Commercial kitchen extraction and the EMAQ guidance
Kitchen odour applications are judged against the EMAQ risk based approach. Here is how cooking type, flue termination height, discharge velocity and maintenance decide the outcome.
Commercial kitchen extraction guidance in England is dominated by one document: the EMAQ guidance on the control of odour and noise from commercial kitchen exhaust systems, published in 2018 for Defra and used by environmental health officers across the country. If your application involves cooking, the officer assessing it is working from that guidance, so write the submission to match its structure.
The guidance is risk based. It asks how much cooking you are doing, what kind of cooking it is, and how close the nearest sensitive receptor sits. Those three answers set the level of odour control the officer expects, and an application that states them plainly gets a far better reception than one that attaches a fan specification and hopes.
The risk based approach to kitchen odour
The assessment combines the scale of the kitchen, the odour potential of the cooking process and the separation distance to receptors, then reads across to a level of control. A small cafe toasting sandwiches 40 metres from the nearest flat sits at one end. A charcoal grill in a basement unit with flats directly above sits at the other.
Work through it honestly at the design stage rather than after the environmental health objection. The difference between a medium and a high risk classification is the difference between grease filtration with carbon and a full system with ultraviolet or ozone treatment ahead of carbon, and the capital cost difference is substantial.
State your classification in the submission and show the workings. An officer who can follow the reasoning will engage with it. An officer presented with a conclusion will run the assessment themselves and use their own assumptions.
Matching odour control to the cooking type
Odour potential varies with the process, not with the cuisine. Frying, chargrilling, roasting meat and cooking fish generate more odour than boiling, steaming and baking bread. A menu that changes seasonally should be assessed on its worst case, because the extract system cannot be upgraded when the grill arrives.
A typical treatment train runs in stages.
- Grease filters at the canopy, usually baffle type, to remove particulate and grease.
- Secondary filtration such as bag or panel filters where the loading is high.
- Electrostatic precipitation or ultraviolet and ozone treatment to break down odorous compounds.
- Activated carbon as the final polishing stage.
- Odour neutralising additives, which the guidance treats as a supplement rather than a substitute.
Two points worth knowing. Carbon has a finite life that depends on the loading, so the system needs a replacement schedule rather than an installation date. And ozone systems need a contact chamber of adequate length and a safe residual ozone strategy, so a short duct run with an ozone lamp bolted in does not deliver what the manufacturer's data sheet claims.
Flue termination height above eaves and openings
Flue height is the parameter officers focus on, because it decides whether odour disperses or drops into someone's bedroom.
The conventional requirement is termination at a height above the roof of the host building and of nearby buildings, commonly expressed as at least a metre above the ridge, clear of any openable window, balcony, roof terrace or air intake within a stated radius. Check the EMAQ guidance and your authority's own supplementary guidance for the figures they apply, because the radius in particular varies.
Discharge must be vertical and unimpeded. A flat plate rain cap or a Chinese hat cowl deflects the plume sideways and defeats the height you paid for, so specify a conical or open termination with a drain instead.
Height also drives the planning issue. A flue running up the rear elevation of a listed building or a building in a conservation area is an external alteration with its own consent requirements, and on a four storey building it is a design problem as well as an engineering one. Draw it on the elevations early.
Discharge velocity and why it matters
Velocity does the work that height cannot. A plume leaving at a low speed hangs around the building and gets pulled back into the wake. A plume leaving quickly punches clear of it.
Guidance in this area commonly sets a minimum efflux velocity in the region of 10 metres per second at the point of discharge, measured with the system in its normal operating condition. State the design velocity in the submission, along with the duct diameter and the fan curve that delivers it.
Two practical traps. Velocity falls as filters load, so the figure quoted for a clean system is optimistic by the time the carbon is halfway through its life. And variable speed drives set to run at low speed overnight can drop the velocity below the design figure at exactly the time neighbours notice.
Noise from the extract fan
Odour and noise are assessed together, which is why the EMAQ guidance covers both. The relevant method for plant noise is BS 4142, which compares a rating level, adjusted for character features such as tonality and intermittency, against the measured background sound level.
Mitigation is routine and should be designed in rather than added later: attenuators on the supply and extract, anti-vibration mounts, flexible connections, an acoustic enclosure or louvre where the fan is external, and duct lagging where the run passes a habitable room. A Noise Impact Assessment prepared by a suitably qualified acoustician is what councils expect, and professional review is strongly advised before it is submitted.
Deliveries, refuse collection and plant running outside trading hours often generate more complaints than the extract itself, which we have looked at in our note on night deliveries and servicing noise.
Maintenance regimes and conditions
Expect a condition requiring the approved extraction scheme to be installed and operating before the use starts, and a second condition requiring it to be maintained in accordance with a schedule.
A credible maintenance schedule covers grease filter cleaning frequency, carbon replacement intervals with a stated basis, ductwork cleaning to a recognised standard for internal cleanliness of ventilation systems, fan and attenuator inspection, and a written log kept on the premises and available to the authority on request. Offer that schedule with the application. Councils are more comfortable approving a system they believe will still work in year three.
A permission does not immunise you against complaints either. Odour and noise can amount to a statutory nuisance under Part III of the Environmental Protection Act 1990, a point covered in our note on statutory nuisance after permission is granted.
What to submit with the application
| Document | What it should contain |
|---|---|
| Extraction scheme | Canopy, filtration stages, duct route, fan, attenuation, termination |
| Elevation drawings | The flue drawn on every affected elevation with heights dimensioned |
| Risk assessment | Kitchen scale, cooking type, receptor distances, resulting control level |
| Equipment data | Manufacturer data for each stage, with design airflow and efflux velocity |
| Noise assessment | BS 4142 assessment with background measurements and rating level |
| Maintenance schedule | Cleaning and replacement intervals with responsibility named |
A Ventilation and Extraction Statement pulls those threads into one document, and where the officer asks for a fuller odour case an Odour Assessment is the next step up. Both should be reviewed by a suitably qualified specialist before submission. For specialist technical reports, qualified professional input may be required.
Illustrative example. A unit in a parade with flats above proposes a grill led menu. The first scheme shows grease filters, a short duct and a cowled termination at first floor level. Environmental health objects. The revised scheme adds ultraviolet and carbon stages, runs the duct to a metre above the ridge with an open termination, designs for a 10 metre per second efflux velocity and includes a maintenance log. Permission is granted with two conditions. The example is illustrative.
This is general guidance rather than legal advice. 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.
Frequently asked questions
What is the EMAQ guidance?
It is the guidance on the control of odour and noise from commercial kitchen exhaust systems published in 2018 for Defra, and it is the document most environmental health officers work from when assessing a planning application involving cooking. It sets out a risk based method linking kitchen scale, cooking type and receptor proximity to a level of odour control.
How high does a kitchen extract flue need to be?
Conventionally it terminates above the roof of the host building and nearby buildings, commonly expressed as at least a metre above the ridge and clear of openable windows, balconies and air intakes within a stated radius. The radius varies between authorities, so check the guidance and any local supplementary document before fixing the design.
Why does discharge velocity matter?
A slow plume is drawn back into the building wake and lingers around windows, while a fast plume clears it. Guidance commonly sets a minimum efflux velocity around 10 metres per second at the point of discharge. Velocity falls as filters load, so state the design figure and the fan curve that sustains it in normal operation.
Can I use a rain cowl on the flue termination?
Not a flat plate or conical cap that deflects the plume sideways, because it undoes the benefit of the flue height. Specify an open or low resistance termination with a drain instead. This is one of the most common reasons an otherwise acceptable extraction scheme is asked to be amended by environmental health.
What odour control does a chargrill need?
Chargrilling sits at the high odour potential end of the assessment, so expect grease filtration at the canopy, secondary filtration, ultraviolet or ozone treatment and activated carbon as a final stage. The exact requirement depends on kitchen scale and receptor distance, and the classification should be set out with its workings in the submission.
What conditions are normally imposed?
A condition requiring the approved extraction scheme to be installed and operating before the use starts, and a second requiring it to be maintained in accordance with an approved schedule. Offering a credible maintenance schedule with the application, covering filter cleaning, carbon replacement and duct cleaning intervals, makes approval considerably more likely.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.