Savings can be determined by comparing the ammeter's data to work and cleaning schedules. Observing a building at night may reveal rooms where lights have been inadvertently left on, as may routine questioning of custodial and security personnel. Reducing energy consumption does not necessarily equal reduction in cost. A promotional video from one sensor manufacturer states that the installation of occupancy sensors on a 10-kilowatt lighting circuit in a major New York City building reduced lighting energy consumption by 56 percent. Determine what kind of sensor you need.
Ultrasonic sensors can detect small motions but are often triggered falsely.
They are best used when a large area needs to be covered. They are best used in smaller spaces. Audible sensors are best applied in an industrial facility or warehouse, where machinery noise, rather than people, breaks the silence. Choose either a wall or a ceiling mount. In an open-plan office or wherever the lighting load is higher, mount the sensor in the ceiling.