Holidays are often associated with family, friends and food.  Whether you are furiously working in the kitchen or anxiously awaiting mealtime, HVAC systems can play a major role during the holiday season.

Kitchen ventilation is achieved using range hoods.  Range exhaust hoods remove cooking byproducts such as heat and odors by filtering and exhausting them outside. 


Range exhaust hoods can be categorized by many different criteria. These can include:

  • Volumetric airflow
  • Fan motor types
  • Physical dimensions
  • Noise level

For the purpose of this blog, we will focus on the volumetric airflow and noise level.

Volumetric Airflow and Noise Level

The volumetric airflow is measured in CFM, cubic feet per minute.  The CFM achieved by the exhaust fan motor varies based on the pressure drop of the system.  The calculated pressure drop varies from system to system based on the ductwork length, bends in ductworks, backdraft dampers, etc.

The noise level is measured in sones or decibels.  The majority of noise produced by exhaust systems can be attributed to the fan motor and the air traveling through the ductwork.  Under sizing ductwork will produce more noise than correctly sized ductwork. The lower the number for sones or decibels, the quieter the system will be.

Due to the nature of a range hood, a pressure gradient is created.  A makeup air unit is needed to supply tempered air back into the space. It works by pulling in outside air, heating the air to a desired temperature, and distributing it to eliminate the pressure gradient.


Allegheny Design Services

Proper mechanical, electrical, and plumbing (MEP) design is critical for moving air, water and electricity to the areas they need to go.  Kitchens are no exception and can require intricate MEP design.

With the combination of BIM workflow and staff experience, we look forward to providing solutions to your next project.

To learn more about us and to see our recent projects, click here.

Thanks for reading and happy holidays!


Written by Alex Clarkson, EIT, Junior Mechanical Engineer

Alex-ClarksonAlex Clarkson joined the Allegheny Design Services team in March of 2015 as an engineering Intern. He graduated magna cum laude from West Virginia University with his bachelor’s degree in mechanical engineering in May 2015. While at WVU, Alex served as the treasurer of the student branch of ASHRAE during the fall 2014 semester and president during the spring 2015 semester. Prior to joining ADS, Alex worked as an MEP engineering Intern at Miller Engineering. He is now a junior mechanical engineer at ADS, primarily focusing on the design of mechanical and plumbing building systems.