Fire protection typically consists of three primary features. Fire alarm systems are used to notify the building occupants of a fire emergency, automatic sprinkler systems are installed to suppress the fire and protect the property and buildings are constructed with fire-resistant features to allow occupants more time to escape the fire.
Protecting the public, or at least getting the public to respond, can be a challenge. Due to a relatively large volume of false alarms, the public typically ignores fire alarm signals. The usual response: If I can’t smell smoke or see flames, it must be a false alarm. Our industry must try harder to make fire alarm systems more reliable so the public will learn to respond to alarms and leave the building.
Buildings that are accessible to the public hold many challenges. Consider recent catastrophic fires with multiple deaths. Was there adequate fire protection in these cases? Was the proper type of fire protection utilized? In the case of the Station nightclub fire in Rhode Island where 100 people died, a fire alarm system was installed but not a sprinkler system. Considering the ambient sound level with a rock band playing, unless the fire alarm system were configured to stop the amplified music and turn the house lights up, it would probably be ineffective. The speed at which the fire spread was a significant factor. There was no sprinkler system because the occupant load was too low to require one. Due to this catastrophe, the codes have recently been changed to require sprinkler systems in A-2 occupancies with an occupant load of more than 100.
The Chicago office building where a fire killed six last year also had a fire alarm system. It worked. But when some of the office employees started to evacuate, they were effectively stopped by smoke in the stairwells. Unfortunately, the stairway doors were locked, so some could not get out of them.
Most public spaces are considered assembly occupancies in the codes. Others, such as shopping malls, are considered a mercantile occupancy. Public spaces can include airports, amusement parks, office buildings, houses of worship, convention centers, nightclubs, restaurants, schools and theaters. Obviously, providing adequate fire protection to ensure the safety of the occupants is the key purpose of providing this protection.
For assembly occupancies, the amount and type of fire protection required is based on occupant load. Simply put, occupant load is determined by the means of egress features. The amount of occupants allowed in a building is based on the ability to get them out in a timely manner in case of emergency. Occupant load tables are found in the Means of Egress chapters of the 2003 National Fire Protection Association (NFPA) 101, Life Safety Code (Chapter 7); 2003 NFPA 5000, Building Construction and Safety Code (Chapter 11); and the 2003 International Building Code (Chapter 10). The occupant load is determined by dividing the floor area by the occupant load factors in tables in those chapters. Depending on occupancy type, you will use either gross or net area figures. Gross floor area is the floor area inside the building with no deductions for hallways, stairs, closets, thickness of interior walls, columns or other features (from NFPA 101). Net floor area deducts those areas from the total floor area.
Most public spaces are considered assembly occupancies. The International Building Code (IBC) has five separate classifications for assembly occupancies. Chapter 3 defines an A-1 occupancy as one used for the production and viewing of the performing arts, usually with fixed seating. Examples would include movie theaters, concert halls, television or radio studios, performing arts centers or theaters. A-2 occupancies include banquet halls, nightclubs, restaurants, taverns and bars. A-3 occupancies include arcades, art galleries, bowling alleys, houses of worship, courtrooms, exhibition halls and dance halls without food or drink consumption, funeral parlors, gyms, indoor swimming pools without spectator seating, libraries, museums and waiting areas in transportation terminals such as airports or bus stations. A-4 occupancies include areas intended for viewing indoor sports such as arenas, skating rinks, swimming pools and tennis courts and A-5s are for participation in or viewing of outdoor activities: amusement park structures, bleachers, grandstands and stadiums.
Under the 2003 IBC, fire alarm systems are not required in assembly occupancies having an occupant load less than 300 people. Once the occupant load exceeds 300, a manual fire alarm system in accordance with NFPA 72 and an automatic sprinkler system in accordance with NFPA 13 are required. A sprinkler system will also be required for Group A-1 if the fire area exceeds 12,000 square feet, the fire area is located on a floor other than the level of exit discharge or if the fire area contains a multitheater complex. The size of the fire area is also a factor for Groups A-2 (5,000 square feet), A-3 (12,000 square feet) and A-4 (12,000 square feet). In Group A-5, an automatic sprinkler system is required in concession stands, retail areas, press boxes and other accessory use areas in excess of 1,000 square feet.
A fire area is defined in the IBC as “the aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or fire-resistance-rated horizontal assemblies of a building.”
Group M (mercantile) occupancies require an automatic sprinkler system if the fire area exceeds 12,000 square feet, if the fire area is located more than three stories above grade, or where the combined area of all Group M fire areas on all floors, including any mezzanines, exceeds 24,000 square feet. The IBC requires the waterflow switches and control valves of these automatic sprinkler systems to be electrically supervised by a fire alarm system connected to an approved central station, remote supervising station or proprietary supervising station in accordance with NFPA 72. The IBC allows an audible signal at a constantly attended location as an alternative to monitoring if approved by the building code official.
Assembly occupancies with an occupant load of 1,000 or more are also required to have an emergency voice/alarm communications system.
Group M occupancies other than covered malls complying with Section 402 of the IBC require a manual fire alarm system if they have an occupant load of 500 or more persons or more than 100 persons above or below the lowest level of exit discharge. When the building is occupied, the manual fire alarm system is allowed to activate an alarm signal at a constantly attended area—for example, the security office—from which evacuation instructions will be sent out over the emergency voice/alarm communication system instead of automatic activation of the alarm notification appliances.
Section 402 of the IBC contains the requirements for covered malls. An automatic sprinkler system is required throughout all occupied spaces. Unoccupied spaces can either have an automatic sprinkler system or some approved alternative protection. Sprinkler protection for the mall must be independent from the sprinkler systems in the tenant spaces or anchor stores. However, they are all allowed on the same system if it is independently controlled. Covered malls exceeding 50,000 square feet must have an emergency voice/alarm communications system.
In addition to the requirements in codes such as the IBC or Life Safety Code, and the installation, testing and inspection requirements of NFPA 72, fire alarm systems installed in public spaces are required to meet the requirements of the Americans with Disabilities Act Accessibility Guidelines (ADAAG). Primarily, this will affect mounting heights of manual fire alarm boxes and the location and mounting heights of fire alarm strobe lights. Because owners of public buildings want to make their properties pleasing to the eye, many times fire alarm devices are hidden from view. It is not uncommon to see manual pull stations hidden from view or strobe lights obstructed by plants. Fire alarm companies performing tests and inspections of these properties need to remind owners that fire alarm devices must be accessible and in plain view.
In many cases, it may be most effective to install strobe lights on ceilings, especially in the tenant spaces. Although ADAAG does not specifically permit ceiling mounting of strobe lights, they do allow “equivalent facilitation” to be used. Ceiling-mounted strobes can be much easier to see in these areas. However, remember that ceiling-mounted strobe lights must be listed for that application and installed properly in accordance with NFPA 72.
Special amusement buildings with an occupant load of more than 50 must comply with the requirements of the appropriate Group A occupancy and Section 411 of the IBC, where applicable. They are required to have both an automatic fire alarm system per Section 907 and an automatic fire sprinkler system per Section 903. An emergency voice/alarm communications system must be installed. An actuation of any one smoke detector, the automatic fire sprinkler system or other automatic fire detection devices must immediately sound an alarm in a constantly attended location in the building from which emergency action can be implemented.
Regardless of the type of public building, the requirements for fire protection are quite similar. Most public buildings will have an automatic sprinkler system, a minimum of a manual fire alarm system and duct smoke detectors connected to the fire alarm system. The occupants must be notified of an alarm but not necessarily automatically. Voice messages may be manually actuated from a constantly attended area. In addition, the building must be made accessible to meet the requirements of ADA. The requirements in the codes are relatively straightforward, so there should be few problems due to interpretation. EC