Greenhouse performance indicators
1. Light transmittance of greenhouse
Greenhouses are daylighting buildings, so the transmittance is a basic index to evaluate the transmittance of greenhouses. Transmittance is the percentage of the amount of light that penetrates into the greenhouse as compared to the amount of light outside. The transmittance of the greenhouse is affected by the transmittance of the greenhouse covering material and the shadow rate of the greenhouse skeleton. Moreover, the transmittance of the greenhouse also changes with the different solar radiation angles in different seasons. The light transmittance of greenhouse becomes the direct influence factor of crop growth and crop variety selection. In general, the terraced plastic greenhouse in 50%~60%, glass greenhouse in 60%~70% transmittance, solar greenhouse can reach more than 70%.
2. Thermal insulation performance of greenhouse
Heating energy consumption is the main obstacle of greenhouse operation in winter. It is a direct means to improve greenhouse production efficiency to improve greenhouse thermal insulation performance and reduce energy consumption. The heat preservation ratio of greenhouse is a basic index to measure the heat preservation performance of greenhouse. The temperature chamber insulation ratio refers to the ratio of the covering area of pervious to light material of the greenhouse with small thermal resistance and the total area of the same ground covered area of the greenhouse enclosure structure with large thermal resistance. The greater the heat preservation ratio, the better the heat preservation performance of the greenhouse.
3. Durability of greenhouses
The durability of greenhouses must be considered in their construction. The durability of greenhouse is affected by the aging resistance of greenhouse materials and the bearing capacity of greenhouse main structure. In addition to its own strength, the durability of transmittance is also reflected in the attenuation of the transmittance with the extension of time, and the attenuation degree of the transmittance is the decisive factor affecting the service life of the transmittance. General steel structure greenhouse service life in more than 15 years. It is required that the design of wind and snow load should meet a large load once in 25 years. Bamboo and wood structure simple greenhouse service life of 5~10 years, the design of wind, snow load in 15 years to meet a large load.
Because the greenhouse is in high temperature and high humidity environment for a long time, the surface anti-corrosion of components has become one of the important factors affecting the service life of the greenhouse. Steel structure greenhouse, the main structure of the force is generally used thin-walled steel, its corrosion resistance is poor, in the greenhouse must use hot dip galvanized surface anticorrosion treatment, coating thickness of 150~200 micron above, can guarantee the service life of 15 years. For wood structure or steel welded truss structure greenhouse, must ensure that once a year surface corrosion treatment.