Calculating how much ventilation you need

2 minutes reading

Ventilation fans in the side of a poultry barn

Ventilation allows you to refresh the air in a room over a period of time. Are you ventilating too much? Then you're using an unnecessary amount of energy to run fans and possible heating costs. Are you ventilating too little? Then an unhealthy or unpleasant indoor climate can result. But how do you determine the right amount of ventilation? There are, basically, three calculation methods to determine the desired amount of ventilation per unit of time.

Ventilation rate

Depending on the application, a certain ventilation rate is recommended. The ventilation rate indicates how often the room is supplied with fresh air per hour. For this you need to know the volume of the room (height x width x length = volume in m3 or ft3). The ventilation per hour is then calculated as follows: volume x ventilation rate = m3/hour or cfm.

Geared to (poultry) livestock

Authorities such as animal specialists or the government indicate how much fresh air should be supplied and dirty air removed per live animal weight per hour. Does the weight of the animals change? Then the amount of ventilation also changes. To determine this, we look at:

  • Number of animals
  • Weight per animal
  • Desired amount of air per kg per hour in cubic meters

    With this information you can easily calculate the total amount of ventilation:
    Number of animals x weight per animal in kg x desired amount of air per kg per hour = m3/hour. 

Air speed

Finally, you can calculate the amount of air based on the desired air speed. This is usually given in meters per second. Moving air at a high speed (usually 2 to 3 m/s) creates a wind chill effect. The wind chill effect means that it feels cooler in the wind compared to outside wind, while not lowering the temperature. To calculate this, you need the following data:

Area of the cross-section of the room (width x height) in square meters
Desired air velocity in meters per second

Then you calculate this as follows:
Width (m) x height (m) x desired velocity (m/s) x 3,600 = m3/hour

Calculating it yourself

Each method is used for a different situation. Is it about refreshment of air to remove certain gases or moisture? Then choose method 1. Is it for a (poultry) barn where a desired amount of air per kg is advised? Then choose method 2. Is it a warm environment where a wind chill effect must be created? Then choose method 3.

Would you like advice for your specific situation? Feel free to contact our customer service department.

Share with others

Picture of Vostermans Ventilation
published on March 17, 2023

Vostermans Ventilation

Go back

Talk to one of our specialists.

We like to think along with you.

Contact now