Closed room set ups???

Ive recently been looking into "closed room" set ups where there is no fresh air intakes. Am i understanding this correctly? Some people never have any fresh air coming in? I have seen some videos and people seem to grow without any problems this way. Can anyone shed some light for me if this is doable?

The set ups had a lot of fans, AC, and tons of money put into the, but they claimed to be "closed rooms"


So here's a link to one of the videos that i watched, the 1st 30sec describes what im talking about. Also if anyone knows anything about the "chiller" hes using, id like to know more about it.
http://www.urbangrower.com/UG_30_Medi_Grow.html

nobody has any info?

Need CO2 enrichment and climate controllers. Rooms like this often use a water cooled A/C unit because they require LOTS of cooling.