External ducts and plant may need planning permission even where the café or restaurant use is already lawful. A statement that equipment is “commercial grade” is not a substitute for a site-specific design. [1][2]
Begin with the menu and cooking equipment
The type and intensity of cooking affect the extraction required. Provide the ventilation designer with the proposed appliances, food processes, operating hours and likely level of use. Bromley's published guidance links odour assessment to the nature of the operation and the sensitivity of surrounding premises. [2]
The kitchen also needs an adequate air supply. HSE explains that cooking equipment can generate fumes, heat and combustion products, and that ventilation needs to remove contaminants and provide sufficient replacement air. Extracting air without considering its replacement is not a complete ventilation design. [3][4]
Establish where the duct can go
Survey the proposed route from the kitchen to the discharge point, including nearby windows, roof levels and neighbouring properties. Westminster's March 2021 guidance gives preference to appropriate high-level discharge and sets out a hierarchy for assessing other arrangements. It does not say that fitting a filter makes any low-level outlet acceptable. [1]
Show the route on plans and elevations before committing to a kitchen layout. A duct that cannot be accommodated acceptably on the outside of the building may require the kitchen design or operation to change. The planning question remains separate from the business's Class E status. [1]
Odour and noise are different assessments
Odour treatment needs to match the cooking process and exposure of surrounding occupiers. Noise assessment should consider the fan, airflow, vibration and the proposed hours, including the effect on residential windows. Solving one issue does not demonstrate that the other is resolved. [2][5]
The specification should identify the proposed equipment and treatment stages rather than promise an unspecified “odour-free” system. National noise guidance also recognises that equipment location, enclosure, building layout and operating restrictions can work together as mitigation. [2][5]
What an application should explain
The council's local validation requirements determine the submission, but a useful coordinated package includes the kitchen layout and equipment, duct and discharge drawings, an odour-control assessment, plant-noise information and the maintenance approach. State the intended operation consistently across these documents. [1][2]
For example, a report based on a lightly used café should not be relied on unchanged for an intensive takeaway kitchen. A later change to the operation may require the extraction assessment and relevant planning conditions to be revisited. [2][6]
Maintenance and fire precautions
Allow access for cleaning and servicing and specify who will maintain filters and other treatment equipment. Published council guidance treats maintenance as part of achieving continuing performance, not simply a matter for the equipment warranty. [2][1]
Coordinate the design with the premises' fire precautions and fire risk assessment. Building-control approval, planning approval for external plant and the operational fire risk assessment serve different purposes; none should be treated as a substitute for the others. [7][8]