In my opinion, IF you are going to use cool tubes or air cooled hoods, then you need to duct air from outside of the grow area into the light and exhaust the air through a duct to outside of the grow area. That way you are avoiding adding heat to the room in th efirst place and presumably using cooler air to cool the lights than if you are pulling hot air from within the grow area.
Then you need to have a nearly constant air flow into the grow area of fresh air and stale air out of the grow area. If you are growing in an occupied building, the combination of those methods should keep the air temps inside of the grow area within limits. Personally I run a 6" fan 24/7 drawing air into the flower room through a 14" x 7" louvered vent from the living area in the lower level of my split level home and exhausting into the veg room which is then exhausted back into the house with a 20" square box fan set on low and my temps stay within 75F to 85F depending upon how many lights I'm running and what time of year it is. That way I recycle the heat into the house and in the summer get rid of the heat through the large central air conditioner and no one suspects anything from outside of the house.
My next move will be to add odor control to the air returning to the living area.
Great smoking.
