INDUSTRIAL GREENHOUSE CONSTRUCTION
Let's talk about the primary types of industrial greenhouses. It's relatively uncommon knowledge that due to their exceptional light transmittance and climatic stability, professional industrial greenhouses are typically constructed using glass.
The Netherlands holds a prominent position in greenhouse production and greenhouse equipment on a global scale. In the last ten years, advancements in greenhouse technologies have enabled a shift from energy-intensive to environmentally sustainable greenhouse practices. Collectively, Dutch greenhouses span an area exceeding 60 square kilometers, creating a glass city within the Westland region, which is also home to the PERSPEKTA company headquarters.
The wealth of Dutch history has contributed to the creation of three fundamental greenhouse models:
TRADITIONAL VENLO TYPE
The supporting framework of all greenhouse types includes columns, trusses, gutters, purlins, braces, connections, and connecting components.
This type is referred to as a "lightweight structure" because the load-bearing part is made of steel, and the material for securing the covering is aluminum.
The fundamental principle of greenhouse constructions is their dependability and long-lasting quality, which is guaranteed by accurate structural calculations for all external and internal pressures.
The greenhouse structures are typically crafted from cold-rolled profiles, which undergo galvanization through a hot-dip galvanization process. The steel structure comprises key elements, such as columns, trusses, beams, purlins, and braces.
The use of aluminum profiles helps to reduce the weight of the structure, secure the glass, manage rainwater drainage, and ensure the structural integrity of the construction. The aluminum structure includes profiles for glazing and connecting troughs.
The foundation of the greenhouse, known as the "construction," serves multiple purposes, including shielding plants from unfavorable weather conditions, facilitating the installation and operation of engineering systems, and ensuring the overall durability throughout its service life. The construction typically represents 10-25% of the total construction cost for a fully equipped greenhouse.
Among all greenhouse types, the Venlo greenhouse stands out as the most widely favored option. It offers a cost-effective solution compared to other types and can be tailored to meet your specific needs. These greenhouses are exceptionally sturdy and come with low operational expenses due to the combination of steel, glass, and aluminum.
The entire steel structure is fabricated with consideration for the internal greenhouse, wind, and snow loads specific to the region in which you plan to build. Each component is designed to be as lightweight as possible while adhering to structural standards.
The greenhouse is made up of a multi-span structure, which includes the following elements: columns, steel trusses, bracing, a white powder coating, aluminum gutters, and aluminum profiles.
The columns determine the height of the greenhouse with their own length. The optimal height of the greenhouse depends on the type of plants and the cultivation method. Today, we increasingly recommend greenhouse heights of 6.0m, 6.5m, and 7.0m. However, the choice can range from 4.5m to 12.0m. The columns of the greenhouse are constantly subjected to pressure.
Firstly, they bear the weight of the glass, aluminum roof, and internal greenhouse systems.
Secondly, greenhouse columns experience vertical loads as a result of wind suction.
Thirdly, the steel columns are subjected to horizontal loads due to the pressure exerted by the trusses affected by the wind.
In addition to the columns, the trusses create the framework of the Venlo greenhouse, serving as a structure to transmit all loads to the foundation. These steel trusses also serve as the support for internal systems like ventilation system, shading systems, hanging growing gutters, heating systems, steel wire, and any other systems as required by your project. The trusses themselves consist of four elements: the upper and lower chord profiles, diagonals, and end plates.
The span of the greenhouse is determined by the length of the truss, which is the distance between columns. The typical truss width is 8.0 meters, 9.6 meters, and 12.0 meters, with 8.0 meters being the most prevalent. Two ridges are located on a single span of this greenhouse. This greenhouse is offered as a versatile solution for both vegetable and flower producers.
To support loads at a 90° angle, columns and trusses alone are sufficient. However, loads can come from various angles, which is why bracing is incorporated into the structure. Their main role is to transmit horizontal forces along the gutters to the foundation.
White powder coating
All steel elements are always galvanized to prevent oxidation, giving the steel structure a gray appearance. Columns and trusses can be coated in white, which reduces light absorption and gives the greenhouse an unparalleled look.
Use of ALUMINUM PROFILES
The use of ALUMINUM PROFILES allows for a lighter frame, securing the glass, directing rainwater, and ensuring the overall structural strength.
A rubber gasket between the glass and aluminum enables a tight seal to prevent water and wind from penetrating the greenhouse. Similar to the steel structure, the aluminum system is designed to be lightweight and durable.
Glass panels are inserted directly into the aluminum gutter profile. Thanks to the sealing, the glass retains its function as a gutter even during heavy rainfall. In simpler terms, when there is a significant amount of rainwater, it moves upward along the glass towards the ridge but does not enter the interior of the greenhouse. This characteristic enhances the efficiency of the aluminum roof system.
The aluminum gutter not only collects rain and snow but also plays a significant structural role, providing strength. Additionally, the tray collects condensate water inside the greenhouse.
The profiles (glazing bars) used to secure the glass ensure maximum light transmission. For roofing, single-pane clear glass with a thickness of 4.0 mm is employed.
The side walls are typically glazed with single-pane glass. However, the system allows for the use of double glazing, polycarbonate, or sandwich panels as alternatives for covering.
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In terms of design, a wide-span greenhouse sets itself apart from a Venlo greenhouse due to its larger span width, roofing structure, and ventilation system. The span width in a wide-span greenhouse can reach up to 12 meters, and it typically features a single ridge running across the entire span. This larger span width results in a more substantial air buffer, contributing to a more favorable climate inside the greenhouse. Wide-span greenhouses are commonly utilized in applications such as garden centers and other architectural projects.
It's worth noting the primary drawback of this type is that it is much larger and heavier than the Venlo greenhouse.
The benefit of these types of greenhouses is a minimal amount of shading. This design provides almost limitless opportunities to fulfill specific needs for increased light and air circulation. Ventilation through uninterrupted windows ensures the maximum intake of fresh air. One-sided or two-sided window openings are particularly suitable for anti-mosquito screens.
The wide-span greenhouse is the ideal solution for many types of crops. The significant distance between columns provides more space for plants and automation.
Width of the span up to 16.00 meters
Height of the column up to 12.00 meters
Ventilation up to 50% of the area
Single or double continuous ventilation
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Externally, when the ventilation windows are in the closed position, the cabriolet greenhouse appears identical to the Venlo type. However, the distinction becomes evident when the ventilation windows are opened. The aluminum roof can be FULLY OPENED.
The cabrio greenhouse was created with growers in mind who prioritize excellent ventilation and maximum light exposure. Essentially, it features a unique roof that is installed on an adapted Venlo-type supporting structure. This setup provides growers with a wide range of options to precisely adjust the climate to their specific requirements.
Instead of ventilating from the ridge side, the windows of the cabrio greenhouse are hinged to the gutter for opening. The main benefit of the cabrio greenhouse is the ability to condition and acclimate specific plants by exposing them to external weather conditions. When the windows are open, the greenhouse's climate aligns entirely with the external environment.