Commercial Kitchen Odour-Control Systems Guide

Commercial kitchen odour control normally uses a treatment train, not one magic filter. Grease and smoke particles should be reduced before gaseous odour treatment, then the cleaned air needs an appropriate discharge location. The correct combination depends on cooking type, airflow, contaminant load, available space, planning risk, pressure drop and maintenance capability.

Start by separating the problems

Kitchen exhaust can contain:

  • larger grease droplets;
  • fine grease and smoke particles;
  • water vapour;
  • heat;
  • gaseous and volatile odour compounds;
  • combustion products where fuels are burned.

One technology rarely handles all of these. A carbon filter designed for gaseous compounds can be rapidly compromised if it receives a heavy grease load. A particle collector may visibly clean smoke without removing all odour.

Stage 1: canopy grease filters

Grease filters at the canopy are the first defence. Their job is to separate grease before it reaches downstream ductwork and treatment equipment.

They need:

  • correct type and orientation;
  • airflow within their intended operating range;
  • safe removal and cleaning access;
  • a cleaning frequency based on use;
  • intact fit so air cannot bypass them.

Canopy filters reduce grease; they do not eliminate the need for duct cleaning or automatically provide odour control.

Stage 2: fine filtration or electrostatic precipitation

Fine mechanical filters or electrostatic precipitators (ESPs) can reduce smaller grease and smoke particles.

An ESP charges particles and collects them on plates. Potential advantages include effective fine-particle removal with a different pressure-drop profile from dense disposable filters. Performance still depends on correct sizing, electrical operation, cleaning and upstream grease management.

An ESP is primarily a particle-control stage. Reducing smoke and grease can protect later carbon or UV/ozone stages, but the ESP should not be described as complete odour removal by itself.

For a practical specialist explanation, see Extechnology's guide to combining ESP, activated carbon and ozone/UV-C.

Stage 3: activated carbon

Activated carbon adsorbs suitable gaseous compounds onto a large internal surface. In kitchen extract it is normally positioned after effective grease and particulate removal.

Important design factors include:

  • carbon type and mass;
  • air velocity and contact/residence time;
  • temperature and humidity;
  • contaminant mixture and concentration;
  • casing design and bypass prevention;
  • pressure drop;
  • safe access and replacement plan.

Carbon becomes exhausted. A box labelled “carbon filter” is not meaningful without media quantity, duty and a replacement strategy. Extechnology describes carbon as a downstream polishing stage in its commercial kitchen carbon-filter information.

UV-C and ozone-based treatment

Some systems use ultraviolet light to support photolysis/oxidation processes and may generate ozone to react with grease and odorous compounds within the extract path. Product configurations vary considerably.

The design should consider:

  • correct wavelength and output for the intended process;
  • residence time after treatment;
  • airflow and duct geometry;
  • lamp fouling and cleaning;
  • lamp ageing and replacement;
  • safe interlocking so the system only operates under intended airflow conditions;
  • materials compatibility;
  • residual ozone at discharge;
  • access that prevents unsafe exposure during maintenance.

Do not use the words “ozone” and “odour eliminated” as if they prove performance. The complete design and operating controls matter.

High-level discharge is part of odour control

Treatment reduces the contaminant load; dispersion reduces exposure at receptors. A well-positioned, unobstructed high-level discharge can be more robust than relying on increasingly complex filtration to compensate for a poor terminal location.

Local-authority expectations vary. Westminster's guidance is one example of a council strongly favouring full-height discharge and requiring site-specific justification for constrained alternatives.

Technologies should be selected from the cooking duty

The proposed menu and equipment determine the pollutants:

  • light baking/reheating may create heat, moisture and lower odour loads;
  • frying increases grease and odour;
  • chargrilling creates smoke, fine particulates and strong odour;
  • wok cooking can produce high thermal and particulate loads;
  • solid fuel adds combustion products and visible smoke considerations;
  • coffee roasting and bakery processes have different exhaust characteristics from a standard cookline.

Do not carry a filtration specification from one restaurant into another simply because the airflow is similar.

Maintenance is part of the design

Ask before purchase:

  • Who cleans each stage?
  • How often is inspection required?
  • Can filters, ESP cells and lamps be removed safely?
  • What access clearance is needed?
  • What happens to system pressure when filters load?
  • How will saturation or failure be detected?
  • Are spares and media available?
  • Who records the work for planning, fire and insurance purposes?
  • Can the kitchen continue operating safely during maintenance?

Extechnology's maintenance overview for ESP, carbon and UV-C gives an example of the component-specific thinking required.

Common specification mistakes

Selecting from a product brochure before assessing risk

The assessment should define the problem; the product then fits the duty.

Treating percentage claims as universal

Test conditions, pollutant, airflow, maintenance and measurement method affect performance. Request evidence relevant to the proposed application.

Ignoring system resistance

Every treatment stage affects fan selection and the operating point. Adding filters after commissioning can reduce actual airflow and undermine canopy capture.

No bypass control

Air that passes around filters or through poorly sealed casings is untreated regardless of media quality.

No safe access

Equipment that cannot be maintained will not retain its design performance.

Relying on odour control to solve noise

Fan and airflow noise need their own assessment and mitigation.

What to request from a supplier

  • design airflow and operating range;
  • pollutant/duty assumptions;
  • proposed treatment sequence;
  • pressure drop when clean and at defined loading conditions;
  • fan-duty implications;
  • space and service clearances;
  • electrical and controls requirements;
  • interlock and safety arrangements;
  • performance evidence and its test conditions;
  • consumables and expected maintenance tasks;
  • commissioning method;
  • warranty limitations;
  • maintenance cost and responsible party.

Put filtration inside the whole kitchen plan

The KIG 317 Commercial Kitchen Installation Guide helps project teams consider odour treatment alongside cooking duty, extract design, discharge, planning, maintenance and handover.

Sources and further reading

This is general technology guidance, not a product specification or promise of planning approval. A competent designer should select and size the complete system for the actual duty and local requirements. Last reviewed: 13 August 2026.