# Occupancy

Within the context of building construction and building codes, occupancy is the use (actual or intended) of a building (or its portion) for the shelter or support of persons, animals or property. A closely related meaning is the number of units in such a building that are rented, leased, or otherwise in use. Lack of occupancy, in this sense, is known as vacancy.

## Building codes

It is possible to have multiple occupancies (or building uses) within one building. For example, a high-rise building can have retail stores occupying the lower levels, while the upper levels are residential. Different occupancies within a building are separated by a fire barrier with a defined fire-resistance rating. It is common for a penetration (such as a fire door) to have a fire protection rating lower than the wall fire–resistance rating in which it is installed. For example, a two-hour fire separation normally requires fire doors rated at 90 minutes.
For some high challenge occupancies, the code requirements for an occupancy separation are more stringent than for other fire barriers, even with an identical fire resistance rating. In this case, an occupancy separation with a two-hour fire-resistance rating may not be able to "de-rate" its closures, such fire doors and firestops. For example, a two-hour rated "high challenge fire wall" requires two-hour rated fire doors.
Firestops in occupancy separations are also more likely to require an equal fire protection rating (a fire resistance rating for closures). They also must provide a temperature rating ensuring that the components of the firestop systems, including the penetrants are not permitted to rise in temperature above 140°C (284°F) on average or 180°C (356°F) at any single point, to lower the likelihood of auto-ignition on the unexposed side. In this manner, occupancy separations are treated similarly to fire walls which are structurally stable in case of a fire, thus limiting the danger of fire-induced building collapse.
In this sense, there are two occupancies in many single-family homes: the garage and the living space of the home. Because automobile gasoline is flammable, an occupancy separation is often required between the two should there be a vehicle fire. Water heaters and central heating are often placed in this space as well for their use of natural gas, propane, or other fossil fuels in combustion. This also helps to prevent carbon monoxide poisoning.

## Building utilization

Occupancy can also refer to 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
In combat sports such as boxing and Mixed martial arts, as well as in Pro Wrestling, the term vacant is used when a championship does not currently not have a champion, this often occurs if a current champion is unable to defend a title. This is often due to reasons such as the champion suffering an injury or illness, leaving a promotion for another, being fired from a promotion, failing to make weight for a fight, having a contract dispute, failing a post-fight drug test, being arrested, inactivity, moving up a weight class, not finding an opponent, and winning a championship in another weight class. In Pro Wrestling the title may also be vacated for kayfabe storyline reasons such as an authority figure stripping a title from a current world champion in the midst of a feud between them. In some combat sports promotions may be able to hold to hold on to a championship despite not being able to defend it for an extended period of time as an Interim champion is crowned is often faces the current world champion when they return.
In politics and human resource management, the term "vacant" is used if a position is not filled or has no current officeholder. This may often lead to the start of a succession process, a new candidate being later selected to fill the position, or an election being called to determine a new office or position holder.