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High-Efficiency Fans for Ventilation and Cooling

alternative practice names:

Ventilation fans are used on most dairy farms to improve cow comfort, reduce heat stress, and improve milk yields in hot weather. Dairy farms typically use circulation fans to move air through the barn, and some dairy farms use exhaust fans on one or both sides of an enclosed barn to create cross-ventilation. Regardless of whether a dairy farm uses circulation fans, exhaust fans for cross-ventilation, or both, the fans available to choose from have a wide spectrum of efficiency. 


Fan sizes typically range from 24 to 86 inches in diameter, and fan efficiency is affected by the diameter of the fan as well as motor type and blade design. A less common type of high-efficiency fan is called a “high-volume, low-speed” (HVLS) fan, which are installed at the top of the barn and typically have blade diameter of 6 to 24 feet.


The most common metric of fan efficiency is called the Ventilating Efficiency Ratio (VER) and is equal to the cubic feet per minute of air moved (CFM) per input Watt required to run the fan (abbreviated as “CFM/W”). However, the efficiency of circulation fans is also sometimes measured in pounds of thrust per kW of input power (abbreviated as “lb/kW”). In either case, the higher the number is, the more efficient the fan is.

When used, in what regions in the U.S. is the practice found: 

Northwest, West, Upper Midwest, Southwest, Northeast, Southeast

FARM SIZE 

When used, typically found on farms of the following sizes:

All Sizes

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Practice Benefits 

Increased profitability: The main benefit of installing high efficiency fans is to improve profitability by reducing the amount of electricity used to move the desired amount of air in the barn. Further profitability can be realized through automated control of the fans using variable speed drives to modulate the speed of the fans using temperature and humidity sensors.


Improved milk yield: Milk yield can be improved by optimizing airflow to cool the cows. 

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Implementation Insights

Site-specific or Farm-specific requirements 

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  • Need for efficient cooling: High-efficiency fans present an opportunity for most dairy barns that have less efficient fans installed, or where there are no fans installed and cows can benefit from additional seasonal cooling. 

  • Size and type of operation: The type, size, and style of fans that are appropriate to install depend on the size and layout of the barn. For example, some barns are not able to accommodate high volume low speed circulation fans due to the height or shape of the barn roof. Additionally, the number of fans required to meet a farm’s cooling needs will depend on local weather factors and the volume of air moved by each individual fan.

Required Capital Expenditures (CapEx)

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  • Fans: Converting from a naturally ventilated barn with or without circulation fans, to an enclosed barn with cross-ventilation would be a much more costly and complex project requiring significant from an engineer and possibly an architect.  In some cases, the number of high-efficiency fans needed to meet airflow requirements will reduce the number of fans in the barn (for example, replacing 36” panel fans with 72” fans that more than double the airflow per fan). 

  • Labor: The primary expense for this practice is the fans themselves, and the labor required to install them, as well as disposal of the old fans if applicable.

  • Electrical planning: Additional electrical planning may be needed where fans are not being replaced on a one-to-one basis. High-efficiency fans are available in both single-phase and 3-phase models, although some models are only available in 3-phase. 

Required Operational Expenditures (OpEx)

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  • Maintenance: Ongoing maintenance costs for operating high-efficiency fans will either be comparable to existing fans or can be reduced by installing lower maintenance fans, such as those with electronically commutated motors and fans without belts. Circulation and exhaust fans typically have very long useful lives when properly maintained, usually exceeding 10-15 years.

  • Electricity: Operating expenses associated with electricity can decrease significantly by installing high-efficiency fans.

Implementation Considerations

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  • Efficiency ratings: When selecting high-efficiency fans, it is critical to look at the efficiency rating, typically reported on the manufacturer specification sheet in terms of CFM/W (the higher the number, the less electricity the fan will use). Testing of a fan’s efficiency should ideally be conducted by an independent third party. The most reliable source of agricultural fan efficiency data is the BESS Lab at the University of Illinois

  • Model: Another important consideration is the type of motor and fan construction. The latest technology dairy fans use electronically commutated (EC) motors, sometimes referred to as ECMs. Dairy fans with EC motors offer higher efficiency, longer lifespan, and better controllability with less ongoing maintenance. Regardless of which model of fan is installed, it is recommended to keep the fans clean of debris and dust and keep belts tight if applicable.

  • Software: Dairy farms can greatly benefit from working with an experienced dairy fan vendor or manufacturer that have specialized airflow modeling software to optimize the layout and operation of fans to minimize energy use and maximize cow cooling.

Financial Considerations and Revenue Streams

PROFIT POTENTIAL

Installing high efficiency fans in a dairy barn can significantly reduce electric costs of the dairy farm in warmer months, both from reduced electricity (kilowatt-hour (kWh) usage), and from reduced demand (kilowatt (kW)) charges. 


FEDERAL COST-SHARE AND CONSERVATION FUNDING

Funding is available for this practice through USDA's Natural Resources Conservation Service (NRCS) Environmental Quality Incentives Program (EQIP) On-Farm Energy Initiative.

Notes:

  • An Agricultural Energy Management Plan (AgEMP), or other qualifying energy audit, needs to be completed before applying for EQIP assistance.

  • Check with the local NRCS office on payment rates and practice requirements relevant to your location.


The USDA Rural Development Rural Energy for America Program (REAP) also offers competitive grants and loan guarantees for installing energy efficiency projects.


OTHER CONSERVATION FUNDING

Fan rebates are sometimes available through the farm’s electric utility company.  

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Environmental Impacts

REDUCES FARM GREENHOUSE GAS FOOTPRINT

Improving energy use efficiency reduces a farm's greenhouse gas (GHG) footprint. Since energy production typically involves processes that emit greenhouse gases like carbon dioxide and methane, cutting energy use directly lowers the GHG footprint of the farm.

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Alignment with FARM Program

FARM Environmental Stewardship (ES) V2-V3 Alignment

FARM ES captures a farm's energy usage and calculates the associated GHG emissions based on regional energy production and transmission averages. Any practice that reduces farm energy consumption will directly lower the farm's GHG footprint. The reduction in GHG emissions is particularly pronounced in regions where a larger proportion of energy is derived from coal, natural gas, or other fossil fuel sources, as these energy types have higher carbon footprints compared to renewable energy sources.

Contents

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We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

Contents

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Practice Overview

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Ventilation fans are used on most dairy farms to improve cow comfort, reduce heat stress, and improve milk yields in hot weather. Dairy farms typically use circulation fans to move air through the barn, and some dairy farms use exhaust fans on one or both sides of an enclosed barn to create cross-ventilation. Regardless of whether a dairy farm uses circulation fans, exhaust fans for cross-ventilation, or both, the fans available to choose from have a wide spectrum of efficiency. 


Fan sizes typically range from 24 to 86 inches in diameter, and fan efficiency is affected by the diameter of the fan as well as motor type and blade design. A less common type of high-efficiency fan is called a “high-volume, low-speed” (HVLS) fan, which are installed at the top of the barn and typically have blade diameter of 6 to 24 feet.


The most common metric of fan efficiency is called the Ventilating Efficiency Ratio (VER) and is equal to the cubic feet per minute of air moved (CFM) per input Watt required to run the fan (abbreviated as “CFM/W”). However, the efficiency of circulation fans is also sometimes measured in pounds of thrust per kW of input power (abbreviated as “lb/kW”). In either case, the higher the number is, the more efficient the fan is.

Practices and technologies

High-Efficiency Fans for Ventilation and Cooling

alternative practice name: