Hiya,
I'm currently making my first grow box, its quite small, the dimensions are something like 0.5 x 0.8 x 1.2 meters, or 1.5 x 2.5 x 4 feet.
To ventilate the area im going to use 2x 120mm pc fans as a exhaust and passive intake, the fans can run at two speeds either 21.5 CFM or 36 CFM...