For spaces with variable occupancy, like restrooms, conference, rooms, storage rooms, hotel bathrooms, and lockers, consider using occupancy sensors. When doing a survey of your facility's energy use, look for places where lights are on and no one is home. If these are spaces that are empty for long periods and have short bursts of use, they could be a good fit for an occupancy sensor. There are many options for the sensors: most used in commercial settings have a sensor integrated into the switch. In guest bathrooms, you might use a sensor with an integrated LED nightlight, so that guests don't have to leave the light on in order to find their way to the restroom at night. For spaces with one owner (like a private office) it is simpler and cheaper to educate the users to turn off lights themselves.
How to document: Take pictures/video of installed occupancy sensors.