Semi-closed plastic greenhouses represent one of the most advanced and efficient solutions in modern protected agriculture. This type of structure combines the use of advanced technologies to control the climate, optimize resource consumption and improve crop production. In this post, we will explore what a semi-closed plastic greenhouse is and, in detail, how its air recirculation cooling system works, a key feature in places with hot and dry climates.
What is a semi-closed greenhouse?
A semi-closed greenhouse is different from traditional models due to its ability to manage and optimise the internal climate more precisely and efficiently. Semi-closed greenhouses employ an advanced control system that regulates air intake and output, temperature, humidity and carbon dioxide (CO2) levels. This is achieved through the use of fans, cooling systems, distribution sleeves and a particular structure that includes a corridor attached to the greenhouse.
The main objective of a semi-closed greenhouse is to maximise energy efficiency and improve control over internal environmental conditions, minimising energy and water losses. This type of greenhouse allows cultivation in a more controlled environment, which favours sustainable production and resource savings. Semi-closed plastic greenhouses, in particular, offer an effective solution in extreme climates, very dry or with large temperature variations.
How does the air recirculation cooling system work?
The operation of the air recirculation cooling system in a semi-closed plastic greenhouse is a complex, but highly efficient process. Below we break down the key steps:
- Outside Air Intake
The process begins with outside air entering the greenhouse. This air enters through specially designed windows that are connected to a passageway that runs along the front of the greenhouse. Unlike conventional greenhouses, where the air enters directly into the greenhouse, in semi-closed models the air first passes through a control system that regulates its temperature and humidity.
- Cooling System
Once outside air has entered the greenhouse, the cooling system reduces its temperature through evaporative cooling, which also increases humidity. It is then distributed throughout the space. This cooling process is essential to maintain an adequate temperature inside the greenhouse, especially in hot, dry climates or during the hottest months of the year.
The cooling system works by using cold water or refrigerants that lower the temperature of the air as it passes through cooling pads or devices. This process ensures that the air circulating inside the greenhouse is at the right temperature for the plants, which helps prevent heat stress and promotes more uniform and healthy growth.
- Distribution of cold air through air sleeves
Once cooled, the air passes through a ventilation system and is distributed through perforated sleeves located under the hydroponic cultivation systems. These sleeves are essential to ensure that fresh air reaches all parts of the greenhouse, even the plants furthest from the ventilation and cooling systems.
This distribution system ensures that there are no hot or cold spots inside the greenhouse, which can occur in larger structures without precise airflow control. In a semi-closed greenhouse, climatic conditions are kept uniform, which is key to optimal crop growth.
- Rising warm air
Cold air circulates throughout the greenhouse, maintaining a constant temperature, but as is normal, it ends up gradually warming up due to solar activity. This warm air tends to rise, following the principle that warm air is less dense and rises.
In semi-closed models, warm air is not immediately released outside, as in conventional greenhouses. Instead, it is directed towards an upper window that directs it back into the aisle, mixing with new air that has passed through the cooling system, lowering its temperature and returning to the greenhouse through the plants.
- Air recirculation
Once the warm air reaches the aisle, it is mixed with the air coming from outside that has passed through the cooling system, it is cooled again and redistributed throughout the greenhouse through the air bags. This recirculation process is one of the most innovative aspects of semi-closed greenhouses, as it allows the majority of the air inside the greenhouse to be reused, reducing the need for external ventilation and minimising energy loss and thermal changes in the plants.
Air recirculation not only improves energy efficiency, but also helps to maintain constant levels of humidity and CO2 inside the greenhouse, which is essential for optimal crop growth. In addition, this process creates a positive pressure inside the greenhouse, which makes it difficult for pests and diseases to enter, thus reducing the need for pesticides.
A semi-closed system like this keeps the greenhouse performing at a high level with much less air changes than a normal or traditional ventilation system (if you are interested in knowing more, write to info@jhuete.com).
Advantages of Recirculating Air Cooling System in Semi-Closed Greenhouses
Using a recirculating air cooling system in a semi-closed plastic greenhouse offers a number of advantages that make it an attractive option for farmers looking to maximize their production and reduce their resource consumption. Some of the key advantages include:
- Energy Efficiency: By recirculating air within the greenhouse, the need to constantly cool new air from outside is reduced, which decreases energy consumption.
- Precise Climate Control: The recirculation system allows for consistent temperature and humidity to be maintained throughout the greenhouse, which promotes even crop growth.
- Reduced Pesticide Use: Positive pressure within the greenhouse makes it difficult for pests to enter, reducing the need for chemical treatments.
- Improved Productivity: Optimal, consistent climate conditions within the greenhouse promote faster, healthier crop growth, which can increase production.
Semi-closed plastic greenhouses with cooling and air recirculation systems represent one of the most advanced and sustainable technologies in modern agriculture. By providing precise and efficient climate control, these greenhouses allow maximizing productivity, reducing energy and water consumption, and minimizing pesticide use.
For farmers looking for an innovative and sustainable solution, semi-closed plastic greenhouses are an excellent option to improve the profitability and sustainability of their production.
