Operational benefits and design considerations for HVLS ...

09 Sep.,2024

 

Operational benefits and design considerations for HVLS ...

Over the last 10 to 15 years, we have seen the introduction of large-diameter ceiling fans into the design of freestall dairy facilities. High-volume, low-speed (HVLS) fans were originally designed and used in large commercial warehouses and production plants, and the first livestock application was for riding arenas in the large equine markets of the U.S. From there, HVLS fans were experimented with in dairy barns and proved to be quite effective at improving cow comfort.

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Rick McBay

Natural Ventilation Specialist / Canarm AgSystems

Rick McBay has provided producers with equipment and ventilation solutions for the past 40 years.

Rick McBay

The purpose of HVLS fans is twofold depending on if it is operating in forward or reverse. When the fan is set to run in the forward direction, it creates a column of air the same size as the fan diameter directly downward, which then radiates a wave of air approximately 4 feet high out from the fan in a 360-degree pattern. Due to the large size of the fan blades &#; up to 24 feet in diameter &#; the air moves at high speeds, creating a velocity cooling effect for the animals as it passes over them.

Operational benefits

For hot-weather operation, HVLS fans are operated on a variable-speed basis with an automatic temperature controller. This will start the fans at a set interior temperature and speed them up or slow them down based on changes in the interior temperature. This is especially helpful during the spring and fall, when outside temperatures can vary dramatically over a 24-hour period.

During cold-weather operation, when operating in reverse, HVLS fans can be used to push air upward, which will destratify any heat that is layered along the ceiling and recirculate it gently throughout the building. Typically, this is accomplished by utilizing a variable-speed control and having the fan running at a constant speed of approximately 20%. An added benefit when operating in reverse in a natural ventilation system is: The air moves over the inside of the sidewall curtain fabric and reduces the potential for condensation buildup in cold weather.

Since HVLS fans cover large areas and use a three-phase motor, the operating costs will be lower in comparison to a larger number of small high-speed fans. In fact, in some areas of North America, the local power authorities are offering substantial rebates to encourage the purchase of HVLS fans.

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In some instances, operators have found that since birds can see the slow-moving blades, they are less likely to enter the barn when these fans are operating. However, this may not always be the case. If there are perch points created where the fans are mounted, birds may still tend to roost and nest. 

HVLS fans can play an important role in an inclusive fly control program that should be in place in your operation. The high-speed air flow they create within the building can also help reduce the number of flies during hot weather. 

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Design considerations

If you are operating a freestall dairy with large sidewall curtain openings, the fans should be mounted at a height that is above the curtain opening. Due to the length of the blade, there can be flexing in windy conditions that can cause the blade to break. HVLS fans are typically available in sizes from 8 feet to 24 feet in diameter, and the smaller units will prove to be more resistant to wind damage. It is also advisable to use a controller that has the capacity for wind sensor input so the fans can be automatically shut down in windy conditions. 

In hot weather, cows will tend to stand directly under the fan where the air is coolest, so when placing the fans within the building, you should avoid having them over areas where cattle can congregate and create blockages such as scrape alleys. 

When creating the fan layout, avoid having a fan mounted directly under a light fixture, as the rotation of the fan blade can cause a strobe light effect which will create an uncomfortable visual element for your cattle.

As with any ventilation system within your dairy, you should consult with a ventilation specialist who can advise you on the size and layout of HVLS fans that will work the best for you and your cows.

Large HVLS Barn Fans Built for Livestock and Farms

The benefits of HVLS industrial outdoor fans may be obvious for commercial applications, but how, precisely, are they relevant as livestock fans? You may be surprised to learn that barn ceiling fans offer many benefits to agricultural settings.

Improved Air Circulation

HVLS barn ceiling fans generate a gentle breeze that spans a wide area. This ensures adequate air circulation throughout the entire barn, eliminating stagnant air pockets and promoting consistent temperature distribution. The improved air circulation mitigates temperature variations, reducing hot and cold spots within the barn, creating a more comfortable environment for livestock and enabling them to effectively regulate their body temperature.

Heat Stress Prevention in Livestock

Heat stress is a significant concern for livestock, especially in hot and humid climates. Industrial outdoor fans help prevent heat stress. The gentle breeze produced by HVLS fans facilitates the evaporation of moisture from the animals' skin, allowing them to dissipate excess heat and maintain a comfortable body temperature. By reducing the risk of heat stress-related illnesses, such as heat exhaustion or heat stroke, HVLS barn fans contribute to the livestock's overall well-being and health.

Reduction of Humidity and Condensation

Excessive humidity levels and condensation lead to unfavorable conditions in livestock barns, promoting the growth of mold, mildew, and bacteria. This poses a risk to animals and farm workers. HVLS livestock fans assist in controlling moisture levels by promoting air movement and aiding in the evaporation of excess moisture. This helps to reduce humidity, preventing the accumulation of moisture and the subsequent growth of harmful microorganisms. By maintaining appropriate humidity levels, HVLS fans create a healthier and more hygienic environment.

Enhanced Air Quality in Barns

Livestock barns are prone to poor air quality due to the accumulation of dust, gases, and odors. HVLS agriculture fans effectively combat this issue by creating a constant flow of air that helps to remove airborne contaminants. The gentle breeze generated by HVLS fans facilitates the dispersion and dilution of dust particles, reducing their concentration in the air and minimizing the risk of respiratory problems for both animals and humans. Additionally, HVLS fans aid in dissipating unpleasant odors and gases, providing a more pleasant and healthier working environment for farm workers.

Increased Productivity and Performance

The optimal ventilation and comfort provided by HVLS barn fans positively impact livestock productivity and performance. By maintaining a consistent and comfortable environment, HVLS fans help to reduce stress among animals. This, in turn, promotes better feed intake, improved growth rates and enhanced overall productivity. The reduction in heat stress and improved air quality created by HVLS fans contribute to the overall well-being of livestock, leading to better health, lower mortality rates and increased profitability for farmers.

Energy Efficiency and Cost Savings

HVLS barn fans are designed with energy efficiency in mind. They consume significantly less energy than traditional high-speed barn fans or air conditioning systems. The low rotational speed of HVLS fans results in lower power consumption while still providing effective air movement and circulation. Additionally, agricultural fans are controlled remotely, so you can change the settings based on current needs, thereby delivering the most efficient airflow and maximizing energy output.

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