Livestock production is significantly influenced by animal health and comfort. Ventilation of animal housing to remove moisture and odors and replacing them with fresh air is necessary for livestock productivity. Ventilation also provides air movement that promotes cooling and improves air quality for confined animals. While good ventilation contributes to profitability, if not properly designed, the energy used by a cooling and ventilation system can significantly reduce those profits.
Passive, or natural, ventilation is the supply and removal of air through openings in a building. It is driven by natural wind flow around the building and temperature differences between the inside and outside of the building. Passive ventilation may be used alone or in combination with some type of mechanical ventilation.
In many cases natural ventilation alone is not adequate, since inside temperatures and air exchange rates fluctuate with outside changes in temperatures and wind conditions. Its use in confinement livestock production is most common in large animal housing, with air passage through sidewall and ridge openings.
Mechanical ventilation is created by fans, thermostats, and air inlets. It is used where the air temperature and movement must be controlled, such as housing for animals that are sensitive to cold, sudden changes in temperature, and drafty conditions. Mechanical ventilation is common in swine farrowing and nursery buildings, lambing sheds, warm dairy cattle barns and calf housing, and milk houses. The most common approach is to use fans to blow air out of the building, with fresh air drawn in through inlets on the opposite side. However, fans can also be placed within a barn to circulate the air and improve uniformity of conditions.
The main advantage of mechanical ventilation is that it provides improved control over temperature and airflow within the facility – even on days when the wind is not blowing.
The primary disadvantages of mechanical ventilation are initial expense and operating cost as well as loss of animal heat in the winter, which may require a supplemental heating system to keep the animals sufficiently warm.
There are two principal types of fans used for mechanical ventilation of animal housing: box type fans and large, low-speed paddle-type fans. Box fans are used in conventional tiestall barns or loose housing such as freestall barns. Large paddle-type fans, also called high-volume, low-speed fans (HVLS) are most suitable for loose housing applications.
- Dairy Ventilation fact sheet by Scott Sanford, University of Wisconsin.
- Basic Ventilation Considerations for Livestock or Poultry Housing fact sheet by James A. Moore, Extension agricultural engineer, Oregon State University.
- Environmental Control for Confinement Livestock Housing comprehensive overview of mechanical ventilation systems for animal housing, by Don D. Jones and William H. Friday, Extension Agricultural Engineers and Sherwood S. DeForest, P.E., Agricultural Engineer, Purdue University.
- Inlets for Mechanical Ventilation Systems in Animal Housing. This fact sheet describes inlet types, design, size, and includes an inlet checklist. Eileen Fabian Wheeler, Assistant Professor, Agricultural Engineering, Penn State University.
- Mechanical Ventilation Design Worksheet for Swine Housing fact sheet by Jay D. Harmon, extension agricultural engineer, Iowa State University.
- Natural Ventilation for Dairy Tie Stall Barns fact sheet by Robert E. Graves, Professor of Agricultural Engineering, Penn State University.
- Natural Ventilation for Freestall Barns fact sheet by Robert E. Graves, Professor of Agricultural Engineering, Penn state University, and Michael Brugger, Associate Professor of Agricultural Engineering, Ohio State University.
- Natural Ventilation For Freestall Dairy Barns Susan Wood Gay, Extension Engineer; Virginia Tech. Publication Number 442-763, Posted December 2002
- Ventilation and Cooling Systems for Animal Housing by Scott Sanford, Senior Extension Specialist, University of Wisconsin, gives an overview of: box fans, high volume low speed fans, thermostats, sprikler systems, and variable speed fans.
- Ventilation for Warm Confinement Livestock Buildings Overview of ventilation requirments for different types of livestock, by Joseph M. Zulovich, Department of Agricultural Engineering, University of Missouri Extension.
Contributors to this Article
- Vern Grubinger, Professor, University of Vermont Extension