Install motion sensors or timers on light switches (particularly in bathrooms and storage areas)

Why

Lighting accounts for almost a third of commercial electricity use.  Lights use the least energy when they are turned off.  If your staff or clients are not in the habit of turning off lights when they leave the room, maybe it’s time to automate that for them.

How

Talk to your lighting supplier.  There are several different types of occupancy sensors to be used in different types of spaces.  Some need to “see” the person, and others use different types of sound.  You don’t want to leave your clients sitting on the john in the dark.  Also, occupancy sensors can be used to turn lights on and/or off.  Maybe you have a space where people can turn on the light as they enter, but you want it to automatically turn off when they leave.
Spaces suitable for occupancy sensors are:  washrooms, storage rooms, file rooms, hallways (some lighting can stay on, and the rest come on when someone enters the hall), entries, etc.