Fan rating system

Is there a system with an equation, something like a CFM to power usage to speed to DbA ratio that, when calculated, would give you the most bang at the quietest, power stingiest level?

A rough one could be formulated, but it would be quite rough... Maximum and minimum values would have to be deciphered for each variable and then these values would have to be normalized so that they were all equal, but also weighted appropriately.

To answer your question, no, there is no system.

The one I'm looking to get isn't there. I'm looking to get this one:

http://www.svc.com/en92vasphipe.html

any input on this?