The ventilation and circulation of air in horticultural greenhouses is crucial for the growth and well-being of plants. Depending on the situation in and around the greenhouse, various issues can arise with the indoor climate. These issues can often be resolved with the correct use of fans and ventilation. In this article, we will discuss common ventilation problems in horticultural greenhouses and what you can do to address them.
Ventilation or Circulation Issues?
First, it's essential to distinguish between ventilation and circulation. Ventilation involves exchanging air inside the greenhouse, while circulation ensures uniformity of the air within the space. Both are interconnected and play a key role in maintaining a healthy greenhouse climate.
Common causes of climate problems in horticultural greenhouses include:
- Insufficient or excessive ventilation
- Insufficient or excessive circulation
- Fan installation errors
- Greenhouse construction errors
Ventilation Issues
Moisture Problems
The ideal moisture content in a greenhouse depends on the type of crop and environmental conditions. High moisture levels can lead to fungal issues and plant diseases. Growers can maintain the desired moisture levels by using roof vents, dehumidifying equipment, or fans. Learn more in our article about the importance of a healthy greenhouse climate.
Temperature Problems
Temperature fluctuations—whether too high or too low—can adversely affect crops. In warm weather, growers can exhaust warm air through ventilation or use fans combined with pad cooling systems to draw in cooler outside air.
Ventilation Rate
Determining the ventilation rate is essential when installing fans. This involves calculating the greenhouse volume and the air exchange frequency required to maintain a healthy climate. An incorrect ventilation rate can negatively impact both the climate and crop health, requiring tailored solutions based on the location and crop type.
Circulation Issues
Uneven Distribution of Temperature and Moisture
For successful cultivation, a uniform indoor climate is essential. Circulation fans are commonly used to ensure uniformity. Disparities in temperature and moisture levels within a greenhouse can impact crops and increase energy costs. Common causes include:
Cracks or Leaks in Greenhouse Windows
Small leaks in greenhouse glass can create drafts or cold spots, especially in colder climates. Temperature measurements are often used to detect these issues.
Greenhouse Location
Uneven exposure to sunlight or wind can create cold or warm spots, even in intact greenhouses. Adjusting fan installation and settings can help mitigate these effects.
Heat Accumulation at the Top of the Greenhouse
Heat from sunlight, heating systems, or lighting can accumulate near the ceiling. Vertical circulation helps distribute this warm air evenly at plant level, improving uniformity and reducing heating costs.
Obstacles in the Greenhouse
Structures like trusses can locally cool the air, impacting the uniformity of the greenhouse climate.
Fan Installation Errors
Improper fan installation can cause circulation issues. For example, incorrectly connected fans may rotate in the wrong direction or be spaced too far apart, reducing airflow efficiency. Proper planning during greenhouse construction can address these challenges.
Circulation Rate Problems
Air speed is crucial for removing moisture from crops and creating a drier plant-level climate. The circulation rate, which measures how many times per hour air is circulated within the greenhouse, must be optimized for each crop type.
Get Expert Advice
Are you facing ventilation or circulation issues in your greenhouse? Interested in learning how fans can help? Contact one of our specialists for personalized advice tailored to your situation.
