Characteristics and principles of greenhouse construction

1. greenhouse is a special agricultural production facility

The greenhouse is formed by the foundation, the main frame structure, and the enclosure materials. The relatively closed main body and space of the building mainly play the role of carrying various loads, heat preservation, wind, rain and snow, etc.; the supporting facilities and equipment in the greenhouse further regulate the environmental factors such as temperature, light, water and air to improve and improve the function of the greenhouse. Form the overall supporting greenhouse facilities. The main body of the greenhouse building formed by the foundation, the main skeleton structure, and the enclosure materials of the greenhouse is a construction engineering problem; the production of the main skeleton structure of the greenhouse is similar to the mechanical processing product, and the supporting equipment is entirely mechanical product. Therefore, it can be said that the greenhouse is a comprehensive product combining construction and mechanical processing. Since the main body of the greenhouse building is a construction project, the whole process of its design, installation and construction must be carried out in accordance with the relevant standards, codes and regulations of the building; and the main frame of the production, installation and supporting equipment The selection and installation must be carried out in accordance with the standards, specifications and regulations related to mechanical products. For greenhouse construction, from a technical point of view, the overall plan design of the greenhouse, the construction of the greenhouse, the production of the main frame of the greenhouse, the selection of greenhouse covering materials and supporting equipment, the installation and commissioning of the greenhouse, and the use of the greenhouse Strict quality control in several major links such as management can ensure the overall quality of greenhouse construction. Greenhouse is a kind of agricultural production building with distinct functions, which is used for effective production Dedicated facilities. Therefore, before building a greenhouse, we must first clarify the use function of the greenhouse, that is to say, what is the purpose of building a greenhouse? In this way, the main performance indicators can be determined according to the requirements for the use of the greenhouse to meet the requirements for the use of the greenhouse. Greenhouses are different from general living facilities or supplies. According to different functions, greenhouse can be divided into different grades, which are formed by different structural forms, different covering materials, and different supporting equipment. Space environment with different performance indicators to adapt to the environmental requirements of different use functions. The different structural forms, different covering materials, and different configurations of the greenhouse make its use performance different. Of course, its construction and operating costs are also quite different. The reason why greenhouse construction must have a clear purpose is to appropriately determine the use function and performance index requirements of the greenhouse according to the purpose of use of the greenhouse, so as to determine the structure, covering materials, and configuration of the greenhouse And so on, and finally achieve the goal of meeting the use requirements with as little investment as possible. Of course, this is to avoid the unreasonable phenomenon of “large horse-drawn cart” or “small horse-drawn cart” after the completion of the greenhouse, that is, to avoid waste of investment or fail to meet the use requirements most effectively. Greenhouses have strong regional adaptability and are largely restricted by local climatic conditions and are related to climatic conditions Very close. my country is a large country that spans several climatic zones, and it is also a country with a strong continental and monsoon climate. The climates of the east, west, south and north are very different. In terms of crop cultivation, the selection of various varieties, Cultivation patterns are extremely different. Over the past 30 years of my country’s reform and opening up, the construction of greenhouse has developed rapidly and has made great progress. However, the introduction of greenhouse technology and facilities, especially in the construction of large modern multi-span greenhouse, also has a certain degree of blindness, which must be paid attention to. . Therefore, greenhouse construction must be adapted to local conditions. From the perspective of the actual production process in the greenhouse, it has a great relationship with several environmental factors such as light, temperature, air, water, and soil, and greenhouse facilities are to create these environmental factors for crops. For greenhouse production, the two most important environmental factors are light and temperature. If light and temperature cannot meet the requirements for crop growth, there is no need to build a greenhouse. Especially in areas with poor lighting resources in winter and spring, it is not suitable to develop greenhouse. Of course, light supplement measures can be taken, but the measures of supplement light cycle are practical and effective, and the measures of supplement light intensity are too much energy consumption. It is often economically uneconomical and should be carefully considered. Greenhouse heating is a very common and necessary measure. In the Yangtze River Basin and its south, the heating time is short and the amount of supplementary heating is small. The heating cost in winter and spring accounts for about 20% and 30% of the total operating cost. The effect of temperature is significant; theoretically, the Huanghuai Basin is the most suitable for the development of greenhouse production, and the cost of supplementary heating accounts for about 30% and 40% of the total operating cost, and its input and output ratio is cost-effective; in the northeast and northwest of the high cold In regions, the general supplementary heating cost accounts for about 50% and 60% of the total operating cost. Normally, it is not cost-effective. It is feasible if the value of the products in the greenhouse can be increased. In greenhouse construction, local wind, snow load and geological conditions are also important factors, which can be adapted to it through scientific design and rigorous construction. Greenhouse construction should also consider factors such as the product market and production technology management of greenhouse production. The product market for greenhouse production is, in the final analysis, the key to greenhouse production. Necessary investigations and studies must be conducted before greenhouse construction; greenhouse production is an industry with high technological content, and it is not equivalent to the transplantation of general field cultivation techniques. The training and preparation of relevant technical personnel is also very important. The construction and use of greenhouse is an engineering problem. In view of the distinctive functionality and comprehensiveness of the greenhouse, the integrity and supporting nature of the greenhouse are particularly important. For the current greenhouse enterprises and greenhouse users in my country, it is necessary to pay special attention to and strengthen the overall concept and awareness of the integrity and supporting of the greenhouse. The integrity and matching of the greenhouse mentioned here have two meanings. One is that the greenhouse itself must form a complete whole and complement each other; the other is that the greenhouse must be closely related to environmental engineering and biotechnology. Combine to form a complete and complete overall concept. The greenhouse is composed of the foundation, the main frame structure, and the enclosure materials to form a relatively closed building body and space; the supporting facilities and equipment of the greenhouse are used to regulate the temperature, light, water, air and other environmental factors in the greenhouse to form Overall supporting greenhouse facilities. Therefore, all parts and links are closely related and inseparable from the design of the overall greenhouse plan, infrastructure construction, production of main skeleton components, selection of covering materials and supporting equipment, installation, and debugging. Throughout the process, there must be a sense of holistic and complementary concepts, and strictly follow the relevant regulations to ensure the overall quality of the greenhouse. The greenhouse is an agricultural production facility, and it cannot be treated as an isolated issue. Greenhouses must be closely integrated with environmental engineering and biotechnology (including selection of special varieties for crop cultivation, cultivation management techniques, etc.) to form an overall concept in order to form an effective production capacity, generate economic benefits, and achieve sustainable development. At present, my country's greenhouse and greenhouse users and practitioners have such a weak sense of overallity and complementarity, which is the fundamental reason why my country's facility horticulture industry lags behind developed countries. Greenhouse production is carried out under unfavorable natural environmental conditions, so it is a kind of high resistance Energy-consuming industries. For greenhouse production, saving energy and improving energy utilization are important ways to reduce greenhouse production costs and improve greenhouse production efficiency. Energy saving is also very important for reducing resource consumption, protecting the environment, enhancing the vitality of the greenhouse and facility horticulture industry, and ensuring the sustainable development of facility horticulture production. Therefore, t greenhouse energy saving is an eternal research topic in greenhouse. From the entire process of greenhouse construction site selection, greenhouse design, greenhouse construction and greenhouse use, there must be a clear concept of energy saving, and corresponding energy saving technologies and measures must be adopted. When selecting a greenhouse site, considering the large area and the specific construction site, its natural resource conditions, mainly light and heat resources, wind and snow loads, water sources, and traffic conditions, should be conducive to Energy-efficient production of greenhouse. In the greenhouse design, special attention should be paid to the application of energy-saving technologies, mainly the reasonable selection of heating methods and the improvement of energy efficiency; under the condition of ensuring the requirements of light transmittance, use light-transmitting covering materials with high thermal insulation performance; as far as possible Natural ventilation cooling method is adopted to reduce cooling energy consumption, so that the greenhouse can run at low cost in summer; heat preservation and sunshade screen with dual functions of heat preservation and sun protection are adopted. In greenhouse construction, we must pay attention to energy-saving measures, such as the surrounding heat preservation treatment during infrastructure construction, the treatment of cold bridges formed by exposed steel structures and aluminum alloys, etc.; special attention must be paid to improving the airtightness of the greenhouse to reduce energy loss caused by cold wind penetration . In the use of greenhouse, energy-saving measures are also very important. First, we must choose high-yield and high-quality varieties with strong resistance to fundamentally reduce energy consumption; adopt measures such as greenhouse temperature change management and crop root zone heating to ensure crops Normal growth can reduce energy consumption; reasonable planning and layout, adopting large and small row spacing and reasonable dense planting, 4 and adopting movable cultivation beds and three-dimensional cultivation measures to improve the utilization rate of greenhouse ground; adopt appropriate greenhouse management and regulation methods, Use the greenhouse correctly to prevent energy loss caused by improper regulation and use.