If there are not presence detectors, the light should be turned off when a room is not used. This measure has to be specially considered in those spaces usually closed during weekends by assuring that any unnecessary light is switched on.
It is a free-of-charge measure that involves relevant savings (up to 20%)
This measure is narrowly related to the collaboration from the occupants or users, so providing education and training measures should be considered
The cost is zero. Signals which could be placed to educate the users, have trifling costs. It reduces electricity costs.