3rd International Poultry Meat Congress

How Ventilation Works
In simplest terms, ventilation means moving outside air into the house, and exhausting inside air
out of the house. Ventilation is a continuing, daily essential in poultry production throughout the
year. However, winter and summer ventilation requirements are very different. Ventilation needs
also change according to the age of the birds.
Key Factors: Air Exchange Rate and Air Flow-Through Pattern
The amount of air your ventilation system needs to move into and out of the house depends on
outside weather conditions and the age of the birds. Generally, the warmer it is and the larger the
birds are, the more air the ventilation system needs to move. You need the proper air exchange
rate for whatever conditions exist at the time. You might need to completely change house air on
average once a minute or even less, or every five minutes or ten minutes, or longer. In a house
using exhaust fan ventilation, the installed fan capacity in cubic feet per minute determines
the maximum possible exchange rate; in a naturally ventilated house, outside wind conditions
determine the maximum air exchange rate.
Also, the type of airflow pattern created in the house can make a critical difference. The most
important decision is whether we need to protect the birds from chilling by keeping outside air
from flowing directly onto the birds; or the flock needs the accelerated heat removal and windchill
effect of flowing outside air directly onto them. The number, size, and placement of inlets;
the incoming air velocity; the way outside and inside air are mixed; and the velocity and path of
the air stream through the house all need to be matched to the needs of the birds.
Depending on the age or size of the birds and the outside air temperature, getting the right
mix of air exchange rate and airflow pattern typically requires choosing one of three common
ventilation scenarios:
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