Fresh air will be introduced to the poultry housing system through fresh air inlets. Air inlets can be installed in the wall inside the hen house or in the ceiling or they can be molded directly in the precast concrete element. With a little air intake opening, fresh air will be provided without draft, whereas with inlet open wide, the cooling will be more effective. Most often, the outgoing air is directed through exhaust air chimneys on the roof. Ventilation can be directed and cooling of the air boosted with giant tunnel fans attached to the end wall. These fans, which are particularly designed for special circumstances, are quiet-running and effective.