i ran a 150w hps in a small closet w/o ventilation and couldn't keep my temps below 90. even with fans running constantly and opening the door every few hours.

it ended up being too much of a pain. now i have a t5/cfl setup and it's much easier. i keep the doors closed up all day with a couple of fans running and have no heat problems. i had to give up some lumens with the swap, but it was worth it because plants grow much better when they aren't burning or heat stressed.

so if you can't ventilate i recommend looking into T5s or CFLs.