What are the ventilation methods for glass greenhouses?

Glass greenhouse ventilation is to remove the waste heat and humidity in the greenhouse, adjust the air composition in the greenhouse, so that the ambient temperature, humidity and air in the greenhouse meet the growth needs of plants.

1. Natural ventilation

Many times, glass greenhouses use natural ventilation to regulate indoor temperature. The glass greenhouse structure is generally a double-slope multi-span greenhouse, and the form of ventilation is to install ventilation windows on the side walls and the roof. The total ventilation area is not less than 15% and not more than 30% of the greenhouse area. When the roof wind window is opened, the window sash can be inclined upward beyond the horizontal plane, and when it is fully opened, it forms an angle of 100° with the horizontal plane to obtain a good ventilation effect. The amount of natural ventilation is related to wind speed, wind direction, position of ventilating window, area of ventilating window and temperature difference between inside and outside the greenhouse.

2. Forced ventilation

Although the glass greenhouse relies on natural ventilation to adjust the environment most of the time, when the summer temperature is high, especially when the outdoor temperature exceeds 33°C, it is difficult to meet the cooling requirements of the greenhouse by natural ventilation alone. At this time, measures such as forced ventilation are required to cool down. Forced ventilation is the use of fans to convert electrical or other mechanical energy into wind energy, forcing air to flow, and ventilating the greenhouse to achieve a cooling effect. The theory of forced ventilation is that indoor air temperature is equal to outdoor air temperature. It is impossible in actual application. Due to mechanical equipment and plant physiology, the ventilation intensity of a general greenhouse is 0.75 to 1.5 times per minute, and the temperature difference between inside and outside the greenhouse can be controlled within 5°C.