A leading cause of death in fires is not direct exposure to heat or flames but rather inhaling smoke (Peçanha Antonio et al., 2013). Smoke can quickly spread throughout a building via stairs, elevators, mechanical shafts, and other openings, creating devastating outcomes for occupants who become trapped and quickly overcome by the smoke. For example, during the 1980 MGM Grand fire in Las Vegas, 85 people died, 64 of whom were on upper floors far from the fire because smoke traveled through the hotel’s ventilation system and elevator shafts. 

Due to such historic fires, fire and building codes have continually evolved to integrate improvements that protect lives during a fire event. This evolution includes incorporating smoke control systems. These systems manage and control smoke during a fire, exhausting and limiting its spread within a building. Smoke control systems offer occupants a critical period to escape before building conditions become untenable.  

This article will explore the basics of smoke control, including: 

• Code requirements for smoke control systems, including jurisdictional requirements 

• Performance criteria for each building’s specific needs 

• Smoke control design guidelines and rational analysis  

Code Requirements for Smoke Control Systems

Understanding the codes being enforced in the local jurisdiction is vital for any project. Conducting due diligence is one of the most critical aspects of designing any life safety system. The due diligence phase of a project involves determining which codes are relevant and whether any amendments, modifications, or local ordinances supersede the standards typically enforced by the NFPA or ICC suite of codes. 

For example, in the State of Georgia, the Department of Community Affairs (DCA) prescribes the construction codes that are enforced, including:  

• International Building Code, 2018 Edition, with Georgia Amendments (IBC). 
• International Residential Code, 2018 Edition, with Georgia Amendments (IRC). 
• International Fire Code, 2018 Edition (IFC). 

In addition, Chapter 120-3-3, enforced by the Georgia Safety Fire Commissioner, is entitled “Rules and Regulations for the State Minimum Fire Safety Standards.” This chapter modifies the International Fire Code (IFC) and National Fire Protection Association (NFPA) codes. The DCA also amends specific chapters of the International Fire Code. It is essential to fully understand which codes are adopted and whether certain chapters are removed, modified, or amended, which is why having a fire protection consultant on a project is critical. Once the consultant completes the due diligence and identifies the correct codes, they can obtain the building requirements. 

Jurisdictional Requirements for Smoke Control Systems

For any project, it is crucial to have a knowledgeable engineer who knows the building codes enforced in the area. Building and fire codes can vary, including local amendments that change standard requirements. Buildings range in design, use, size, and classification, influencing the life safety requirements engineers must implement.  

These variations are particularly true for smoke control systems, as codes and local requirements do not require stair pressurization systems in all buildings. Understanding and researching the local jurisdictional requirements is fundamental to understanding what is being enforced in each geographical area. 

The smoke control engineer must consider the following items as part of their research of local requirements:  

What is the highest occupied floor? 
Buildings with an occupied floor over 75’ above the lowest fire service access level are considered high-rise buildings under specific applicable codes.  

What is the occupancy classification? 
The occupancy classification could result in smokeproof enclosures being required or not. 

How tall are the staircases? 
If there are staircases serving levels greater than 75’, the stairs may require smokeproof enclosures. 

How are the staircases configured? 
Smokeproof enclosures may not be required in some instances. Features of a high-rise that inform the decision to include smokeproof enclosures are whether the stairs are open-sided, the stairs serving occupied levels are less than 75’, and other criteria.  

Performance Criteria 

Performance criteria define the standards that smokeproof enclosures must be designed and operated to meet. These criteria inform key stakeholders about the system’s design, detailing the specific requirements incorporated and the performance benchmarks the system intends to achieve.  

Once it is determined that smokeproof enclosures are required and the design team selects stair pressurization as the compliance method, the applicable code will provide the necessary performance specifications. These specifications may vary depending on the jurisdiction, so a thorough review of the applicable code is essential.   

Stair pressurization systems help clear escape routes by pushing air into stairwells, preventing smoke from entering. This creates a safer path for people to exit the building. 

Common performance criteria include: 

• Positive pressure injected into the stair with the purpose of reducing smoke ingress.
• Positive pressure injected into the stair which is not restricting occupants from opening any stair access doors. 

Understanding these performance requirements is important as each building may have different needs and require specific performance specifications. 

Smoke Control Design 

NFPA 92: Standard for Smoke Control Systems and Chapter 909 (IFC and IBC) provides guidelines for designing smoke control systems. Understanding the necessary inputs, assumptions, and grounding factors will produce the most efficient and compliant designs. Over the past 25 years, the design of smoke control systems has progressed significantly with advancements in computer hardware and software resources. Since the industry has shifted from hand calculations to computational methods, accuracy and efficiency have improved.  

Effective communication is key throughout the design phase. Engaging with the design team regarding the chosen smoke control method and the location of the ductwork, fans, and other components will assist in integrating the system. Another key stakeholder is the Authority Having Jurisdiction (AHJ); involving the AHJ early in the design process is imperative. Discussing all inputs, assumptions, and performance criteria ensures the system is designed according to local requirements, with agreed-upon input assumptions before the design phase begins. 

Rational Analysis Report 

A concise analysis of the smoke control system’s design should be documented with a rational analysis report, as required by IBC and IFC. The rational analysis will contain all information about the smoke control system, which will be used for special inspections and by building maintenance personnel responsible for maintaining and periodically testing the system. 

Chapter 909.4 details seven components that should be considered as part of the rational analysis: 

The Stack Effect 

The stack effect can significantly alter the smoke control system’s ability to control smoke within a building. This effect occurs when air is drawn up through a building’s vertical shafts, including stairs and elevator shafts, due to the difference in pressure and temperature. The rational analysis must consider the building’s internal temperatures and external temperatures experienced in the building’s vicinity. Differences between external and internal temperatures must be studied and represented within the design analysis to ensure the system can function correctly under the expected environmental conditions. 

Temperature Effect of Fire  

A fire results in buoyant hot gasses accumulating and spreading near the fire seat. The expansion, temperature, and spread of smoke must be included in the analysis to ensure the smoke control system is not adversely affected. Another consideration is automatic sprinklers—how they will affect the fire and the buoyancy of smoke. 

Wind Effect 

Wind plays a critical role in the operation of a smoke control system. The rational analysis must include the force of the wind against each of the buildings’ elevations. Wind loading considerations must include the average wind speeds experienced in the building’s location. Wind loading is complex and may be influenced by adjacent structures, terrain, and the building’s overall height. Another consideration is the placement of mechanical fans and how wind loading may reduce their operation. Discussions should take place between all key-stakeholders (mechanical engineer, architect etc.) to ensure fans are placed in sheltered positions to reduce the negative impact of wind loading on the system. 

HVAC Systems 

HVAC systems should be considered as part of the overall analysis. HVAC systems typically traverse compartments, creating passages where smoke can spread throughout the building. The mechanical engineer often integrates HVAC systems into the smoke control system so that the HVAC system will shut down upon detection of smoke. Depending on the situation, dampers may be required between smoke zones, programmed to close when they detect smoke or are exposed to heat. Conversations between all key-stakeholders (fire protection engineer, mechanical engineer, and architect) are crucial in understanding how the overall building is designed to operate under fire conditions.  

External Climate 

The smoke control system will likely have components installed both outside and inside the building. Consideration must be given to whether external climate conditions will impact the performance of those components. One example is the accumulation of ice around dampers and mechanical fans. Engineers must design components to ensure they are shielded and protected from ice and snow accumulation. 

Duration of Operation 

The primary function of a smoke control system is to protect occupants during the means of egress period. The fire protection engineer should design the system to guarantee continuous operation for 20 minutes or 1.5 times the calculated egress time—typically whichever is greater. The operation duration must be part of ongoing discussions between the fire protection engineer and the AHJ.  

Completion and Presentation 

Upon completing the rational analysis, the engineer should compare the final system design to the current architectural, mechanical, electrical, and plumbing (MEP) plans. Additionally, the design team must conduct a presentation of the final system design to ensure the system’s configuration is still acceptable and that the architectural team has not made any changes. Final verifications are crucial, as building plans often change during the rational analysis phase.  

Specific items that need to be verified include:  

• The location and size of ducts are acceptable and coordinate with the current architectural plans. 
• All internal walls, doors, windows, and material make-ups have not been altered during the rational analysis.

Essentially, the rational analysis and current plans must match one another. If discrepancies are found, alterations may be required to bring the rational analysis into alignment.  

Once the rational analysis is complete, the fire protection engineer should present a copy to the local authority for their final input. The rational analysis should then be submitted with the permit package to the building official and fire marshal for their review and final approval. 

TEC Smoke Control Systems Services 

Telgian Engineering & Consulting offers smoke control services from project inception through completion. 

Our services include:  

Pre-Design Phase 

• Discuss the owner’s project requirements 
• Discuss and research different smoke control design options that may be available to the project 

Smoke Control Design Phase 

• Research and review the building design plans and documents 
• Building, fire, and life safety code consulting 
• Develop one design brief for the rational analysis prior to completing the analysis.
• Discuss brief with all key stakeholders, including design team and authorities having jurisdiction (AHJ) 
• CONTAM, CFD, fire and smoke modeling services 
• Egress modeling 
• Development of the rational analysis 
• Conduct and coordinate meetings with the authorities having jurisdiction 
• Development and continuous review of design documents 
• Development of test and acceptance criteria 

Construction Phase 

• Site installation reviews to ensure compliance with the established basis of design 
• Permit coordination 
• Continuous coordination with Authorities Having Jurisdiction (AHJ) 
• Resolution of site liability issues 
• Special Inspection services for smoke control 

Post-Construction Phase 

• Operational training of building staff on systems 
• Coordination and verification of close-out documentation 

Conclusion 

Effective smoke control systems are critical to the safety of building occupants during a fire. Engineers and designers can create systems that effectively manage smoke by understanding the governing codes, conducting thorough research, adhering to performance criteria, and following a meticulous design process. By partnering with TEC, your smoke control systems will be designed and implemented with the highest safety standards.

Contact us today to discuss how our expertise can help protect your property and the lives of your building occupants. 

About the Author

With more than 19 years experience in fire protection and life safety consulting and design, Eddie Farrow is the Regional Practice Leader, Fire Protection Engineering for the Southeast Region at Telgian Engineering & Consulting, LL (TEC). He has managed projects around the world for numerous occupancies including healthcare, industrial and mercantile, but has had a particular focus on high-rise residential and commercial facilities throughout his career.

Farrow has a broad range of expertise and specializes in smoke control systems, from the design phase through construction, as well as the maintenance of those systems. His expertise includes code consulting, performance based design, smoke modeling (hand calculations and computer analysis – CFD – FDS) and zone modeling analysis (CONTAM). Additionally, he has extensive experience in egress analysis (hand calculations and computer analysis – Pathfinder), hazardous material analysis, special inspections (atrium and stair pressurization), due diligence and negotiating with Authorities Having Jurisdiction (AHJs). Reach him at efarrow@telgian.com