I’m going to be running a couple fans. One is for light cooling, and the other will be for a scrubber. The idea is to exhaust unwanted heat from lighting outdoors during warmer months when central a/c is required, and exhaust the heat from lighting inside the house during the colder months to help offset heating costs.
At the moment the plan is to have the carbon scrubber exhaust indoors exclusively and only run when CO2 is off. I may end up using a 2 speed fan on the scrubber to keep the grow room(s) under a slight negative pressure even when the CO2 is being used.