Many kinds of agricultural applications require ventilation. Animals need fresh air, and manure and wet bedding can produce airborne pathogens which must be removed by fans. Appropriate temperature and humidity control can also be accomplished with a suitable ventilation system. This is necessary since heat stress is a major cause of unhealthy or unproductive animals.

Despite wider awareness of the importance of ventilation, it still happens that misconceptions about the requirements result in suboptimal ventilation conditions. Changing weather conditions and increased animal numbers and sizes are not the only influence on airflow and air velocity needs. Fan selection and installation as well as barn placement and design are oft-misunderstood aspects of a well-functioning ventilation system.

Fan accessories such as shutters and guards are necessary elements of the ventilation system. Guards ensure safety, while shutters ensure that airflow and static pressure are not unduly affected when a particular fan is not operating. However, these accessories reduce the airflow capacity of operating fans to below the rating of the free fan. Poor inlet placement and windbreaks can also lead to reduced airflows.