heres some venting info
Step 1 – Room Volume
First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet.
Step 2 – CFM Required
The fan should be able to adequately exchange the air in a grow room once every three minutes. Therefore, 512 cubic feet/3 minutes = 171 cfm. This will be the absolute minimum cfm for exchanging the air in a grow room.
Step 3 – Additional factors
Unfortunately, the minimum cfm needed to ventilate a grow room is never quite that simple. Once the grower has calculated the minimum cfm required for their grow room the following additional factors need to be considered:
Number of HID lights – add 5% per air cooled light or 10-15% per non-air cooled light.
CO2 – add 5% for rooms with CO2 enrichment
Filters – if a carbon filter is to be used with the exhaust system then add 20%
Ambient temperature – for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%.
And some more if you need it
xxx.bghydro.com/BGH/static/articles/0706_vent2.asp
