If you look at my Jedi thread you can see the space I grow, it is 23.5" x 23.5" around 5.5' tall. To be fair the fan/variac and muffler all sit outside of the grow box, with a small grow room and 400W light I needed a lot of air circulation for temp control. Even when running my 90W UFO and a couple 43W CFLs I need the airflow in there. Is it overkill, maybe

But it works and the sound is low enough it can be masked with a window fan or PC.