From what I know, He is referring to a passive intake as not having any fan at all, while an active intake is one that has a fan that blows air into the area.

As for exhaust fans, many people seem to recommend the vortex blower fans, mainly because they are cost-effective to run and that you can use a variable speed control with them. The dayton blowers are good at exhausting air too, but at a much higher electrical consumption. (compare a 6" vortex blowing at 449 cfm's and running 80 watts, vs. a dayton 465 cfm blower that consumes 2.9 amps (120v x 2.9A=), or 348 watts.

This place has decent prices on the vortex:
Vortex 6 inch Inline Fan 449 CFM @ Businesslights.com
HTH