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Natural Ventilation Systems

Ventilation is critical to the health and production of animals in modern farming operations. Livestock producers are continuously looking for efficient and cost-effective ways to keep their barns in optimal environmental condition. In this article we are going to look at natural ventilation, which is sometimes called “passive ventilation”.

A natural ventilation system creates airflow using natural factors such as wind and temperature differentials, with the goal of producing a healthy and comfortable animal habitat. We will look at the benefits, uses, and considerations of natural ventilation barns for livestock.

Introduction to natural ventilation

Natural ventilation originated from the time when farmers would leave barn doors open to reduce moisture and heat accumulation in animal shelters. Modern naturally ventilated barns are much more advanced, but still follow the main principles of this age-old practice. Today, a sophisticated natural ventilation system plays a crucial role in enhancing the well-being of animals by drawing fresh air into the barn and expelling it through a series of strategically placed components.

How natural ventilation works

Natural ventilation uses variations in wind pressure and temperature. During winter, the wind travels over the building, generating suction the draws out warm, moist air. This process helps bring fresh air into the building through strategically positioned openings or curtains. In summer, optimal ventilation is achieved by opening large portions (typically one-third to one-half) of the sidewalls. This promotes a cross-flow of air that effectively cools the barn environment and purges it of dust and hazardous gases like ammonia. Basically, a natural ventilation system works like a wind tunnel, moving air quickly. This not only cools the animals but also improves the air quality in the barn.

Advantages of natural ventilation

Natural ventilation has several advantages over mechanical ventilation, including:

  • Often less expensive to design and build
  • Less expensive to operate
  • Significantly less energy use, more environmentally friendly
  • Less maintenance
  • Provide ventilation during power outages*
  • Provide natural light when curtains/panels are open
  • Reduced animal stress and better working conditions due almost silent operation and less humidity, odour, and harmful gases

* Power outages in mechanically ventilated barns provide a significant risk of animal suffocation, the costs of which can be in the tens of thousands of dollars depending on the size of the facility.


Industry Applications Suitability for use
Dairy All Very common
Poultry Especially turkeys Sometimes
Swine Farrowing and nursing Rare
Swine Finishing Sometimes

Farmers that raise larger animals that require confinement typically use natural ventilation systems with sidewall and ridge apertures increasing airflow through the facility.


Proper location of the building concerning prevailing winds and surrounding trees, structures and land formations is essential to the success of a natural ventilation system.

During periods of changing weather conditions, sidewall doors and inlets should be adjusted several times a day to avoid a sudden temperature change in the building.

  • Inlets open
  • During severe winter weather, inlets may be partially closed, NOT COMPLETELY CLOSED
  • Sidewall and end wall openings closed and fastened
Mild winter/spring/fall
  • Inlets fully open
  • Upper sidewall and end wall openings adjusted to maintain a comfortable animal environment
  • Inlets open
  • Sidewalls completely open to provide air movement in the animal zone


In conclusion, ventilation stands as a crucial element for maintaining the health and productivity of animals in modern farming, and natural ventilation emerges as a cost-effective and efficient solution.

These systems have several advantages over mechanical alternatives, including lower costs, reduced energy consumption, and improved animal well-being. Natural ventilation systems offer benefits such as reduced stress, minimal maintenance, and the ability to provide ventilation during power outages.

Overall, natural ventilation systems, with their roots in age-old practices, continue to play a vital role in creating healthy and comfortable environments for livestock in modern agriculture.

Phason’s Natural Series, NVC-2 and SPC-2, are excellent choices for controlling natural ventilation systems. These controls can control variable and fixed-stage fans, inlets and vents, curtain machines, and much more. The Touch Series and AutoFlex Connect can also control natural ventilation systems.