System for shielding and controlling sun light or the light flow coming from artificial sources, especially for application to buildings, characterized in that it comprises: - a shielding system, comprising one or more side-by-side arrays of cables; - an actuation and control system for said one or more side-by-side arrays of cables, connected to a first end of said one or more side-by-side arrays of cables; - a tensioning/ balancing system for each of said one or more side-by-side arrays of cables, connected to a second end of said one or more side-by-side arrays of cables; - a supporting frame, said actuation and control system being connected to a side of said frame, said tensioning/ balancing system being connected to an opposite side of the frame; - said actuation/control system being adapted to operate as a function of the temperature and of the level of solar and light irradiation that hits it, and being adapted to keep the cables of said one or more arrays parallel therebetween in a substantially cylindrical configuration, in a position such as to generate the highest shadowing in a condition of highest temperature and irradiation, and being also adapted to determine a mutual torsion of the cables of the relevant array, until assuming a double cone configuration (hourglass), in a position such as to generate the highest lighting in a condition of lowest temperature and irradiation; - said tensioning/ balancing system being adapted to keep the cables of said one or more arrays either fixed to said frame, or in longitudinal controlled translation with respect to said frame; - said actuation/control system and said tensioning/ balancing system cooperating so as to keep tensioned said one or more arrays of cables. - a shielding system, comprising one or more side-by-side arrays of cables; - an actuation and control system for said one or more side-by-side arrays of cables, connected to a first end of said one or more side-by-side arrays of cables; - a tensioning/ balancing system for each of said one or more side-by-side arrays of cables, connected to a second end of said one or more side-by-side arrays of cables; - a supporting frame, said actuation and control system being connected to a side of said frame, said tensioning/ balancing system being connected to an opposite side of the frame; - said actuation/control system being adapted to operate as a function of the temperature and of the level of solar and light irradiation that hits it, and being adapted to keep the cables of said one or more arrays parallel therebetween in a substantially cylindrical configuration, in a position such as to generate the highest shadowing in a condition of highest temperature and irradiation, and being also adapted to determine a mutual torsion of the cables of the relevant array, until assuming a double cone configuration (hourglass), in a position such as to generate the highest lighting in a condition of lowest temperature and irradiation; - said tensioning/ balancing system being adapted to keep the cables of said one or more arrays either fixed to said frame, or in longitudinal controlled translation with respect to said frame; - said actuation/control system and said tensioning/ balancing system cooperating so as to keep tensioned said one or more arrays of cables.