Ventilation System Selection Logic for Small and Medium Pig Farms

Introduction: When Bigger Fans Create Bigger Problems

During the construction or renovation of small and medium pig farms, ventilation systems are considered essential. However, a common misconception still exists: many farm owners believe that the larger the fan and the higher the airflow, the better the ventilation performance. In reality, this approach often leads to higher investment without proportional returns. Excessive airflow can increase energy consumption, create uneven temperature distribution, and even cause stress in pigs.

For pig farms with an annual capacity of 300–3,000 pigs, the goal of a ventilation system is not to maximize airflow, but to achieve stable air exchange, effective cooling, and controllable operating costs. Understanding ventilation selection logic is far more important than simply choosing larger equipment.

What Are the Real Ventilation Goals of Small and Medium Pig Farms?

Before discussing equipment selection, it is necessary to clarify the actual ventilation needs of small and medium pig farms. Compared with large-scale industrial farms, smaller operations have simpler building structures, limited management manpower, and tighter budgets.

In practice, ventilation systems in these farms serve three main purposes:

First, to ensure sufficient air exchange, removing ammonia, hydrogen sulfide, and excess moisture to maintain acceptable indoor air quality.
Second, to reduce heat stress during hot seasons by working together with cooling measures, protecting feed intake and growth performance.
Third, to operate reliably with simple maintenance, avoiding complex systems that increase daily management burden.

If fan selection deviates from these goals, higher equipment specifications will not translate into better farm performance.

Airflow Demand: “Enough” Is Better Than “More”

The core parameter in ventilation design is total air exchange capacity, not the rated airflow of a single fan. In many small and medium pig farms, problems arise because individual fans are oversized.

When airflow significantly exceeds actual demand, several issues commonly appear:

• Excessive air velocity inside the pig house, causing cold stress during non-summer periods

• Short-circuit airflow, where fresh air exits before fully circulating

• Higher energy consumption with limited environmental improvement

A more practical approach is to calculate the required total airflow based on barn volume, stocking density, and seasonal demand, then achieve it through multiple medium-capacity fans rather than one oversized unit. This improves airflow control and reduces the risk of single-point failure.

Why Negative Pressure Ventilation Fits Small Pig Farms Best

At present, negative pressure ventilation systems remain the most widely used and reliable solution for small and medium pig farms. These systems work by exhausting air from the barn, creating negative pressure that draws fresh air in through designated inlets.

Their key advantages are simple structure, controlled cost, and strong adaptability. Compared with positive pressure or highly automated ventilation systems, negative pressure systems place fewer demands on building precision and control systems, making them better suited for farms with limited technical staff.

When selecting fans, proper layout and quantity are more important than maximum single-fan airflow. Air must follow a designed path through the barn, not escape through dead zones or shortcuts.

Fan Size and Installation Openings: Planning for Future Flexibility

Many pig farms choose to standardize wall openings, such as 1.4 m × 1.4 m, to allow for larger fans in the future. While this approach is reasonable, problems arise when farms install oversized fans from the beginning without considering current needs.

A more balanced strategy is:

• Configure fan capacity according to current herd size and management level

• Reserve structural space for future expansion without overinvesting early

This staged configuration keeps initial costs under control while preserving long-term flexibility.

Large Fans vs. Multiple Medium Fans: A Practical Comparison

From a long-term operational perspective, multiple medium-capacity fans usually deliver better stability and return on investment for small and medium pig farms.

Ventilation Must Work Together with Cooling Measures

In hot seasons, fans do not work in isolation. Ventilation systems must operate together with cooling measures such as cooling pads, misting systems, or shading.

Relying solely on higher fan power often leads to the situation where “air moves fast, but temperature remains high.” This is because cooling is not achieved by airflow alone, but by heat removal through air exchange and evaporation. The role of the ventilation system is to provide consistent airflow conditions that enable these cooling methods to function effectively.

Conclusion: Ventilation Selection Is a Long-Term Management Decision

For small and medium pig farms, ventilation systems are not one-time purchases but long-term infrastructure investments. Instead of pursuing maximum specifications, farm owners should focus on matching airflow capacity to actual needs, ensuring stable operation and manageable costs.

By rationally assessing airflow demand, properly configuring fan size and quantity, and reserving space for future upgrades, small pig farms can build ventilation systems that truly deliver sustainable performance and long-term value.