Cubic feet per minute (CFM) measures the velocity of air flow in and out of a space to determine vent power. The CFM ratings offered by some manufacturers often have the certified ratings to HVI 916* Airflow Test Procedure or AHAM HRH-2-2019** Standards.
*Home Ventilation Institute (HVI)
**Association of Home Appliance Manufacturers
Home Ventilation Institute (HVI)
When a ventilation product is HVI certified, it means that the air flow (CFM rate) and noise level (sones) have been tested to perform as promised under the rated conditions. If your vent has been HVI certified, you can visit the HVI website (www.hvi.org) to understand how it will perform based on your desired type of installation (duct configuration and some speed settings).
Association of Home Appliance Manufacturers
Some ventilation products have received AHAM verification. This is important because it means that an unbiased verification of the product has been done with respect to the manufacturer’s air flow (CFM) and noise level (sones) under differing installation situations. If you're looking to see if a vent you're interested in purchasing has undergone AHAM Verified, please go to the AHAM website (www.aham.org). If verification has been performed on that particular vent product, you will be able to see the results.
Choosing the Right CFM
It is important to choose a properly sized ventilation unit with the right CFM level as not doing so could have consequences. A too-low CFM rating may not completely clear the air in your kitchen. On the other hand, choosing a ventilation system where the CFM rating is too high can create negative pressure in the space, which means that air will need to be replenished in some other way. Additionally if the CFM is too high, air can be removed from places where you may not want it to be removed from.
When you are determining the minimum CFM requirements you need to consider a number of factors including favourite cooking techniques. If you like to sear, blacken and fry or generally use 4 or more burners you may require a higher CFM rating to refresh the air. However, the higher the CFM the louder the hood will be. If you love to simmer and sauté or typically use 2 burners, you may require a lower CFM rating.