The European Standard UNI EN15232 "Energy performance of buildings - Impact of adjustment and building management" highlights how the inclusion in buildings (residential and commercial) of the Control and Automation Systems implies a reduction in consumption energy in general and mainly of the most important:

The lighting is regulated by the UNI EN15193 "Energy requirements for lighting" - where you specify the methodology for calculating the energy consumption of lighting systems in interior of buildings and defines a numeric indicator of the energy requirement (LENI) for lighting to be used for energy certification.

To reduce the energy used by the plant, it can change the power absorbed from the lighting fixtures and / or the turn-on time of the lamps must prefer the configuration of the system less energy among those able to meet the pre-set lighting requirements.