Enter the actual airflow, standard airflow, actual power input, and standard power input into the calculator to determine the Fan Energy Index.

Fan Energy Index Formula

The following formula is used to calculate the Fan Energy Index (FEI). 

FEI = (Q_actual / Q_standard) / (P_actual / P_standard)

Variables:

  • FEI is the Fan Energy Index
  • Q_actual is the actual airflow delivered by the fan (cubic feet per minute)
  • Q_standard is the standard airflow for the fan type (cubic feet per minute)
  • P_actual is the actual power input to the fan (watts)
  • P_standard is the standard power input for the fan type (watts)

To calculate the Fan Energy Index, divide the actual airflow delivered by the fan by the standard airflow for the fan type. Then divide the actual power input to the fan by the standard power input for the fan type. Finally, divide the first result by the second result to get the Fan Energy Index.

What is a Fan Energy Index?

The Fan Energy Index (FEI) is a metric that measures the energy efficiency of fans. It is calculated by comparing the energy consumption of a fan to a baseline energy consumption. The higher the FEI, the more energy-efficient the fan is. This index was developed by the Air Movement and Control Association (AMCA) and is used to comply with energy efficiency regulations and standards.

How to Calculate Fan Energy Index?

The following steps outline how to calculate the Fan Energy Index (FEI).

  1. First, determine the actual airflow delivered by the fan (Q_actual) in cubic feet per minute (CFM).
  2. Next, determine the standard airflow for the fan type (Q_standard) in cubic feet per minute (CFM).
  3. Next, determine the actual power input to the fan (P_actual) in watts (W).
  4. Finally, determine the standard power input for the fan type (P_standard) in watts (W).
  5. After gathering the necessary variables, use the formula FEI = (Q_actual / Q_standard) / (P_actual / P_standard) to calculate the Fan Energy Index.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Q_actual = 500 CFM

Q_standard = 600 CFM

P_actual = 1000 W

P_standard = 800 W