A closed environment is going to cost significantly more than a vented system. Consider the cost of buying and running an AC and Dehumidifier, and running Co2 becomes a necessity since there will be no way for the air to be exchanged. A happy medium can be accomplished with the use of a tent, just hook the lower ducts to filters and vent the air out of the top of the tent through an inline fan & filter. I'm guessing you will air cool your light, since this will save you from heat issues. That is just my $.02