I have a pair of gable vents in my new coop and find them to be a nice addition to most any building, new or old. I have paired them with hardware cloth screened soffits and a ceiling/roof mounted twelve inch turbine vent. Between these three methods, one or more seems to always be working. Through this winter my coop has been bone dry, and no ammonia smell to foul the fowl's air. As noted prior, shuttering them and or another choice of closing them down as needed would be a wonderful management scheme.
Best to you and your birds,
RJ
Best to you and your birds,
RJ