What I mean by power is what's the total wattage of bulbs being lit in your area, dehumidifier being used, co2 burner being used, ballast located inside of the room. You have to add these up in order to know how much cooling you need. The rule i use of 6,000 btu per non vented 1000w bulb, 3,000 per vented 1000w bulb, that's just to cool lighting, I would add another 3,000btu cooling for a dehumidifier and another 1,000 btu per ballast if they are magnetic and located inside of the room, I add 1,000btu per burner in my co2 generator(8 burner co2 generator i would consider 8,000 btu to cool while it runs). I'll add those all up then times it by 1.1 to size be amount of air conditioning I need to cool it all. I give it 10% because filters get dirty and sometimes your ac might not be running 100% efficient. For example one of my flower rooms is 6 - 1000w non vented lights, with an 8 burner generator and 2 70 pint dehumidifiers and 6 magnetic ballast located inside of the room. That rooms requires right around 60,000btu of cooling which is 5 tons. @ 60,000btu I can get it down to 76degrees if needed but run at 80-81.
