I have spent the weekend expanding my coop to make room for more chickens, my question is how much ventilation is needed. I left quite a lot of vents at the top of the coop, basically gaps between the sides and roof whick i have covered in wire mesh for safety against predators. I am also adding 2 windows for extra ventilation and light, is this enough? i am worried about how drafty it might be. The coop is roughly 12ft x 5ft, is what iv'e done ok or do i need more or less?. Any help or suggestions will be appreciated as it's coming to winter now here in uk and i want my birds to be comfertable and safe.