To remove carbonic gas, water vapor, ammonia and dust from poultry houses and to provide livestock with fresh air (oxygen), it is necessary to maintain constantly a certain level of ventilation in the room. This type of ventilation is called basic. The basic ventilation within 0.7–2.5 m³/h is sufficient to maintain concentration of carbonic gas and humidity within the maximum permissible values. The majority of modern ventilation systems are based on the principle of negative pressure. They should provide the required level of oxygen in winter and transition period, low power consumption, uniform air distribution, mixing with warm air before entering the operation area. The widespread scheme with air supply through side valves and exhaust through shafts or end fans complies with these conditions.

Another way to implement this scheme is to supply air through ventilation shafts. Uniformity of supply elements determines the uniformity of the room microclimate by 80%. Installing fans in supply shafts allows to implement an equal pressure system, the distinctive feature of which is the least dependence on external weather conditions, influence of wind and sudden changes of temperature. In the first case the following conditions should be met: the exclusion of uncontrolled air leaks, ensuring tightness of the air distributors in closed position, and the ability to adjust the volume and speed of the incoming air as well as its direction during operation. In case of the equal pressure system, the requirements for the room sealing are not critical. The system itself ensures uniform distribution of clean air and removal of exhaust air. This is an undisputed advantage of these systems.