Rossendale Borough Council

Ventilation systems - technical guide

Ventilation - guidance to food businesses

This guidance explains the council's requirements for new ventilation systems installed to cope with odour, fumes and noise from catering premises. It aims to ensure that proposed developments have adequate ventilation systems that will not lead to complaints from neighbouring properties about cooking smells or noise from equipment such as fan motors.

The council has powers under the Environmental Protection Act 1990 to take action against restaurants, takeaways and other food and drink premises if they cause a nuisance. However, it is much better for the relevant details to be incorporated into planning applications to ensure that such problems are unlikely to occur.

How to use this guidance

This guidance explains the key elements of a good extraction and ventilation system in all types of premises where hot food is prepared and describes the things the council will be looking for and why. If you are planning new catering premises and you have an architect or agent, you may wish ask them to study this guide so that the necessary details can be built into your plans.


Elements to control odour

The extract ventilation system must deal with cooking smells, fumes and steam produced by cooking and be designed to prevent or minimise any nuisance caused to neighbours.

There are several elements that a satisfactory extract system will include:

  • A canopy, which should extend beyond the cooking equipment area by at least 225mm, must be provided to collect the cooking fumes and direct them into the ductwork. Metal canopies are best constructed of stainless steel. Grease filters should be incorporated into the cooker hood and should be easily removable for regular cleaning before they become clogged.
  • The ducting should be as straight and short as possible to ensure that fumes are discharged as effectively as possible. Care should be taken when designing the route of ducting to avoid proximity to residential or office windows on neighbouring properties, which could give rise to complaint. The duct material (usually galvanised steel) should have a smooth internal surface and its route out of the building should avoid sharp bends. Circular ducting is preferred, as it maximises the flow rate.
  • There will be a fan positioned within the ductwork to pull cooking fumes from the cooker hood to the point of discharge. To aid good dispersion of cooking fumes, the size of the fan motor must be adequate to ensure proper ventilation. As a minimum, the efflux velocity should be 8m/s to a maximum of 15m/s.
  • Final discharge should be vertically upwards and should terminate at least 1m above the eaves. If there are buildings nearby which are likely to have an effect on the dispersion and dilution of odour, the flue should terminate at least 1m above the eaves of that building. Ground level or low level discharges should generally be avoided. However, where high level fume dispersion is not appropriate, a suitably enhanced scheme of ventilation is required. The discharge should be unimpeded by flue terminals, although some terminations, such as accelerator cones and sleeves may be accepted.
  • Carbon filters are also required and are essential when cooking fried foods and/or foods with strong odours.
  • Carbon filters should be fitted in the ductwork after the grease filters and before the fan and should be easily accessed for cleaning. The carbon filter should include pre-filters, as these ensure that no grease enters the carbon filters.
  • Access to all parts of the system is essential to allow routine cleaning of the system and maintenance of the filters.

Elements to control noise

Ventilation equipment must be designed and installed to avoid noise or vibration nuisance to neighbours. There are several methods that a satisfactory extract system will use to control noise:

  • The fan and motor should be sited within the building's structure to minimise outdoor noise. The fan and motor unit should be fixed on anti-vibration mounts and be joined to ductwork using flexible couplings to prevent the transmission of vibrations either to the structure or along the ducting. The fan and motor unit should not be fitted on to walls or ceilings adjoining residential premises.
  • Noise from the ventilation and extraction systems should be kept as low as possible and should not be audible within nearby residential properties when the fan and motor unit are in operation. As a rough guide, if you cannot hear the fan or motor noise just outside the residential property, the noise should not be audible within it either.
  • The extract ducting should be rigid in construction and installed with anti-vibration mountings. Large section ducts may need bracing or stiffeners to prevent drumming.
  • Noise attenuators may be required if the fan is noisy.


If you are in any doubt as to whether the noise from extract ventilation equipment complies with this guidance, you should seek advice from an acoustic consultant. A list of members of the Institute of Acoustics can be found at www.ioa.org.uk/.

Further information

Guidance from the Department for Environment, Food and Rural Affairs (Defra) on the control of odour and noise from commercial kitchen exhaust systems, February 2005.

Telephone: 01706 252565

Environmental Health Team, The Business Centre, Bacup, Rossendale, Lancs, OL13 0BB