Aspetti costruttivi del patrimonio serricolo nazionale

TYPOLOGICAL AND STRUCTURAL ASPECTS OF THE GREENHOUSES IN ITALY In the last years a large application of innovative technologies was observed in greenhouse cultivations. The design of a greenhouse requires skills in different fields such as the structures, the covering materials, the equipment for the microclimate control, the sensors and the environmental impact. The most diffused greenhouses in Italy are characterized generally by plastic film coverings and by very simplified conditioning equipment systems. Actually the market requires agronomic products for extended periods of the year and with a high quality, as a consequence the introduction of innovative technologies will be once more necessary. The paper deals with the constructive and equipment aspects which characterise the greenhouses, particularly greenhouse structures, covering materials and equipment are critically analysed in detail. Structural materials and shapes of the greenhouses are analysed as a function of the crops, the covering materials, the climatic conditions of the site and in relation with the standards in use. The properties of the most common covering materials, glass, rigid plastics, plastic films are described in relation with their applications. The physical and mechanical properties of the materials are discussed in relation to the agronomic requirements of the crops and to the expected lifetime of the materials. The environmental impact of the greenhouse cultivation is studied and solutions to increase its sustainability are presented: a large introduction of the soilless cultivation and the use of biodegradable plastics as covering materials. The soilless cultivation allows the reduction of the agro-chemicals, the contamination of the underground water with a higher quality of the yield. The use of the biodegradable plastics as greenhouse covering materials will improve the environmental sustainability of the greenhouse production eliminating the problem of the recycling of the plastic films produced by non-biodegradable polymeric materials.