Air pressure

[PatriceUK]

Hey guys, I have a small problem that I am struggling to overcome. I have built a solid grow area out of timber within my spare bedroom. I ventilate the air into the attic through a pipe going through the ceiling. I have boarded over the window but I keep it slightly open and run my intake through that board to draw in fresh air from outside.
I would like to be able to close the door to this bedroom but the negative pressure creates noise via air rushing in around the edges of the door.
I can temporarily handle the problem if I open the window further, turn off the intake and reduce the outake dramatically. But this is a lot of hassle as it means unscrewing one of the boards which cover the window.
I'd like to be able to have the door to that room closed all day as my girlfriend is moving in soon and she won't be unscrewing panels everytime someone calls over.
I can't open the window any wider without it being a security risk and I get mould/rot when I run my fans on a low speed.
I have been looking at brick vents which look quite straight forward but I'm not sure if they would be sufficient. I have also considered running a pipe down to the room below with a vent on the ceiling which would act as a passive intake and would be quite easy to do.
Has anybody run into a similar problem? I'm not sure on the best way to handle this problem, I'd appreciate any advice.

 

[oldskol4evr]

nail a sleeping bag to the trim of the door,i did this to stop light leaks and it worked very well also kept my cool air from escaping the closet,i had a attic trap door in there,i removed the board there and made a new one from the 3/4 in styrfoam boards from home depot,i made 3 6in holes in it,i took 1 6 in hose and ran it threw the attic and spliced into a ac register going into the room with a y pipe,then i took another 6in vent hose running off my cool tube and exhaust it directly into the attic,the third 6 in vent hose ran across the attic and to a sofit vent on eve of house and sucked in the outside air,after tiddy every thing up and drop the little make shift door right back into the home postion of it frame,when i moved from the house wasnt any problem to put a coupling back into the ac vent back to the register,took me about 2 days to get it all set up and about 20 min to tear it all back apart