• Adrienne Gould-Choquette, P.E.

How to use the Commercial Kitchen Exhaust Hood Calculator





This article demonstrates the use of the Commercial Kitchen Exhaust Hood Calculator.


You can access all calculators on the HVAC Calculators page or by the dropdown menu. The calculators are listed alphabetically by category.


There is a list of instructions at the top of the calculator and a note explaining that a separate analysis needs to be done for each hood. So let's get started.


This demonstration is based on a project I am currently working on. It is in the US, so we will select English Units. The client specified a Wall Mounted Canopy, so we will choose this from the dropdown list. If you hover over the dropdown list, there is a description/summary from ASHRAE of the differences between the hoods.


Let's call the Project Name Demonstration Kitchen and designate this exhaust hood as KEF-1. If you hover over the Hood Type dropdown list, there is a description of the hood types. Our application will be a Type I hood.


The client provided a kitchen layout with the following equipment under the hood:

  • 30" Range, hot top, gas

  • 36" Griddle, flat, gas

  • 48" Fryer, open deep-fat, gas


The equipment is listed alphabetically. Select the equipment type from the list and enter linear inches of equipment. To add another piece of equipment under the hood, check the "Other Equipment" box. Enter all of the equipment.


After the equipment has been entered, there is one more optional input. If the design also includes a Make-Up Air Unit, enter the percentage of Make-up air in the dropdown box in the Summary Table.


The summary table gives the linear feet of equipment and subsequent required linear feet of the hood. The Exhaust rate per the 2018 International Mechanical Code and the exhaust rate range per ASHRAE and their relevant make-up air volumes if applicable. Based on your inputs, there are also some notes from ASHRAE, the Florida Building Code, and the International Mechanical Code.


Back to the project, this is a small restaurant, and the most significant load is the outdoor air required to keep the building in balance. The restaurant owner decided to reconfigure the kitchen and switch to a Single Island Canopy. I advised my client that changing hoods would increase the required hood flow rate (and make-up air) from 3,150 CFM to 5,250 CFM and was not practical based on their restaurant's space constraints and budget.

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