covering materials; PE or PVC
covering materials are more or less common to all system, from mulching to greenhouses. glass has been the traditional and ideal covering material for many years, and it still is, if the facility is designed for year-round use. when farmers insist on investment in a shorter period of time or use the facility for only a certain part of the year , soft films are used. the three covering films most often used are PVC, PE and EVA(Ethylene Vinyl Acetate). PVC is the most opaque to long wave radiation(second only to glass); next most opaque is EVA, and then PE at the same thickness. PE is the most transparent to long wave radiation; often the inside air temperature of a PE house can be lower than the outside due to long wave radiation loss on clam, clear winter nights. the few degrees' difference between a PVC and a PE house is critical if the house is not heated and the temperature is around the freezing point. now that IR-resistant PE and EVA have been developed, the difference can be minimized.the characteristics of long wave transmissivity
covering materials; PE or PVCcovering materials are more or less common to all system, from mulching to greenhouses. glass has been the traditional and ideal covering material for many years, and it still is, if the facility is designed for year-round use. when farmers insist on investment in a shorter period of time or use the facility for only a certain part of the year , soft films are used. the three covering films most often used are PVC, PE and EVA(Ethylene Vinyl Acetate). PVC is the most opaque to long wave radiation(second only to glass); next most opaque is EVA, and then PE at the same thickness. PE is the most transparent to long wave radiation; often the inside air temperature of a PE house can be lower than the outside due to long wave radiation loss on clam, clear winter nights. the few degrees' difference between a PVC and a PE house is critical if the house is not heated and the temperature is around the freezing point. now that IR-resistant PE and EVA have been developed, the difference can be minimized.the characteristics of long wave transmissivity
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