By Casey L. Bradley, Ph.D.

The three primary nutrients pigs need to thrive are water, feed and air. Proper ventilation is important because it reduces gaseous buildup, removes excessive moisture or humidity, and maintains ideal thermal neutral zones.

Traditionally, swine facilities were equipped with a three-stage fan system and pit fans for ventilation. Today, if you consider the advancements in tunnel ventilation and positive or negative air pressure systems for filtration, the ventilation needs have changed dramatically. Additionally, using modern-day controllers, ventilation possibilities have become limitless.

Understanding energy costs of ventilation

Dr. Ben Smith, a researcher with Iowa State University focusing on precision agriculture, provides some great insights to better understand ventilation and associated energy costs. For starters, two aspects must be considered when discussing the relationship between energy usage and air movement. The first main point is that fan speed and air speed are proportional, and the second is exponential concerning energy usage. For instance, a 10% increase in fan speed results in approximately a 10% increase in air speed or velocity. However, increasing fan speed results in an exponential increase in energy usage and dollars in your electric bill.

The University of Georgia Cooperative Extension conducted a research trial evaluating the number of fans running and total fan power. Czarick and Fairchild (2017) found that running more fans at a slower speed could save up to 40% in energy usage. Another way to reduce power usage is with a variable speed fan, which can run with variable voltage continuously to maintain set environmental conditions. However, the transition with these fans was slowly adopted due to the limitations of controllers and operator management. During the same study, Czarick and Fairchild (2017) demonstrated that utilizing a 55-inch variable fan versus a standard 48-inch fan reduced fan power usage by up to 65%.

Advancements in ventilation

The traditional ventilation program for swine barns included a three-stage fan program. Different fans would turn on and run at full velocity based on set temperatures and time intervals. However, to advance ventilation, companies designed new controllers to adjust the voltage to allow fans to spin at a lower RPM. This could also be done by adjusting the pulley or belt size.

Additionally, positive or negative pressurized filtered barns have also driven the need for variable speed fans to maintain a specific static pressure to function correctly. However, the lower voltage was not the intended purpose of these new controller capabilities, as fan motors rely on air movement to regulate motor temperature.

The main concern is that direct voltage alteration is not proportional to fan speed and does not account for external factors such as headwinds or static pressure. The fans thus build up internal temperatures that lead to higher maintenance requirements, like motor or belt failure. One of the solutions to limit these critical control points with variable speed fans was the invention of permanent magnet synchronous motor fan technology, which is now available to pig producers through products like the Hero Fan by PigTek.

PMSM technology was designed to tackle the main challenges with variable-speed fans. First, the direct-drive motor design does not include belts, tensioners, or bearings, since these caused many failures and maintenance problems with the original variable speed fan motors. The PMSM motor design meets IE5 standards, the highest energy efficiency level for motors, and runs 30% cooler than the IE3 rating for commonly used motors. Secondly, the complete fan assembly is made of stainless steel with cast aluminum for the blades, providing corrosion resistance to further reduce maintenance needs.

To complete the entire package, PMSM drives can efficiently monitor feedback, current, voltage, drive temperature and other parameters. The system communicates with the ventilation controller to adjust fan speed based on barn conditions.

Complete retrofitting with PMSM technology is not always necessary, as these fans can be utilized in combination with traditional single-speed fans. As a variable-speed fan begins to reach inefficient speeds, the controller can turn on a traditional single-speed fan and lower the variable-speed fan to maintain optimal conditions while saving on energy costs.

As a result, variable-speed fans with PMSM technology take the guesswork out of ventilation. They optimize energy usage, which results in fewer input costs and potentially better profits by ensuring the proper level of ventilation is achieved with the least amount of money. Furthermore, if reduced maintenance and energy costs are not enough to seal the deal, potential tax rebates make PMSM solutions a sweet deal to improve animal comfort and profitability for any swine production system.