The present invention relates to a device 1 formed of an envelope 2, 5 flexible carried by a bearing structure 3, 4, forming an internal volume, which can be used to cover or shield, as well as its method of manufacture. The invention finds an application to the field of greenhouses, such as the greenhouses tunnel. The flexible envelope comprises a film 2 made of plastic material assembled with an element 5 of the type of thread, so that this element 5 is disposed in the vicinity of the top of the device. The element 5 is a knitted fabric, plastic assembled by bonding with the film 2 along at least one line of heat-sealing at the level of an opening 9 in the film 2, so that the envelope is sealed over the whole of its portion comprising the film 2 and delimited by the line of heat-sealing, and that the envelope, lets the air and water and evacuates the heat on its portion comprising the opening 9 in the film 2.
