"Occupancy" can be a confusing term for building owners because when it comes to fire protection, it is used in different ways. First, there are occupancy classifications for the design, installation, and water supply requirements for sprinkler systems. These are explained in NFPA13 Standard for the Installation of Sprinkler Systems. And then, there are occupancy loads as calculated per the National Fire Protection Association (NFPA) 1 Fire Code and NFPA 101 Life Safety Code.
While both sets of requirements are intended to protect people in the event of a fire, they represent two very different ways of looking at the term "occupancy." The occupancy classifications in NFPA13 guide the construction of safer buildings by ensuring the sprinkler systems installed are appropriate for the potential hazards they contain. Thus, they are defined in terms of hazard classifications.
In contrast, NFPA 1 defines occupancy based on the intended use of a building as opposed to the hazards it might contain (i.e., its hazard classification). As a result, there are 31 different occupancy types defined in NFPA 1, all with their own specific requirements and occupant load factors, which you can find in NFPA 101 Table 18.104.22.168.
With Regard to Life Safety, "Occupancy" is All About Egress
Once the building is constructed with the appropriate fire sprinkler system for its intended occupancy, other than conducting the required inspections and maintenance for their sprinkler systems, building owners rarely need to think about occupancy in this context in their day-to-day operations.
In contrast, building owners do have to think about -- and comply with -- the occupancy load requirements determined in accordance and for the purposes of NFPA1 and NFPA 101. "Occupancy," in this sense, is all about egress -- getting people out of a building safely in an emergency.
How Occupancy Load and Maximum Occupancy is Calculated
The occupancy load of a building is the total number of people allowed in a room or space within a building and is calculated based on the intended use of that space.
Some rooms or spaces within a building may have multiple uses, resulting in different occupant loads. For example, if a room is arranged with tables and chairs, more space will be required to allow sufficient egress around the tables, reducing the number of people that can safely exit the room in an emergency. However, the same room arranged with rows of chairs would allow for more people because it would provide sufficient egress between the rows. In cases where a room or space has multiple uses, the lowest calculated occupancy always takes precedence.
You can calculate the occupancy load of a room or area using the NFPA's handy factsheet for calculating occupant loads. However, the occupancy load that you will be expected to comply with will be determined by the Authority Having Jurisdiction (AHJ). Here is the basic calculation:
Occupancy Load = Open floor space of the room (ft2) ÷ Occupant Load Factor (ft2/person)
Where: The Occupant Load Factor is based on occupancy type per NFPA 101, Table 22.214.171.124.
As a building owner, you are responsible for ensuring those exits are never blocked and that people can find them easily. Thus, providing safe egress means also having the proper signage at every egress point is critical to getting people out safely in the event of a fire -- confusion can cost lives.
NFPA 101 provides specific requirements for egress signs as well as signs indicating the maximum occupant load:
- Exit signs are needed to identify exits and direct the ways to get to those exits. This includes the location of such signs and how to illuminate them.
- Signs indicating the maximum occupancy must be posted in every room within a building. In rooms with multiple uses with multiple maximum occupancies, signs must indicate both limits. Occupancy signs must be present in the proper location, usually a conspicuous place near the main exit, and must be undamaged and legible.
Consequences for Noncompliance
Occupancy load requirements play an important role in fire safety because they help ensure that people can safely get out of the building if a fire breaks out. Remember, it's all about egress, and when it comes to compliance, blocked exits and improper or missing signage are two of the most common fire code violations. While these types of violations are easily avoidable, the maximum occupancy limits within your building require constant vigilance.
During an inspection, the fire marshal will always check to ensure that the number of people in different areas of your building does not exceed the occupancy load given its arrangement or the maximum occupancy for that space. And, if you are not in compliance, you could receive a citation as this is considered a very serious violation.
Another important thing to note is that if the use of your building changes and/or any remodeling changes the number of exits and/or the size of a given space, both the occupancy load and the maximum occupancy limits must be recalculated and approved by the AHJ.
Monitoring the number of occupants in the different spaces to ensure compliance with occupancy load requirements is an ongoing responsibility and ultimately falls to the building owner. Koorsen's goal with this post was to provide a better understanding of these requirements to help you keep your building and its occupants safe. We invite you to contact Koorsen today with any additional questions you might have about occupancy loads and what they mean for fire safety.