The corridor, located on the outer gable of the greenhouse, uses outside air for dehumidification and cooling. Thus, the corridor is used to mix inner air with external air. This phenomenon represents the air treatment of semi-closed greenhouses, mostly used for Venlo glass (Kubo, Van der Hoeven, Richel…) and plastic (CMF, Richel…) ones.
How to design a semi-closed greenhouse ?
1. What is a semi closed greenhouse ?
This system aims to :
-dehumidify the atmosphere of the greenhouse by renewing and drying out the air inside, due to outdoor air (during the night and in the morning)
-cool dry inner temperature with pad cooling system, on external side of the corridor
-reduce the amount of harmful insects, thanks to overpressure.
-control the climate of the greenhouse avoiding the gap of temperatures
-optimize the use of energy and CO2
Heating system is composed of :
-air ducts below crops’ gutters for the diffusion of warm/cold air.
-low temperature network (30-40°C) placed in in vegetation
-high temperature network (70-80°C) placed on the ground to ensure heating.
Cooling system could be composed of :
-pad and fan system using evaporative cooling
-fog system using evaporative cooling
2. Semi-closed greenhouse design in Hortinergy
The semi-closed greenhouse model includes :
- Climate control
The model implements the following equipements :
- Controlled external ventilation for dehumidification,
- Air recirculation in tubes,
- Electricity energy consumption of fans,
- Adiabatic cooling with fog or pad system.
Crop evapotranspiration is modelled with climatic parameters as well as type and development of the crop. The climatic parameters are temperature, relative humidity, solar radiation, inner air velocity…
3. Outputs of semi-closed greenhouse design
Hortinergy provides a comprehensive analysis of the :
- Hourly inner climate,
- Energy, electricity and water consumption.
We show the results of a semi closed greenhouse located in South France. The climate is hot and dry climate. A pad system performs cooling and dehumidification.
Cooling temperature set : 26°C
Results are temperature, relative humidity, hydric deficit and solar radiation in the greenhouse.
In this example, we show the results during a typical day of July.
The inner temperature is never above 26°C. Hydric deficit is between 2 and 4.5 g/ kg da.
Results also provides the external air flow, water flow and evapotranspiration.
During night time and morning, fans can blow the external air in the greenhouse to dehumidify.
Then, during day time, pad cools the greenhouse.
Hortinergy shows also heating, electricity and water consumption. You have access to an annual overview, a monthly synthesis and hourly data.
Annual overview of the energy consumption.
Monthly synthesis of the energy consumption.
Hourly data of the energy consumption
4. Model validation
Model is being under validation with 2 semi-closed greenhouses in France. They are located in CTIFL in Carquefou (wet climate) and Balandran (dry climate).
Hortinergy is an online paid software. You can choose your offer, create an account and then start your project.