In reality, this "bigger is better" rule of thumb is incorporated into nearly every construction project, and usually the expected benefit of this implementation becomes a recurring problem, becoming evident just as the warranty expires on the project. More often than not, the problem is falsely identified as a control system problem.
To size the VAV box, the volume of cold air (typically 55 degrees F) required for maintaining a comfortable space temperature at the expected maximum load condition must be calculated. This resultant value obtained by this volume calculation is expressed in cfm.