efficiency of long-distance air plenums?

 

Now let us suppose that we have a cheap source of rotating-shaft power
in location A.

And let it be further posited that we need fresh-air ventilation at
location B.

At which distance does it stop being most efficient, to setup a fan at
location A, and just run a plenum?

Seek design equations and/or rules-of-thumb to help in decision making