How much space do I need outside of the case to make cooling effective

[FatalBurrito]

I have just finished my long time project of building a pc into a desk. Now all that needs to be done is position it. The best spot for it in my house is between these two walls. The only problem is on one side the walls are only a half inch from the fans. Can I still put it there? and would it be better to have the intake or exhaust fans there? Thanks

 

[scout_03]

post a picture where you want to put the pc and the place it have in the deck .