Ventilation is important in animal structures for temperature and relative humidity control and for removal of gases, dust, odors, and pathogens. The purpose of this fact sheet is to provide explanation of the technical side of inlet design and function while providing a glimpse of the art involved in inlet adjustment. Negative pressure or exhaust ventilation is common in animal housing and will be described here.

This fact sheet explains how to select an agricultural ventilation fan for the conditions under which it will be operating in a livestock or greenhouse setting.

Greenhouse barns are blossoming across the landscape. This fact sheet recommends design features to use for proper ventilation of a greenhouse barn. Effective natural ventilation design uses openings positioned both high and low in the structure, large openings for summer heat removal, unobstructed air flow inside the building, and location at a windy site.

This fact sheet explains how to improve ventilation in animal buildings through a self-adjusting baffle inlet.

This fact sheet explains how adding a second and third large baffle inlet assembly to a 50-calf room can provide hot weather ventilation.

In a well-managed ventilation system, the desired air speed exiting ceiling inlets is 800 to 1,000 feet per minute (fpm). The handy air speed monitors described here are a cheap, easy, and adequate way to estimate air speed.

Ammonia gas concentration is almost impossible to determine without using an instrument. Our human nose will not recognize ammonia until about 20 to 30 parts per million(ppm) has been reached. Farmers who have frequent exposure to livestock facilities with recognizable ammonia gas levels are known to lose their sensitivity to smell ammonia gas concentration. Even the casual visitor to an animal facility will acclimate to an ammonia odor within about 20 minutes. Fortunately easy-to-use and relatively inexpensive instruments are available for measuring ammonia level in animal environments (dairy, swine, beef, veal, poultry, dog kennel, horse, etc.). Highly accurate and sophisticated instruments are also available at greatly increased cost.

A psychrometric chart presents physical and thermal properties of moist air in a graphical form. It can be very helpful in troubleshooting and finding solutions to greenhouse or livestock building environmental problems. This fact sheet explains how characteristics of moist air are used in a psychrometric chart. Three examples are used to illustrate typical chart use and interpretation.

Tie stall barns require a ventilation system that allows close control of air exchange and temperature to prevent the barn from reaching freezing temperatures.

Cows continuously produce heat and moisture. When cows are confined in freestall barns, loafing sheds or under shade structures, a ventilation system is necessary to continuously exchange warm, humid inside air for drier, cooler outside air.