Mine has the back open and the full front\half top lid, but I still occasionaly have some heat problems in the summer. A lot of it will depend on what temp you keep your house and also what kind of lights you are running. I have t5's that I am overdriving so they get hotter than most, but I also have some computer fans blowing over them. The best thing to do in my opinion is build it so that if changes need to be made (things added or removed) they are easy to do. Just mt 2 cents. Good luck and we would love to see pics when you are finished.