Ventilation and Extraction Statement

The specification depends on the type and intensity of cooking. A full restaurant kitchen typically requires a canopy extraction system with grease filters, a dedicated ductwork run to a high-level discharge point, odour abatement technology such as activated carbon filters or ESP units, and sufficient air replacement provision. The system should achieve a minimum of 30 air changes per hour in the kitchen and discharge at least 1 metre above the eaves of the building.

The discharge point must be high enough to allow adequate dispersion of cooking odours before they reach neighbouring properties, particularly residential windows. DEFRA guidance recommends discharging at least 1 metre above the ridge line of the building where possible. Low-level discharges into courtyards or near windows are likely to generate complaints and are rarely accepted by environmental health officers.

The main odour abatement technologies are activated carbon filters which adsorb odour molecules, electrostatic precipitators (ESPs) which remove grease and smoke particles, UV ozone systems which break down odour compounds, and combinations of these technologies. The appropriate level of treatment depends on the sensitivity of the location and the intensity of cooking. Premises cooking with charcoal or producing heavy frying odours typically require more aggressive odour control.

Noise from kitchen extraction systems is assessed using the methodology in BS4142:2014, which compares the rating level of the noise source (the extraction system) with the background sound level at the nearest noise-sensitive receptor. A rating level that exceeds the background by more than 5dB indicates a likely adverse impact, while a difference of more than 10dB is a strong indication of significant adverse impact. Anti-vibration mounts, acoustic attenuators, and fan selection are used to achieve compliance.

External ductwork is common but can be a contentious design issue, particularly in conservation areas, on listed buildings, or in prominent locations. The statement should address the visual impact with photographs or photomontages and propose mitigation such as colour-matched cladding, routing ductwork on less visible elevations, or concealing it within purpose-built enclosures. Some councils require ductwork to be entirely internal.

Regular maintenance is essential for the system to function effectively and comply with planning conditions. Grease filters should be cleaned weekly, carbon filters replaced every 6 to 12 months depending on cooking intensity, ductwork professionally cleaned at least annually, and fans serviced every 6 months. The statement should include a maintenance schedule, and planning conditions often require a maintenance log to be kept and made available for inspection.

DEFRA published guidance on the control of odour and noise from commercial kitchen exhaust systems which sets out a risk-based approach to specifying extraction equipment. It categorises premises by cooking type and proximity to sensitive receptors, from low risk (reheating food far from houses) to high risk (heavy frying or charcoal cooking near residential windows). Higher risk scenarios require more sophisticated odour and noise control measures.

Recirculating systems filter and return air to the kitchen rather than extracting it outside. They avoid the need for external ductwork and discharge points, making them attractive for premises where routing ductwork is impractical. However, many environmental health officers are sceptical about their effectiveness for anything other than light cooking, and they are unlikely to be accepted for premises involving heavy frying, charcoal grilling, or high-volume cooking.

Installing external ductwork and a discharge flue usually requires planning permission as it constitutes an alteration to the external appearance of the building. In some cases, it may be permitted development under Part 7 of the GPDO for industrial and commercial premises, but this does not apply in conservation areas or to listed buildings. A full planning application or Listed Building Consent will be needed in sensitive locations.

Engage with the council's environmental health team early to understand their requirements, specify a system that meets or exceeds DEFRA guidance for the risk category of your premises, position the discharge point as far from residential windows as possible and at high level, commit to a robust maintenance regime in the planning statement, and consider offering planning conditions that limit cooking methods or operating hours if the location is particularly sensitive.