BTW, in looking up air exchange numbers for commercial operations I came across the following, which is an interesting read. Remember it is really aimed at giant commercial poultry barns with forced-air systems. However, a lot of the general concepts apply well to backyard coops too:
http://www.aviagen.com/docs/AviaTechWinterVent.pdf
Notable points: seal leaks, so air is coming in only through intended openings, to minimize dampness from condensation in the coop. Insulate. Increase ventilation as needed according to birds' growth etc. Have cool air coming in high up, and ideally mixing well with coop air before hitting the birds. If dampness or smell become a problem, increase ventilation.
Pat
http://www.aviagen.com/docs/AviaTechWinterVent.pdf
Notable points: seal leaks, so air is coming in only through intended openings, to minimize dampness from condensation in the coop. Insulate. Increase ventilation as needed according to birds' growth etc. Have cool air coming in high up, and ideally mixing well with coop air before hitting the birds. If dampness or smell become a problem, increase ventilation.
Pat