Stirling Council Environmental Health
Cooking Smells - Advice to Food Businesses
In order to minimise nuisance to nearby properties, adequate extract ventilation needs to be provided
at all premises where hot food is prepared (i.e. cooked, reheated, baked etc.). The extent of the
requirement will depend on the location of the premises and the nature of the operation.
Cooker Hood/Canopy
All premises where hot food is prepared will require direct extract ventilation above any source of
fumes likely to cause smell nuisance e.g. in a kitchen this will mean a canopy or hood above all
cookers, fryers and boilers. This should overhang the plan area of the appliance by 250 - 300mm for
island canopies and for wall mounted canopies the overhang should be 250mm at the front and
150mm at the ends.
Grease Filters
Larger premises and premises where a substantial portion of the menu involves frying will need
grease filters in the canopy. These reduce the smells associated with frying and prevent grease buildup in the ducting. They must be cleaned regularly - ideally weekly, and this can be carried out "in
house", or if carried out by removal of filters from the premises then there must be
replacement/temporary filters available.
Odour Control
Premises preparing strong smelling and spicy foods or where there are problems with the local
topography, are likely to require the installation of some form of odour control. The following methods
are available.
Activated Charcoal Filters
These are installed in the extract duct and filter out most of the cooking smell. They are
usually disposable and will last for 6 months to a year depending on their use. It is essential
that they are of adequate size for the volume and type of odour. Their life and effectiveness is
increased by the installation of a pre cooler and a fabric filter.
Air Dilution
This method involves diluting the fumes with fresh air. The discharge of the resultant mixture
is fan assisted hence it is at an increased velocity. Although the final effluent its self may smell
less strong, the net quantity of odour producing gasses remains the same so this method is
only likely to be effective where the problem arises from smells trapped in an enclosed area by
e.g. high buildings where the extra velocity will allow it to discharge at a higher point. Care
must be taken to ensure this will not just move the problem to another location.
Odour Neutralisation
This method works by spraying an odour neutralising chemical into the air stream of the
effluent. This can be very expensive and may not always be effective.
Point of Discharge of Extract Outlet Duct
The point at which the outlet of the extract system discharges will depend on the local topography and
the proximity of nearby commercial and residential property. Each situation will be different so each
application must be considered on its own merits. The general principle is that extract ducts should
discharge fumes as high as possible into the atmosphere and well above the highest windows of all
surrounding buildings - ideally 3 metres, but at least 1 metre and typically at a discharge velocity of
about 15m/s. Consideration will also require to be given to any loss of amenity at roof gardens/drying
areas etc. Two examples are:
Where the premises are located in a single storey building well away from other buildings, a discharge
at ground floor level (minimum 3 metres from ground level) may be acceptable.
-2Where the premises are located on the ground floor of a building with flats/offices in different
occupancy above, all extract ventilation from the premises must be channelled to a duct running the
full height of the building and discharging above and well away from the highest window of that
building or of surrounding buildings. In such cases this should be the sole point of discharge i.e. there
should not be any other extract fans in windows discharging fumes at other levels.
Discharging of fumes into courtyard wells and partially enclosed areas is not encouraged.
Discharge near horizontal surfaces
Discharge points above or near flat roofs will usually require to be raised above the level of the roof to
ensure dispersal of fumes. One metre should suffice providing there are no other considerations.
Performance of Extract System
Problems can often arise (especially during the summer in premises below flats/offices) where the
extract ventilation is not of sufficient size to providing adequate ventilation at all times and where staff
are tempted to open external doors and windows thus discharging fumes at ground level. The extract
ventilation system must therefore be capable of providing all of the ventilation requirements of the
kitchen/bakery area even in the heat of the summer.
The extract system should be powerful enough such that air flows in one direction into the kitchen and
out through the discharge outlet (i.e. negative pressure) so preventing escape of cooking odours. The
incoming air (i.e. the “make up” air) may be from a suitable area (e.g. not from an area where smoking
is allowed) or from the outside via screened grilles.
Transmission of Smells Through the Fabric of the Building
Steps must be taken to prevent the migration of cooking smells through the fabric of the building to
properties in separate occupancy. Properties on either side and especially properties directly above
can be affected. All breaks in the walls and ceiling in the kitchen/bakery e.g. where pipes, ducts and
wires pass through must therefore be made good and any porous materials e.g. new plaster likely to
permit the transmission of fumes must be sealed. Where strong smelling and spicy foods are
prepared, it may be necessary to also seal the public area of the business e.g. the restaurant or front
shop. Wire hung suspended tile type ceilings will not present a sufficient barrier to fumes if the original
ceiling above is damaged.
Ongoing Maintenance
Extract ventilation systems will only be effective if properly maintained. Where problems have occurred
or where, due to the location of the premises and the nature of the operation, there are grounds for
anticipating problems unless the system is operating at maximum efficiency all of the times, the
proprietor may be required to provide confirmation of a maintenance contract for the plant with a
reputable firm of ventilation engineers.
Noise
The extract system should be installed in such a way as to avoid nuisance to nearby properties from
fans. Where necessary, insulation and acoustic baffles may be required.
Hours of Business
In determining the suitability of any proposal, consideration will be given to the hours of operation of
the business e.g. late hours caterers operating only in the evenings are less likely to be a nuisance to
office premises but more likely to be a nuisance to residential premises.
Safety
The ventilation has to provide sufficient air for complete combustion and to dilute and remove
combustion products of burning appliances. Advice on this should be obtained from a competent
ventilation engineer.
H:\WDDATA\FOODVET\FORMS\ODOUR.DOC
Permissions
The following permissions will be required:Building Control - most alterations to a building including the installation of an external duct, require
building warrant.
For advice phone 01786 443322 and ask to speak to a Building Control Officer.
Environmental Health - the Planning Department and the Licensing Board usually act on advice from
this department as to the adequacy of the design of any proposed extract ventilation system. Any
advice given will be based on the criteria outlined in this leaflet.
It is best to consult Environmental Health of your proposals regarding new/altered food premises at an
early stage.
For advice, phone 01786 443322 and ask to speak to an Environmental Health Officer in the Food
Section.
Licensing Board - if it is intended to sell alcohol on the premises, an application should be made for a
licence. Before granting a licence, the Board will require confirmation that all necessary permissions
listed here have been received.
For advice phone 01786 443322 and ask to speak to the Licensing Officer.
Planning - most changes of use of a premise e.g.
permission.
from retail to catering will require planning
Stirling Council's planning policy permits food preparation businesses where they would not be
detrimental to the occupiers of adjacent properties by virtue of noise, disturbance or smell, but has a
general presumption against the siting of such establishments below flats/offices in separate
occupation unless environmental criteria can be satisfied.
External alterations to a building e.g. the installation of an external ventilation duct will also require
planning permission. The application should include the following:-
an elevation detail drawing of the proposed outlet for the system
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confirmation by a reputable firm of ventilation engineers that the proposed system is
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capable of meeting all of the requirements specified above, in particular with regard to size.
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details of the type of food preparation proposed
Where a proposed ventilation system has been designed for a specific use e.g. for a tea room where
no cooking takes place, then a restriction shall be placed on any planning permission given restricting
the use of the premises to that purpose.
If the building is listed as being of historical or architectural merit, internal alterations may require listed
building consent. The Planning office can advise as to whether or not the building has been listed.
For advice phone 01786 443322 and ask to speak to a Planning Officer.
Owner/s of the Building - if a duct requires to be fixed to other people's property e.g. a tenement with
several owners, then their individual permission must be obtained.