http://www.abe.psu.edu/extension/factsheets/g/G92.pdf Air, like some people, takes the path of least resistance. Broken windows, open hay chutes, manure gutter openings, open doors, and all those cracks in the wall provide equal-opportunity inlets for the air. These unplanned inlets generally produce dead air spots, drafts, uneven temperature and humidity levels throughout the barn, and undesirable air quality. All these poor air flow characteristics can be improved through the installation of planned inlets. At the same time, those old unplanned inlets need to be blocked (broken windows fixed, cracks sealed) or managed better (doors closed). Designed and installed properly, inlets provide fresh air evenly throughout the room without causing drafts.