Heritage Building Hybrid Recirculation Kitchen Ventilation

How to Manage Kitchen Ventilation in Heritage Buildings or Buildings with Limited Infrastructure space.

What is “Hybrid Recirculation” Kitchen Ventilation?

It is a commercial kitchen ventilation system that incorporates recirculated air from an all-electric cooking process plus a conventional system serving gas/solid fuel-fired catering appliances carrying the need to discharge to the atmosphere.  This dual approach enables the catering operator to still have the option to include certain items of gas-fired equipment if that is the preference.

This hybrid approach is an ideal solution for those projects, such as the following Case Study, where there is an existing system discharging to the atmosphere, but the exhaust duct does not have the spare capacity to accommodate additional catering equipment.

A Hybrid Recirculation Kitchen Ventilation Case Study
Fortnum & Mason, London.

Key Points:

  1. The actual premises, previously a foodservice facility, within the Royal Exchange in London had an existing extract riser duct, too small for the new requirements.
  2. From a planning standpoint, absolutely no prospect of increasing the size of this duct nor for providing an additional duct.
  3. The decision was to offer a “hybrid” solution. Divide the cookline canopy into 3 sections;
    • UV-C canopy/exhaust hood over the gas-fired appliances
    • Cold water mist Canopy over the solid-fuel appliances
    • Filter Canopy over the electric appliances
  4. The existing riser duct, plus a new Pollution Control Unit, for the exhaust air from the gas-fired and solid-fuel cooking appliances, and an approved Recirculation Unit for the air coming from the electrically-powered cooking equipment.


  • English Heritage (Grade 1 Listed)…….delighted with solution.
  • Local Authorities (City of London)…….fully satisfied
  • M&E Design Consultants……relieved that a solution was found
  • End User (Fortnum & Mason)…..happy to sign long-term Service Contract

Hybrid Recirculation Kitchen Ventilation… continued

Classic 10% Bleed-Off Hybrid

  • 100% extract from the kitchen canopy through the Recirculation Unit
  • 10% of this “cleaned” air discharged to atmosphere (e.g. at low level if required)
  • The balance, i.e.90%, is supplied back into the kitchen
  • The remaining 10% is either ducted in as fresh air or, in the case of Shopping Malls, Food Courts, etc., enters the space as infiltration air

Typical Hybrid Kitchen Arrangement

Hybrid Recirculation Kitchen Ventilation Arrangement

Reasons To Opt For A Hybrid Recirculation Kitchen Ventilation System

  • The opportunity to increase a cookline or menu offering without costly upgrade of existing system
  • Development of new cooking areas such as Theatre cooking, Finishing kitchen, etc.
  • Ability to spread plant across the building, ease space in existing Plant Rooms
  • Reduce duct size to atmosphere
  • Energy saving….if cookline not in use 100% of the time…can be isolated
  • Reduction in Planning Application for kitchen upgrade
  • Recirc system can be client owned….not Landlord.  Can be relocated to the next site should lease not be renewed
  • Can enable work to be carried out outside normal operating hours without inconveniencing neighbours.
  • Facilitates cooklines in different fire zones
  • Enables kitchen upgrade without closing the establishment food offering

In all cases, the local authority should be consulted to ensure meeting all local codes and heritage building requirements.

Before selecting any hybrid recirculating kitchen ventilation systems, ensure you do your due diligence on requirements for installation based on the local authority having jurisdiction (AHJ). Some municipalities have specific needs or approvals beyond the products listing.

Should you require help in selecting a hybrid recirculating kitchen ventilation system, the experts that manufacture these types of units can guide you on the proper selection needed to meet your requirements.

Read another article relating to Recirculating or Ventless Solutions for Commercial Kitchen Ventilation – Advantages and Limitations of Ventless Solutions for Commercial Kitchen Ventilation or New Approaches For Recirculating Systems in Kitchen Ventilation

Subscribe today to kitchenventilation.com

Stay up to date by subscribing to Halton’s Commercial Kitchen Ventilation Blogs by entering your email address to subscribe and Halton will provide you with the latest information on commercial kitchen exhaust hoods, pollution control units, air handling, and safety systems. You will receive notifications of new posts by email.

Subscribe to blog via email

Enter your email address to subscribe to kitchenventilation.com and receive notifications or new posts by email.

%d bloggers like this: