at roof level.

Specify each stage with a product and a performance figure. An application that says a suitable filtration system will be installed is not a specification, and the condition that follows will require the whole thing to be submitted again before the use can begin.

What a bakery actually has to control

Three things, none of them grease.

Moisture. Saturated air cools in the duct, condenses, and runs back down to the lowest point. Ducts need to be insulated, laid to fall, and fitted with a drain point. Omitting that produces water staining on a neighbour's wall and a complaint that looks like a leak.

Plume. A visible steam plume in winter is routinely reported as smoke, and a discharge point near an upper floor window will generate complaints regardless of its odour content. Discharge height and velocity do more to solve this than any filter.

Dust. Flour dust is a sensitiser and a workplace exposure issue governed by the control of substances hazardous to health regime, with local exhaust ventilation at tipping and mixing points. It is not usually a planning matter, and it affects the planning drawings because the extract ducts have to go somewhere.

Where a bakery also fries, for doughnuts or savoury products, it is a restaurant kitchen for abatement purposes and should be assessed as one.

Duct routing, termination and discharge velocity

Routing is where schemes fail, and it is an architectural problem before it is a mechanical one.

The duct has to get from the kitchen to roof level, and in a terraced parade the only routes are internal through the floors above, which needs the upper owner's consent and fire stopping at every compartment, or external up the rear elevation, which is a visual matter and in a conservation area a contentious one.

The national guidance expects vertical discharge at roof level, terminating above the roofline rather than at eaves level or into a courtyard, at a velocity high enough to carry the plume clear of the building. Discharge into an enclosed rear courtyard is the single commonest cause of refusal, because the plume recirculates and the courtyard is usually surrounded by windows. Check the current edition of the guidance for the recommended termination heights and efflux velocities rather than copying figures from an older report.

Two further points. A cowl or weather cap that deflects the discharge downwards defeats the whole arrangement and should not be specified. And the duct's external appearance needs showing on the elevation drawings, in a finish the authority has agreed, because a galvanised duct up the back of a listed building is a separate consent problem.

A Ventilation and Extraction Statement is the document that pulls the routing, the specification and the discharge arrangement together in the form environmental health officers expect.

Fan noise and how it is assessed

Plant noise is assessed against the British Standard method for rating industrial and commercial sound, comparing a rating level for the plant with the measured background sound level at the nearest noise sensitive position.

For a bakery the assessment has to be done at the relevant time of day, which means overnight monitoring. An assessment carried out between 10am and 4pm tells you nothing about a 4am start.

Four specification decisions reduce the result.

• A larger, slower fan moving the same volume of air, because tip speed drives the noise
• An attenuator on the discharge, sized for the frequency content rather than a nominal insertion loss
• Anti vibration mounts and a flexible connection, because structure borne vibration transmits through a party wall and is not fixed by an acoustic enclosure
• Positioning the fan away from facades and courtyards, and never on a party wall

Refrigeration plant raises the same issues with a different duty cycle, and our note on cold stores and refrigeration plant noise covers the overnight running pattern in detail. Councils expect acoustic work from a suitably qualified author, and a Noise Impact Assessment with monitoring data behind it is what persuades an environmental health officer, with professional review before submission strongly advised.

Maintenance access and cleaning regimes

A system that cannot be cleaned stops working, and an authority that has dealt with one such case will ask about access.

Provide cleaning access panels at intervals and at every change of direction, sized to allow internal cleaning, and show them on the drawings. State the proposed cleaning frequency, which for a grease bearing system depends on daily operating hours, and the arrangements for replacing carbon media. Keep a log.

For a bakery the equivalent items are the condensate drain, the moisture barrier and the dust extract filters. Less onerous, and still worth writing down, because the maintenance schedule is usually a condition.

What the environmental health officer expects to see

Eight documents, and the absence of any one of them delays the discharge of the condition.

1. An odour risk assessment classifying the cooking or baking operation and the proximity of receptors.
2. A plant schedule with fan duty, fan curves and octave band sound data.
3. The abatement specification, by product and performance.
4. Canopy drawings with capture velocities.
5. Duct route drawings in plan and section, with the termination point shown on the elevations.
6. An acoustic assessment with background monitoring at the relevant time of day.
7. A commissioning and testing proposal.
8. A maintenance and cleaning schedule.

Where the odour case is contested or the receptors are close, a standalone Odour Assessment addressing dispersion and the assessed risk category is the document that resolves it, and councils usually expect a suitably qualified author with professional review before submission.

Conditions and how they are discharged

Expect a condition requiring the full scheme to be submitted and approved before the use begins, installed and commissioned in accordance with the approved details before first use, and then maintained for the life of the development. Expect a noise limit expressed relative to the measured background at an identified position, and a restriction on changing the type of cooking without further approval.

That last condition is the one that catches bakeries which later add a fryer. The abatement designed for baking will not handle grease laden air, and the change is a breach of condition as well as a nuisance risk.

Discharge the condition with the commissioning report, not with the design intent. Authorities increasingly ask for a post installation test on site, and an environmental health officer who has stood in a neighbour's garden at 5am is the person deciding whether your scheme worked.

If you want to see which supporting documents your particular unit and operation are likely to need, enter the postcode on PlanScope and work through the site constraints first.

This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.