The venlo glass greenhouse is a kind of greenhouse that uses glass as the covering material. This kind of greenhouse is widely constructed all over the world due to its strong wind and snow resistance, strong environmental control ability and long service life. Because this type of glass greenhouse can cover dozens of acres of land alone, wall ventilation alone cannot meet normal ventilation requirements; therefore, it must rely on top ventilation to regulate and control.

Do a good job of natural ventilation in the greenhouse, which can remove excess heat in the greenhouse, prevent indoor high temperature, remove excess water vapor in the greenhouse, prevent excessive indoor humidity, maintain the CO2 concentration in the greenhouse, and reduce the harmful gas content in the greenhouse.

The principle of natural ventilation on the top of the greenhouse

Natural ventilation relies on the wind pressure caused by the outdoor wind and the thermal pressure formed by the temperature difference between the indoor and outdoor air to make the air flow to achieve the purpose of exchanging indoor and outdoor air. The air expands by heat, increases in volume, decreases in density, and becomes lighter in mass, forming an upward movement; when it rises to a certain height, the air forms an accumulation, spreads around and sinks to the ground, replenishing the original heat lost air and forming convection... The volume of cold air shrinks, and after the high-altitude air sinks and supplements, the air around the high-altitude needs to fill the missing part; while the cold air shrinks, the density increases, and it will flow to the surrounding areas near the ground with slightly higher temperature, and the area with slightly higher temperature The air will rise to high altitude, supplementing the part lost by the cold air volume contraction caused by high altitude, forming convective motion.

venlo greenhouse top window style

1. Fully open at the top

Full-opening at the top is the most efficient way of ventilation. On the triangular iron girder frame on the top of the greenhouse, the drive system controls the opening and closing of the windows on the entire spire slope. This ventilation method has the highest heat exchange and ventilation efficiency and is installed at the same time. The design difficulty coefficient is the highest, and the subsequent maintenance cost is also the highest.

2. Continuous window opening system

This type of system is also a single-sided slope window opening, but it uses a fixed shaft at the top, and the rotation of the top shaft drives the opening and closing of half of the peaked window sash. The ventilation efficiency of this type of ventilation is slightly lower than the ventilation efficiency of the top full-opening, but the single window area is adjustable.

3. Continuous staggered window opening system

The window is located on a slope of the spire, and the drive system is installed at the bracket position of the girder, working along the truss beam (span direction). When the window opening motor drives the drive shaft in one direction, it works by pushing the support rod fixed in the slideway of the window frame back and forth. The advantage of this type of window opening method of the venlo glass multi-span greenhouse is that the windows can be opened according to their actual needs and the main local wind direction. This method of top opening is widely used in the greenhouse industry. One way.