For confined livestock, ventilation (pig barn ventilation, swine barn ventilation, or other livestock ventilation systems) is of utmost importance. Proper ventilation in pig barns improves the air quality and reduces the chance for illness, decreased pig productivity, and loss of profits.

The two basic forms of ventilation are natural ventilation for pig barns and mechanical ventilation in hog barns. Negative pressure ventilation, the most common form of pig barn ventilation, utilizes a combination of inlets and fans to allow fresh air into the pig barn while exhausting stale air. This approach is crucial for pig barn airflow management, controlling humidity, and controlling ammonia levels in pig barns—key factors in reducing odors in swine production.

The main function of hog barn insulation is to address how to prevent condensation in a pig barn. In production facilities, insulation only needs to maintain a surface temperature above dew-point temperature. Walls do not require an R-value insulation for livestock buildings higher than the mid-teens; ceilings typically require an R-value in the mid-twenties.

A significant amount of cold-weather heating is lost through normal ventilation air-exchange (important for moisture control in swine facilities), so insulation beyond these ranges offers limited benefit. .

To prevent insulation from absorbing moisture, a vapor barrier must be used. This prevents moisture inside the barn from creating condensation inside the walls. Insulation must likewise be protected from rodents. Crushed stone or ample baited traps at the base of exterior walls will help prevent rodents from getting in the walls and destroying insulation.

Rigid-board insulation two to three feet below ground level helps with maintaining humidity levels in hog barns by reducing condensation. An R-value between six and eight is usually sufficient. This setup also helps keep floors more comfortable for pigs in cold months.

A natural ventilation for pig barns system typically uses ridge or roof vents and side inlets. Warm air in the building rises and exits, drawing in cooler outside air. However, this airflow depends largely on outside temperatures and wind, making it difficult to regulate precisely. When indoor and outdoor temperatures are similar—or outdoor temperatures are higher than indoors—there’s very little ventilation, potentially impacting moisture control in swine facilities.

In a natural ventilation system, the amount of ventilation can’t be controlled because it depends on the indoor and outdoor air temperatures and the wind, if any. When outdoor and indoor temperatures are the same, or when outdoor temperatures are higher than indoor temperatures, there is very little ventilation.

Consequently, natural ventilation airflow is difficult to control.

In mechanical ventilation in hog barns, fans create the pressure difference between the inside and outside of the barn—crucial for pig barn airflow management. Systems can be positive, neutral, or negative pressure.

In a positive pressure system, fans draw outside air into the facility, forcing the inside air out of the facility through exhaust pipes or ducts. Positive pressure systems are not common in pig facilities because of the chance for warm, humid outside air to enter the structure, leading to possible condensation. 

A neutral pressure system utilizes fans both for drawing air in and exhausting air out of the building. The neutral pressure system does not make use of structural elements like inlets or windows. Instead, vertical inlet ducts distribute air evenly throughout the building with directional air vents pointed at the walls and corners of the building.

The larger air vents are pointed at the corners, typically the greatest distance from the vertical duct, and the smaller vents are directed at the walls. This will help prevent drafts. Inlet fans should be evenly distributed in the center of the room. Exhaust fans placement is less important as they do not affect airflow patterns.

Neutral pressure systems are expensive to operate and maintain, as they require twice as many fans as other mechanical ventilation systems.

The negative pressure air system is probably the most common method for ventilating pig barns—they’re easily controlled and cost efficient when compared with the other forms of mechanical ventilation. A standard system makes use of sidewall inlets and a central exhaust fan. Cold air enters the facility and mixes with the warm interior air before reaching the animals. During cold months, inlets should direct the incoming cold air up, toward the ceiling, and down, toward the floor, during warm months.

For wider buildings, inlets can be installed in the ceiling. In this case, air enters through the roof.

Some buildings use floor ventilation in combination with standard negative pressure wall inlets. The advantage of floor venting is that a substantial percentage—up to 50 percent—of stale air is removed below floor-level. This is advantageous as most ammonia is removed before rising to pen-level in slatted facilities, reducing odors, providing an improved working environment and a healthier living space for swine, especially when combined with pit fans.

Any mechanical system is only as good as the fans. Ventilation fan maintenance using a fan maintenance checklist for pig barns—at least at the start of fan season—ensures peak performance. Checking fan blades, bearings, belts, and sheaves for wear is critical. Even minor dust buildup can reduce efficiency. A company like DURAFAN, that offers a wide variety of high-quality fans and replacement parts, is a great choice for consistent, high-performance ventilation.

Does your facility use a negative pressure ventilation system? Or something else? Tell us in the comments section!