Greenhouse construction chooses sunny, sheltered, high-drying, well-drained, no place where the soil infectious disease hangs performance characteristics Temperature conditions Plastic film has insulation. After covering the film, the turbidity in the greenhouse will increase as the outside temperature rises and fall as the outside temperature falls. There are obvious seasonal changes and large temperature differences between day and night. The longer the temperature difference is, the greater the temperature period is. Generally in the cold season, the daily temperature can reach 3-6°C in the greenhouse, and it can only increase 1-2°C in the cloudy or nighttime. During the spring season, the temperature difference between the shed and exposed areas gradually increases, and the temperature can reach 6-15°C. When the outside temperature rises, the temperature of the shed meat increases relatively. The maximum temperature can reach above 20°C. Therefore, there is a high temperature and freezing hazard in the greenhouse. Manual adjustment is required. In the high temperature season shed can produce high temperatures above 50 °C. Ventilate the whole shed, cover the grass outside the shed or build a "pergola", which is 1-2 °C lower than the open air temperature. In sunny winter days, the lowest temperature in the night can be 1-3°C higher than the open ground, and several families and the open field are the same on a cloudy day. Therefore, the main production season of greenhouses is spring, summer and autumn. Through the insulation and ventilation cooling, the temperature of the greenhouse can be maintained at 15-30°C.
The light transmittance of the new plastic film can reach 80-90%, but the light transmittance is reduced by 10-30% during the use due to dust contamination, adsorption of water droplets, and aging of the film. The lighting conditions in the greenhouse vary greatly depending on the season, weather conditions, coverage patterns (shelf structure, azimuth, size, etc.), film types, and the conditions of use of the old and new. The larger the greenhouse, the greater the difference in irradiance in the vertical direction within the shed, and the difference in irradiance between the upper floor and the ground in the shed is 20-30%. In the winter and spring seasons, the lighting conditions of the greenhouses extending in east and west areas are better. It is better than the lighting conditions in greenhouses extending from north to south. The local lighting conditions are almost the same. However, the irradiance in the north and south of the extended greenhouse can reach 10-20%. Different shed structures have a great influence on the light receiving in the shed. Although the double-layer film covers better insulation performance, the light receiving conditions can be reduced by about half compared to the sheds covered by single-layer films. In addition, the connecting sheds and the use of different building materials also have a great influence on light reception (Table 4-2-3). From the table, it can be seen that the single shed steel and plastic-molded sheds received better light, and they only reduced the light transmittance by 28% compared to the bare ground. Townhouses suffer from poor light conditions. Therefore, materials used in building sheds should be able to use lightweight materials and simplify structures when they can withstand certain loads. They can neither affect light reception nor be sturdy and economical. Table 4-2-3 Light receiving capacity of different shed structures Greenhouse type Transmitted light Lux (10,000) Transmittance (%) Single-story steel structure Single-story bamboo-wood structure Single-story rigid-plastic structure Connected-section steel-and-concrete ground exposed control 7.67 6.65 7.65 5.99 10.6472.0 62.5 71.9 56.3 100 The film will greatly reduce the light transmittance due to dust contamination during the coating period. After two days of use of the new film, dust contamination will reduce the light transmittance by 14.5%. It will decrease by 25% after 10 days and below 28% after half a month. Under normal circumstances, the light transmittance can reduce the light transmittance by 10-20%. When severely polluted, the amount of light received in the shed was only 7%, resulting in an unusable level. The general film is also easy to absorb water vapor, condense into water droplets on the film, so that the light transmittance of the film is reduced by 10-30%. Therefore, it is an important measure to prevent the contamination of the film and prevent the condensation of water droplets. In addition, during the use of the film, the film is "aged" due to the effects of high temperature, low temperature, and ultraviolet rays of sunlight. The light transmittance of the film decreases by 20-40% after aging, and even loses its use value. Therefore, films covered by greenhouses should use long-life films that are resistant to temperature, ageing, and dust, so as to enhance light reception, increase temperature, and extend the service life.
Mainly depends on what you use, vegetables and fruits? Is it a plastic sheet? Also divided into different categories, how long do you want to use? Longevity film, drip film, daylight film...
There are special films: leafy special film, nursery special film, tomato special film, strawberry special film, pepper special film, single drop film, flower special film, rose special film......
The light transmittance of the new plastic film can reach 80-90%, but the light transmittance is reduced by 10-30% during the use due to dust contamination, adsorption of water droplets, and aging of the film. The lighting conditions in the greenhouse vary greatly depending on the season, weather conditions, coverage patterns (shelf structure, azimuth, size, etc.), film types, and the conditions of use of the old and new. The larger the greenhouse, the greater the difference in irradiance in the vertical direction within the shed, and the difference in irradiance between the upper floor and the ground in the shed is 20-30%. In the winter and spring seasons, the lighting conditions of the greenhouses extending in east and west areas are better. It is better than the lighting conditions in greenhouses extending from north to south. The local lighting conditions are almost the same. However, the irradiance in the north and south of the extended greenhouse can reach 10-20%. Different shed structures have a great influence on the light receiving in the shed. Although the double-layer film covers better insulation performance, the light receiving conditions can be reduced by about half compared to the sheds covered by single-layer films. In addition, the connecting sheds and the use of different building materials also have a great influence on light reception (Table 4-2-3). From the table, it can be seen that the single shed steel and plastic-molded sheds received better light, and they only reduced the light transmittance by 28% compared to the bare ground. Townhouses suffer from poor light conditions. Therefore, materials used in building sheds should be able to use lightweight materials and simplify structures when they can withstand certain loads. They can neither affect light reception nor be sturdy and economical. Table 4-2-3 Light receiving capacity of different shed structures Greenhouse type Transmitted light Lux (10,000) Transmittance (%) Single-story steel structure Single-story bamboo-wood structure Single-story rigid-plastic structure Connected-section steel-and-concrete ground exposed control 7.67 6.65 7.65 5.99 10.6472.0 62.5 71.9 56.3 100 The film will greatly reduce the light transmittance due to dust contamination during the coating period. After two days of use of the new film, dust contamination will reduce the light transmittance by 14.5%. It will decrease by 25% after 10 days and below 28% after half a month. Under normal circumstances, the light transmittance can reduce the light transmittance by 10-20%. When severely polluted, the amount of light received in the shed was only 7%, resulting in an unusable level. The general film is also easy to absorb water vapor, condense into water droplets on the film, so that the light transmittance of the film is reduced by 10-30%. Therefore, it is an important measure to prevent the contamination of the film and prevent the condensation of water droplets. In addition, during the use of the film, the film is "aged" due to the effects of high temperature, low temperature, and ultraviolet rays of sunlight. The light transmittance of the film decreases by 20-40% after aging, and even loses its use value. Therefore, films covered by greenhouses should use long-life films that are resistant to temperature, ageing, and dust, so as to enhance light reception, increase temperature, and extend the service life.
Mainly depends on what you use, vegetables and fruits? Is it a plastic sheet? Also divided into different categories, how long do you want to use? Longevity film, drip film, daylight film...
There are special films: leafy special film, nursery special film, tomato special film, strawberry special film, pepper special film, single drop film, flower special film, rose special film......
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