Main types of greenhouses

Greenhouses are a type of greenhouse, mainly to maintain a certain temperature, also known as a greenhouse. The types of greenhouse greenhouses are mainly plastic greenhouses, glass greenhouses and solar greenhouses, which are described below.

Plastic greenhouse

Compared with the glass greenhouse, it has the advantages of light weight, less amount of skeleton materials, low shading rate of structural parts, low cost, long service life, etc. Its environmental control ability can basically reach the same level of glass greenhouse, and plastic greenhouse users accept The ability is far higher than the glass greenhouse in the world, becoming the mainstream of modern greenhouse development.

The main structure of the plastic greenhouse must have at least 8 wind resistance, and generally require a wind resistance of 10 grades.

The snow load carrying capacity of the main structure shall be determined according to the actual snowfall conditions in the construction area and the winter use of the greenhouse. For use in the north, the design snow load should not be less than 0.35kN/m2.

For annual operating plastic greenhouses, consideration should also be given to a number of load factors such as equipment weight, plant hoisting, maintenance, etc.

Glass greenhouse

A glass greenhouse is a greenhouse in which glass is a transparent covering material. In the basic design, in addition to meeting the strength requirements, it should have sufficient stability and resistance to uneven settlement. The foundation connected with the inter-column support should also have sufficient horizontal force and space stability. The bottom of the greenhouse should be below the frozen soil layer. The heating greenhouse can consider the influence of heating on the base freezing depth according to the climate and soil conditions. Generally, the bottom of the foundation should be lower than 0.5 meters above the outdoor ground, and the distance between the top surface of the foundation and the outdoor ground should be greater than 0.1 m to prevent the foundation from being exposed and adversely affecting cultivation. Unless otherwise specified, the distance between the top surface of the greenhouse foundation and the indoor floor should be greater than 0.4 meters.

The design of China's glass greenhouse steel structure is mainly based on the greenhouse design specifications of countries such as the Netherlands, Japan and the United States. However, structural strength, structural rigidity, structural integrity, and structural durability must be considered in the design.

Solar greenhouse

The front slope is covered with heat insulation at night, and the east, west and north sides are single-slope plastic greenhouses with enclosed walls, collectively referred to as solar greenhouses. The prototype is a single-slope glass greenhouse, and the light-transmissive covering material on the front slope is replaced by a plastic film instead of glass, which evolves into an early solar greenhouse. The solar greenhouse is characterized by good insulation, low investment and energy conservation, which is very suitable for the use of underdeveloped rural areas in China.

The light transmittance of energy-saving solar greenhouses is generally above 60% to 80%, and the indoor and outdoor temperature difference can be maintained above 21-25 °C.

The solar greenhouse is mainly composed of three parts: the wall, the rear roof and the front roof. It is referred to as the “three elements” of the solar greenhouse. The front roof is the whole lighting surface of the greenhouse. Before the daylighting period, the roof is covered with plastic film only. When the light is weakened, the plastic film is covered with active insulation in time to enhance the insulation of the greenhouse.