Smoke Control Series – Part One: History and Basic Terms

Written by Michael Ventola

Smoke Control systems, or more appropriately referred to as “Smoke Containment” or “Smoke Management” systems are relatively new design concepts for life safety in large structures. Compared to automatic detection and alarm systems that date back almost a century, smoke control codes and standards only began in the mid 1980’s and were codified in the late 1990’s. This catalyst of change was a result of countless deaths over decades and peaked in 1980 with the MGM Grand fire in Las Vegas Nevada.  Change can be slow and the cost high, eventually common sense and advanced technology prevails in devising solutions that make our community safer resulting in lives saved. 

Throughout history, there have been numerous tragic fires in buildings that resulted in significant loss of life and property damage. These events often prompted investigations and inquiries into the causes of the fires and the effectiveness of existing fire protection measures. Two high-profile incidents such as the Triangle Shirtwaist Factory fire in 1911 in NYC and the Las Vegas MGM Grand Hotel fire in 1980 highlighted the need for improved fire safety measures, code enforcement changes as well as the real beginnings of smoke control systems that we know today. 

The Triangle Shirtwaist Factory fire, which occurred on March 25, 1911, in New York City, is one of the most infamous industrial disasters in American history. Here are the details of this tragic event: 

The fire broke out on the eighth, ninth, and tenth floors of the Asch Building at the corner of Washington Place and Greene Street in Manhattan NYC. 

The cause of the fire was a discarded cigarette in a bin of fabric scraps on the eighth floor. The factory was overcrowded and housed many flammable materials, contributing to the rapid spread of the fire across the originating floor and one floor up and down. 

The fire quickly spread due to the highly combustible materials and the lack of adequate fire safety measures in the factory. The building’s exits were insufficient, locked, or blocked, and the fire escapes collapsed under the weight of fleeing workers. 

Tragically, 146 workers, mostly young immigrant women, died because of the fire. Many were unable to escape due to locked doors and blocked exits, while others jumped to their deaths from the upper floors to escape the flames. 

The local fire department responded quickly to the scene; however, their ladders could not reach the upper floors of the building to aid in evacuation and fight the fire. Firefighters were helpless as they watched workers trapped inside the burning building. 

The Triangle Shirtwaist Factory fire prompted widespread outrage and led to significant reforms in workplace safety and labor laws. It exposed the appalling working conditions faced by immigrant workers in many factories and spurred efforts to improve fire safety regulations and enforcement. 

In the aftermath of that fire, New York State established the Factory Investigating Commission, which conducted hearings and investigations into workplace safety issues. These efforts resulted in new labor laws and regulations aimed at improving workplace conditions and preventing similar tragedies in the future. 

The Triangle Shirtwaist Factory fire remains a powerful example of the need for strong workplace safety regulations and serves as a reminder of the human cost of neglecting fire safety measures. 

The MGM Grand fire, also known as the MGM Grand Hotel fire, occurred on November 21, 1980, in Las Vegas, Nevada. This was a cold morning that allowed stack effect on the building to play a role in the 85 deaths, mostly on the upper floors, to happen that morning. 

The fire took place at the MGM Grand Hotel and Casino, which was located on the Las Vegas Strip. A premier hotel at the time and was almost sold out that week before Thanksgiving. 

The fire started in the early morning hours, originating in the Deli restaurant on the ground floor of the hotel just off the casino floor. This area was previously a 24hr deli which exempted the space from having sprinkler systems installed.  Due to a renovation change, the deli was no longer operated 24/7 and was in violation of upgrade requirements requiring fully automatic sprinklers throughout the space. The fire was ignited by an electrical ground fault in a refrigerated pastry display case and went undetected for a significant period. 

Due to the lack of early detection and automatic suppression, the fire quickly spread through the casino and hotel due to highly flammable materials, such as furnishings and decorations. The building’s open design, no smoke compartmentation and lack of firestops allowed the fire to spread rapidly across multiple floors. Toxic smoke and gas were unobstructed and easily spread vertically through the building due to stack effect and open vertical chases. 

The fire claimed the lives of 85 people and injured hundreds more. Many of the victims were trapped in their hotel rooms or overcome by smoke and toxic fumes while trying to escape. 

Emergency responders, including firefighters and paramedics, rushed to the scene to battle the blaze and evacuate guests and employees from the building. However, the fire’s rapid spread and intensity posed significant challenges for rescue efforts. 

The MGM Grand fire was one of the deadliest hotel fires in U.S. history and prompted widespread concern about fire safety in high-rise buildings and hotels. It led to significant changes in fire codes and regulations, including the implementation of stricter building codes, enhanced fire suppression systems, and improved evacuation procedures. NFPA 92 A was adopted in 1988 and NFPA 92B was adopted in 1991.  Far longer than one would expect after such a tragedy. 

Following the fire, investigations revealed deficiencies in the hotel’s fire safety measures, including inadequate smoke detection and alarm systems, insufficient fireproofing, no automatic sprinkler systems where required, and a lack of emergency exits. The lessons learned from the MGM Grand fire contributed to improvements in fire safety standards and practices across the hospitality industry. 

Overall, the MGM Grand fire served as a catalyst for reform in fire safety regulations and spurred efforts to prevent similar tragedies in the future. It remains a stark reminder of the importance of robust fire prevention and suppression measures in public buildings and structures. 

Condensed Historical Timeline  

In the mid 1980s, the National Fire Protection Association (NFPA) created a Smoke Management Committee to develop a Recommended Practice that would describe how building automation systems could be used to extend the time available for people to exit a building during a fire. The document developed by this committee was published in 1988 as NFPA 92A Recommended Practice for Smoke Control Systems.  

NFPA 92A described methods that could be used to minimize the spread of smoke during a fire by using fans and dampers to create pressure differences to largely contain the smoke to the area of origin and minimize smoke spread to other parts of the building. This approach came to be known as the “pressure sandwich” approach and is also referred to as “zoned smoke control.” NFPA 92A also described a hierarchy of priorities that the building control system should use to determine what to do when confronted with conflicting inputs from the normal heating, ventilating, and air conditioning (HVAC) operation; automatically activated signals from a fire alarm system; manual inputs from building personnel; and manual inputs from the fire service.  

Also, around this same period ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) published several bulletins on HVAC controls and calculations for smoke control principals.  Over the next two decades ASHRAE continued to advance their technical and engineering documentation publishing several books on smoke control system designs and smoke management.  Finally in 2012, the premier engineering handbook on Smoke Control was published by ASHRAE. This handbook, written by John H Klote, James A Milke, Paul G Turnbull, Ahmed Hashef and Michael J Ferreira is the culmination of three decades of knowledge and validation of conceptual concepts for smoke control. 

In the late 1980s, Underwriters Laboratories Inc. began developing requirements that would be used to investigate control equipment that could implement the recommended functions described in NFPA 92A. The resulting requirements called for evaluating the equipment to the same hardware reliability standards that were used to evaluate fire alarm systems, and to evaluate operation of the equipment according to the recommendations of NFPA 92A, including implementation of the response priority hierarchy. In 1989, UL issued its first listing under the category “Smoke Control System Equipment,” with the assigned Category Control Number (CCN) of “UUKL.” “Smoke Control System Equipment” became the fifth product category whose requirements were placed under the umbrella of UL 864 Standard for Control Units and Accessories for Fire Alarm Systems. It is important to note that CCNs are specific to UL Solutions and that other nationally recognized test laboratories such as NRTL or FM may use other terminology to indicate smoke control system equipment listing.  

In 1991, NFPA published another document describing optional usage of building automation systems to extend the time available for occupants to exit a building. This document, published as NFPA 92B Guide for Smoke Management Systems in Malls, Atria, and Large Areas, focused on protecting large, non- compartmented spaces. It provided equations for calculating the amount of smoke produced from a fire, as well as guidelines for determining appropriate fan sizes to exhaust the smoke from these large areas to prevent the smoke from descending to occupied levels.  This is also known as maintaining a tenable safe environment for evacuation.  

Over the years, these documents were revised multiple times. As more systems that implemented their recommendations were installed, more was learned about what could be done to further benefit building occupants during a fire, and additional recommendations and refinements were added.  

By the early 2000s, the NFPA Smoke Management Committee felt that enough was known about the science of fire and smoke development, and what a building control system could and should do to enhance life safety for building occupants, they decided to convert NFPA 92A and NFPA 92B into standards. Both were completely rewritten in mandatory language, and any previous content that constituted recommendations beyond minimum requirements was moved to their annexes. In 2000, the revised document on smoke control systems was released as NFPA 92A Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences. In 2005, the revised document for smoke management systems was released as NFPA 92B Standard for Smoke Management Systems in Malls, Atria, and Large Spaces. With these documents now written in mandatory language, it became possible for them to be referenced by building codes.  

In 2012, to remove confusion about which document applied and to ensure there were no conflicting requirements in buildings that contained both types of systems, NFPA 92A and NFPA 92B were consolidated into a single document titled NFPA 92 Standard for Smoke Control Systems. The content of NFPA 92 is fundamentally identical to the content in the two source documents, except that all systems described in the document, regardless of the method used to modify the movement of smoke, are now called smoke control systems. Where requirements differ by objective or method used, they are called out, specifically using the terms “smoke containment systems,” “zoned smoke control systems,” or “smoke management systems” (to describe systems formerly covered by NFPA 92B).  

What started out many years ago as a couple of documents containing recommendations for how a building automation system that was already in a building might be used to provide some benefit during a fire, has now evolved to the degree that this operation is required in buildings over a certain size or containing certain types of occupancy.