Commercial Kitchen Ventilation Design is often considered a subdiscipline of general commercial ventilation design. Exposure to commercial kitchen ventilation design may limited when compared to general ventilation design. Although the principles and physics are similar, there are some significant differences when designing for commercial kitchens. Principle among the differences are the focus on fire safety and the regulations assigned to them. Designing an efficient commercial kitchen ventilation system requires careful consideration of various factors. Here are some recommendations to follow:
Understanding local and national code requirements surrounding kitchen ventilation.
Familiarize yourself with local building codes and health department regulations related to kitchen ventilation. Compliance is crucial for safety and legal reasons. The codes and regulations that impact kitchen ventilation design are as follows:
- NFPA 96, National Fire Protection Association Standard 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations
- NFPA 17A, Standard for Wet Chemical Extinguishing Systems
- U.L. 300 Fire Testing of Fire Extinguishing System for the Protection of Commercial Cooking Equipment
- International Mechanical Code (IMC) Chapters 505, 506, 507, 508, 509
Calculation of Exhaust Airflow Requirements
- Determine the required exhaust airflow based on the size of the kitchen, type of cooking equipment, and cooking processes. Consider factors like heat load, smoke production, and contaminants.
- Many manufacturers of U.L. 710 listed exhaust hoods will provide exhaust air quantities required per application. Ensure the exhaust values take into account the exhaust necessary to remove the convective load generated by the appliances. U.L. listed minimum exhaust rates per cooking duty are not to be used for design exhaust airflow rates.
Use of Variable Speed Controls:
- ASHRAE 90.1 requires adopting one of 3 energy-saving measures for kitchen exhaust systems exceeding 5000 cfm. In some jurisdictions, this number has been lowered to 2500 cfm
- Use of an automatic variable volume control system 50% or greater transfer air
- Use of heat recovery system
- A variable volume control system is prevalent due to its availability from the manufacturer and ease of installation. A Demand Control Kitchen Ventilation system (DCKV) is available from the very basic to more sophisticated IoT platforms. The temperature measuring of the appliances of these devices use:
- RTD sensors (Resistance Temperature Detector)
- Thermal Imaging Sensors (measure surface temperature of the appliance and rate of change)
The DCV controls for exhaust fans send out a corresponding frequency signal to match the exhaust VFD for the make-up air systems. A more accurate method includes a proportional 0-10v output signal based on the measured exhaust. This allows for adjusting ventilation automatically and keeping the space in balance.
Look for the next articles where we will be covering
• Hood design and placement
• Capture Efficiency
Several important factors must be considered when designing a commercial kitchen ventilation system. It is advisable to contact experts who manufacture this kind of equipment and appliances, as they can guide you in making the proper selections to meet your requirements.
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