Mechanical Ventilation Systems in Greenhouses:

When natural ventilation in greenhouses is ineffective or unsuitable for agriculture, forced ventilation systems can be used. In this circumstance, fans are commonly used. The greenhouse's inside temperature can be adjusted via forced ventilation to match the outside temperature. This system ensures that high humidity levels are quickly removed from the greenhouse, particularly during sluggish weather conditions.

The advantages of forced ventilation are:

• Since it provides no positive air movement, moist air leaves from the plant, improving evapotranspiration and reducing risk of disease.
• The internal temperature of the greenhouse can be controlled more accurately.
• Smaller ventilation openings are required.
• The system can then be converted into an evaporative cooling system.
• Less labor requirements.
• Ventilation construction is unlikely to be damaged in stormy weather.

However, forced ventilation also has some disadvantages:

• Operation and maintenance costs are high.
• Special solutions may be needed due to the low ambient temperature, especially in winter.
• If not properly selected, ventilators can cause unwanted noise increase.
• During ventilation on high-irradiance days in winter or during transitional periods, cold outside air might enter the greenhouse directly during ventilation.