The benchmark is 50 watts per square foot of grow area.
I finally got motivated tonight and decided to figure out my square footage in the closet i am using. Its just 2 - 2 bulb shop lights leaned from the floor onto a ledge 32" tall. They are on like a 30 degree angle measured length wise across the floor is 38". The width of the 2 shop lights plus the reflector that closes it in is 16".

So if ya figure 38" long x 32" tall X 16" wide i came up with 11.33 cubic feet. Then that number started looking really big to me and i thought about it and finally figured out that i didnt take into account the 30 degree light slope. 11.33 cu ft is the total footage of a square box that size not a triangular one. So i sketched out a pic of it(when i was in school i never figured drafting class would come in handy but i must say i was wrong) and I figure that i have at least 1/2 less cu ft because of the angle of the light. Then i came up with 5.25 cu ft that sounds alot better to me. If the above quote is correct then I should need 280 watts to reach the bench mark. Right now i have 4 - 4 foot fluor tubes at 40 watts each and a dual cfl with reflector with 2 - 25 watt bulbs for a total of 210 watts. So i am about 70 short. I am gonna try to get one more dual cfl and finish the crop with that and see what my yield is. Now that you can understand what i am growing in i'm sure you can understand why i have no room for lights. Also this setup is pretty stealthy which i like. If my calculations arent correct feel free to correct me please.