Ventilation System

Mechanical and natural ventilation are used in all types of swine buildings. Mechanical ventilation is commonly used in farrowing and nursery buildings where temperature control and heating energy costs are important. Natural ventilation can be used for farrowing and nursery buildings, but is more common for gestation, breeding, and finishing facilities.

The purposes of any swine facility ventilation system are to: (1) maintain an adequate supply of fresh air for the animals, (2) remove excess moisture during cold weather, (3) remove combustion gases from heaters, (4) provide adequate temperature control during mild weather, and (5) limit the temperature rise during hot weather. The major carriers of odors are: gases from manure, dust, and water vapor. A well designed and managed ventilation system will control the levels of all three of these and is a major factor in controlling odors from swine buildings.

A practical and objective way of evaluating the effectiveness of a ventilation system for odor control and indoor air quality is to take gas measurements during cold weather. That is, at minimum airflow conditions. Carbon dioxide and ammonia are the two most important gases to measure. Carbon dioxide concentrations are set by the ventilation rate and the number of animals in the building. Ammonia concentrations are influenced by both the ventilation system and the waste system. If the concentration of these gases are at or below recommended levels then other gases are typically within recommended levels. Recommended concentrations of some of the most important gases in swine buildings are shown in the following table.

Recommended Gas Concentrations for Odor Control in Swine Buildings

Gas	Odor	Recommended Maximum Concentration
Carbon Dioxide	None	3,000 ppm
Ammonia	Sharp, pungent	15 ppm
Hydrogen Sulfide	Rotten egg smell	3 ppm
Carbon Monoxide	None	50 ppm

The required summer ventilation rate is at least 10 times greater than the minimum continuous rate. Therefore, gas concentrations within the building are often minimal during the summer in a properly designed facility.

Return to Management of Odor and Sources Return to Odor Control Return to The Land Application of Animal Manure.