CFM
CFM
CFM
Calculating the necessary airflow is a critical step when designing and maintaining an HVAC
system or other air-moving application. The minimum airflow is the minimum amount of ventilation
required to maintain a comfortable and healthy indoor environment with good air quality.
Airflow is often measured in CFM, or cubic feet per minute. CFM is the volume of air that is
moved by or flows through a ventilation system.
You can calculate how much airflow you need in CFM by following a few easy steps.
The first step is to measure the volume of space that needs to be ventilated. Larger spaces
require more airflow and ventilation than smaller ones.
Start by using a tape measure to measure the length, width, and ceiling height of the space. It
will be easiest if all of your measurements are in feet. You can round to the nearest whole foot
if you are between full foot measurements.
You can use a length converter to convert your measurements to feet if needed.
The next step is to use the measurements from above to calculate the volume of the space. In
order to calculate the amount of airflow in CFM, you’ll need to calculate the volume in cubic
feet.
To do this, you can use the volume formula:
An important consideration when figuring the minimum airflow in CFM is how many air changes per
hour (ACH) are needed in the space. A kitchen in a restaurant will need many more air changes
per hour than a closet in a residence will need.
The air changes needed will multiply how many cubic feet per minute of airflow are required to
adequately ventilate the space. Changing the air in a space more frequently improves the air
quality.
To calculate the CFM needed to ventilate a space with a single air change per hour, you can use the following formula:
So, the cubic feet per minute of airflow needed to ventilate a space with a single air change per hour is equal to the volume of the space in cubic feet divided by 60.