Temperature problem

hmm well temps are about 30'c now only got a week to go but i need to suss these temps, Ive had a high idea it might work or it might fail but before i try it can any one gimme some feed back as if it could be plausible?
basicly fill a completely airsealed jar with ice ( or ice an dice coldwater) and leave it in the corner of the room? ( probly need to be changed twice a day) but i dont think it would cause humidity problems as no vapour can escape
is this a stupid idea or could it work?

any one? bump

go for it dude if you have the ice and the will. it wont do any harm. let me know your result. but 30 ok to grow in anyhow

mm that ice idea was a bit of a stoner moment, so i didnt go ahead with it, ive added a second outtake fan with ducting from the light drawing out the heat temps are at 28c now think ive sussed it