The sensitive approach to the local climatic environment was check, from the envelope in the modern architecture, at the Ruy Barbosa library, designed by the Chilean TAU office architects. It was built early at the seventies decade with a modular solar control system in precast concrete, with checked favorably performances according to methods of dynamic evaluation of natural light measured in ASE(1000,250h), and in the illuminances range 300 lux- 3000 lux. We proposed five models. It was concluded that ASE(1000,250h) approached us to criteria related to light comfort, resulting in the horizontal model (Mh) highly recommended in the restoration of light comfort, being in the range of illuminances evaluated above 75% of the sensors of the analyzed grid. The mixed East model (Mm-o), obtained positive performances, even though the perpendicular sun on the facade in the morning gave it high interior solar access to the study room.