Chickens don't NEED windows, although it's nice to have. Windows add light, which helps to extend the day inside the coop, helping with egg production. Windows help heat the coop in the winter time (if they are glass, plexiglass). Screened/wired windows help airflow during the hot months. But if you have proper ventilation, windows aren't required. Many people say that chickens prefer to lay their eggs in dimmer, more secluded areas, so most folks try to place the nest boxes in out of the way spots inside the coop (although my nest boxes sit directly across from a window and my girls have used them well from the get-go).
Your ventilation definitely sounds minimal...see if you can find a way to add more. Make sure that it is above the birds' heads when roosting so as not to result in drafts on them...