How to prevent light out of the window

[Invisible Rasta]

Hello guys, I am building a room and I have a chimney as exhaust and a window with shutters as intake of fresh air. The problem im having is figuring out how to make it so the light wont go trought the window. Any suggestion?

 

[superx]

I use reflective sheeting, its 3 layered white/black/white on the inside then i position a white net curtain in front of it, complete black out and if you looked at it from the opposite side all you see is the white net curtains works a treat, what do you mean by shutters?

 

[CoCoSativas]

Poly over the window with white reflective poly, white in toward the grow black out so it looks like a dark room.

Poly goes right over the window covering and is not obvious it just looks like the rooms totally dark.

This stuff dosent let light pass its 3 mil... its also more flexible than mylar by a long shot. I quit mylar this is all i use.

You can use staples or drywall screw to hang it then tape it sealed. If you need it to draw air in leave the bottom only partially stapled down...