Ammonia, carbon dioxide and moisture are all produced in cattle houses. As gases, these products can be harmful to animals, people and the environment. Furthermore, a damp animal house is also a breeding ground for all kinds of germs. Mastitis, heat stress, claw damages and fly nuisance are all problems that can occur as a result of a non-optimally controlled climate in the cattle house. The main purpose of ventilating is to achieve and maintain a good quality of air in the house.