How to design ventilation openings in solar greenhouse?

The improved solar greenhouse is generally equipped with two rows of vents. The upper vent hole is located at the top of the greenhouse, generally about 50 cm wide, and it is opened by peeling the film downwards, or covering a narrow film with a width of about 1.5 m, and pulling the film upwards when it is opened, as shown in Figure 17. In order to facilitate the management of vent holes, protect the film and reduce damage. At present, the latter form is mainly used for large-scale improved solar greenhouses, while the former form is mainly used for some small greenhouses with small width and less ventilation. In order to protect the film, the lower edge of the film at the vent should be reinforced with iron wire. It is best to reinforce the iron wire with special steel wire. With the elasticity of the steel wire, the lower edge of the film is kept straight, and the closing quality of the upper and lower films is improved. The upper edge of the film is pressed against the rear roof.

The traditional solar greenhouse generally does not have a vent, but the lower edge of the film is lifted and rolled up to replace the vent. When the wind is released, it clings to the ground and enters the greenhouse in the form of "sweeping the wind". Cold air blows directly on the ground, and the ground cools quickly, which is easy to hurt the roots of plants. Most modern solar greenhouses are specially equipped with lower vents, and the vent line is 1 ~ 1.5 meters high from the ground. When breathing, push the membrane upward to expose the seam for breathing, as shown in Figure 17. Specially designed vents are located at a higher position, so cold air will not blow directly on the ground during ventilation, which has little adverse effect on the roots, and at the same time, the cooling effect is improved because of the high position.

Fig. 2 1 vent layout and form of improved solar greenhouse a, upper vent b, lower vent 1, iron wire longitudinally fixed on membrane 2, membrane 3, arch shape.