Odour Risk Assessments for Commercial Kitchens

Introduction

This post is intended for people who are seeking planning permission for a restaurant, takeaway, or other commercial kitchen and require advice on odour. The post sets out:

• Why odour assessments for restaurant and takeaway are often requested;
• The most odorous cuisines-types and cooking methods;
• The various techniques and technologies that can be used to minimise or negate odour risk.
• How Greenavon can help you get planning permission.

Why commercial kitchen odour risk assessments are required?

The requirement for odour risk assessments for proposed restaurants and takeaways comes from two different legal avenues; national and local planning policy, and the ‘Nuisance Provisions’ of the 1990 Environment Act.

The ‘Nuisance Provisions’ seek to protect people from what is defined as a ‘statutory nuisance’. The cause of a statutory nuisance is not limited to odours and a statutory nuisance can be caused by dirt, smoke, excessive noise, fumes, animals etc. However, to be defined as a statutory nuisance it must “unreasonably and substantially interfere with the use or enjoyment of a home or other premises” and generally be emitted by a business. Commercial kitchens are a more significant source of odour than residential kitchens and therefore have an increased potential for causing annoyance to neighbours. As such at planning stages, local authorities often require evidence that a proposal would not cause nuisance to nearby residents.

The bar for ‘statutory nuisance’ is fairly high for odour as it is difficult to prove; as such, many local authorities have specific planning policies in their Local Plans to protect residents from a loss of amenity caused by odour, fumes and noise etc. For example, Brentwood Borough Council’s Local Plan includes Policy PC06 [3] which states that non-retail development should “not give rise to a detrimental effect, individually or cumulatively, on the character or amenity of the area through smell, litter, noise or traffic problems”. As such, in order to comply with the relevant Local Plan, developers are often required to prove their proposal includes sufficient mitigation.

Which cuisines tend to be the most odorous?

Odours in cooking smells are made of three main constituent parts: grease, smoke and volatile gases. Cuisines with high grease and smoke emissions tend to be the most odorous and these are common in restaurants which use deep fat friers and grills, or use solid fuels such as charcoal (e.g. burger restaurants and kebab shops).

EMAQ+ guidance on the Control of Odour and Noise from Commercial Kitchen Exhaust Systems, a successor to Defra’s 2005 now withdrawn guidance of the same name provides a summary of cuisines and their odour potential. Fast food burger chains, fish and chip shops, and kebab shops are considered the most odorous with italian, french, pizza restaurants (that do not use charcoal) amongst the lowest. Pubs and cafes that simply re-heat food also have a low potential for odours release.

What are the common types of odour abatement technologies for commercial kitchens?

• Electro Static Precipitators (ESP)

Electrostatic precipitators work by removing grease and smoke from the kitchen extract air-stream. ESP’s charge the air-stream causing particles (grease and smoke) to be attracted to their oppositely charged plates, where they are collected. It is important for ESPs to have an associated grease sump, where grease can be collected and easily removed. It is strongly recommended that the grease sump is removed from the airstream itself to maintain ESP efficiency and minimise the risk of the ESP short-circuiting (due to grease build up). Further details on ESPs can be found in this blog.

• Carbon Filters

Carbon filters consist of activated carbon plates and should be installed post ESP as grease particles quickly clog the filters, rendering them inefficient. When working normally, odorous compounds passes through the activated carbon mesh and ‘adsorb’ onto the surface and are thereby removed. The more plates, the higher the level of abatement. It should be noted that carbon filters become less efficient over time and require replacing from time to time (usually an annual to bi-annual replacement dependent on the cooking type).

• Ultra violet/ Ozone generator

Ozone is a gas which when combined with other compounds can cause a reaction, changing its chemical makeup. In this way, ozone breaks down odorous chemicals in the air stream, reducing the odour effect. Generally, ozone generating systems use ultra-violet light to produce ozone.

• Odour neutraliser

Odour neutralisers can release a mist of bleach like compounds into the air stream to neutralise any odours. These are often used when the risk of odour is low.

What odour mitigation might be most appropriate for your commercial kitchen?

The choice of odour mitigation is complex, and site specific factors must be taken into account. When space is limited, an ESP followed by carbon filtration can provide a compact means to minimise both grease and gaseous emissions. This is a often a default solution in many commercial kitchens; however, it should be noted that if your proposed cooking method involves chargrilling, a “double-pass” ESP system would likely be required to remove the volume of smoke.

Ozone requires circa 2 seconds to break down odouous compounds in the extract and, therefore, one must ensure that there is sufficient duct length after the ozone generator to allow for the chemical reactions to occur. Ozone itself is a pollutant that is damaging to human health and the environment and generally, these units are not recommended for low-level releases, where excess ozone might discharge into areas where members of the public might be exposed.

It is becoming increasingly common for ESPs to be installed outside due to space constraints and therefore, it is essential that the unit purchased is weatherproof. An IP rating of less than 65 means that the unit might not have sufficient weatherproofing and that could lead to it being damaged in adverse weather conditions.

Whilst the treatment of air with some form of measure to minimise grease and odorous gases is essential, where and how the extract air is released to the atmosphere is also of great importance. Even if treated air is released into an area where it can’t escape easily (e.g. an enclosed courtyard) there will be a build-up of residual odours, which could have the potential to cause nuisance. As such, it is strongly recommended that any extract air is released vertically and at height, away from noses. The design of the discharge point is also very important in promoting the effective dispersion of point.

Some councils object, in principle, to the low level release of kitchen extract air, even after exhaust air is treated via the methods listed above. This can place developers in tricky situations as often design constraints do not allow for outside ducting to go to roof level (e.g. in a conservation area). Air Filtration Experts such as Purified Air can provide bespoke solutions in this case, Purified Air offer a system (the Reflow) whereby kitchen air is not extracted to the atmosphere but recirculated in the kitchen, after passing through several increasingly fine grades of filters.

How can Greenavon support you with a commercial kitchen odour assessment?

Greenavon has significant experience of providing advice to help people get planning permission for commercial kitchens. We work closely with air ventilation specialists to recommend solutions that are bespoke and cost-effective. For a free consultation, please do not hesitate to get in touch.