This paper reports insights about energy savings in buildings dedicated to tertiary activity. The goal is to employ as much as possible natural light flows to minimize the artificial light source consumption. Although the solar energy is power-efficient to light and heat a room, this natural source remains complex to manage and can generate inconveniences related to occupants visual comfort. The authors propose a global solution to deal with visual comfort by controlling the daylight contribution to the indoor light atmosphere. This control structure is based on the use of an innovative sensor of light conditions and it was implemented within an experimental room equipped with classic Venetian blinds. This paper focuses on the control laws to apply in order to meet visual needs for current tasks performed in offices.