In a scenario of energetic and climatic crises, every possible action finalized to a reduction of energy consumption is needed. In this context the daylight harvesting is assuming an always growing crucial role in building design, especially in offices, where the occupational profile is almost coincident with sunny hours. In this thesis work, an attempt has been made to demonstrate the benefits of the correct implementation of daylight in building lighting, through the application of parameters and metrics imposed by the Italian standards. The work has been organized starting from a theoretical introduction ending in an application case. In the first part they have been evaluated energy implications of daylight, in terms of benefits and drawbacks.