Closet growroom + fans

Hey. New to the message board. Hello to all. Quick Question;
I'm setting up a simple closet hydro set-up for four plants. Gonna use 250w light. How neccessary is a cooling/extractor fan? My plan was to open the doors of the closet at intervals during the day and allow a standard household oscillating fan blow in on the plants. Totalling about 3 hours a day (I work from home, hence I'll be near the plants all the time).

Will this work as I want to avoid the expense, noise and construction of a fan within the cupboard. I need to keep it looking like a normal cupboard as best I can.

Any feedback appreciated.

Should post this in the grow forums. You're more likely to get a solid answer there. :)

Cheers sawleaf