In hot climates there is no such thing as too much air until you're getting storm winds right on the birds at roost level with no shelter available. :)
My new Open Air coop that we're building will have vent space all around under the roof overhangs in the 3-sided shelter at the windward end...
#1 factor is the almost complete lack of ventilation. In a hot climate your chickens will be roasted alive.
Rule of thumb -- If it looks like a dollhouse it's only suitable for toy chickens. :D
Texas is an ideal place for an open air coop -- a wire enclosure with a roof and shelter from the...