A calculation-based approach to choosing farm fans

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A calculation-based approach to choosing farm fans

When discussing farm or livestock-house ventilation, some people think an open building or roof ventilation turbines are enough. But conditions and Thailand's hot seasons change, so equipment called a   farm fan or ventilation fan   is used to blow or extract air from the building. Which type should you use and how should you choose it? Consider the following.

• For an enclosed building, install both air supply and extraction.
• For a farm with existing air circulation, extraction alone may be used.
• Consider the direction of airflow inside the building. Position the ventilation fan at the side where air enters the room, as described by the source.

If air can be extracted directly through that wall, use a wall-mounted unit. Otherwise, the source suggests a ceiling-mounted unit.

• Finally, here is the calculation method presented in this article.

Calculating the size or model of a ventilation fan   based on the room's air volume:

Building volume = width x length x height (in metres)

Required airflow, or CMH = room volume x standard factor - CMH = cubic metres per hour. It can be converted to cubic feet per hour, or CFH by multiplying CMH by 35.32 or from an hourly to a per-minute unit by dividing by the appropriate factor, which is not provided in the original text. The standard factor refers to the required air change rate for each building type.