Illumination device for illuminating an environment (7), including a visible source (2), which emits a visible beam, and a diffuse light generator (2, 4; 68; 150), which includes an optical structure (4; 64; 150) delimited by an inlet surface (Si; S3), which receives the visible beam, and by an outlet surface (S2). The generator emits from the outlet surface diffuse visible light and direct visible light. The illumination device further includes an infrared optical source (15), which is different from the first visible source and emits an infrared beam so as to impinge on the inlet surface; the optical structure transmits at least one portion of the infrared beam. The illumination system further includes a ventilation system (40) which can be coupled to the environment, which introduces air masses into the environment, in pulsed mode.