I put my enclosure in front of an east facing window, where I leave the window open all day. It gets a lot of sun in the morning until noon and a lot of ambient sunlight (more than enough to light the rest of the room) the rest of the day. The light does filter through a screen in a window and the enclosure, though. I also have a reptisun 10.0 that needs replaced by august that I leave on, I figure it has some UVB left, even if it wouldn't be ideal on its own.