The vents are just the painted 4" PVC vents bought from Home Depot. They are for passive ventilation only, not for active air exchange, thus a square window on every wall. As for the windows next to the roosting bar...my chickens like to look outside. In the summer, those windows are wide opened.
As you can see from this picture, my daily cleaning is to remove just the two poop boards to scrape off the poop, hose them with water if needed, no sieving necessary. The poop boards made of 1/16" rigid plastic panel cut to size, smooth surface with a 1" lip on 3 sides only, very easy to clean.
Nice! I like this design. Very tidy.