the number of units in use, such as hotel rooms, apartment flats, or offices. When a motel is at full occupancy, it is common practice to turn on a NO VACANCY neon sign. Completely vacant buildings can also attract crime. A 2017 study found that demolishing vacant buildings "reduce crime by about 8 percent on the block group in question and 5 percent on nearby block groups". Occupancy can also refer to the number of persons using an undivided space, such as a meeting room, ballroom, auditorium, or stadium. As with building codes, fire protection authorities often set a limit on the number of people that can occupy a space at one time. These limits are established primarily to allow all occupants safe passage through exits, but can also be employed to preserve the integrity of a structure. An occupancy sensor is a device that can tell if someone is in a room, and is often used in home automation and security systems. These are typically more advanced than motion sensors, which can only detect motion. Other meanings In transport engineering, occupancy can refer to: The number of passengers occupying a vehicle The percentage of time in which a detector is occupied by a vehicle The average number of particles occupying a state In football, occupancy can refer to: A team that does not currently have a manager, a president, or a home stadium See also Building code Construction Fire protection Fire-resistance rating Fireproofing Firestop List of human habitation forms Passive fire protection Penetrant References Fire protection