April 6, 2018 - Fire Safety/Protection
By David Dawdy
While the spread of fire and flames is commonly perceived to be the biggest threat to life safety in fires in high-rise buildings, smoke and toxic gas often pose an even greater danger for occupants. High-rise structures typically include multiple stairways and internal elevator shafts. These enclosures and hoistways can act like a chimney or flue in a fire, allowing smoke to infiltrate otherwise safe floors of commercial and residential buildings. Coiling smoke doors are one option to address those life safety risks.
Despite being protected by fire-rated, car-mounted doors, hoistway shaft openings are especially dangerous, allowing hot smoke and products of combustion to infiltrate the area and potentially spreading gases throughout a multifloor building in a matter of minutes. The ability of smoke and hot gasses to migrate quickly through unobstructed vertical shafts can result in smoke inhalation and death for those trapped on seemingly untouched or "safe" floors above the fire.
To address smoke migration, the International Building Code (IBC) — beginning in 2000 — required elevator lobbies to be constructed as smoke enclosures so as to encapsulate hoistway openings on every floor of a high-rise building. Swinging doors — at the entrance to an elevator lobby — are activated during a fire event to close and seal the space, thereby minimizing smoke and gas infiltration. Elevator lobbies have made a tremendous impact on life safety but they also come with significant design and facility planning drawbacks.
The IBC eventually approved the use of coiling fabric or film closures for hoistway openings meeting Underwriters Laboratories (UL) 1784, Smoke and Draft Control Door Assemblies, requirements in 2003. Manufacturers also began to develop new alternatives to elevator lobbies at the hoistway opening, which help keep occupants safe and increase leasable/usable space in a variety of buildings.
The use of special coiling smoke doors as hoistway enclosures has quietly become mainstream in the design community. Standards from the National Fire Protection Association (NFPA) continue to evolve to include new opportunities with regard to smoke and fire infiltration in commercial buildings.
Whether discussing traditional elevator lobbies or newer products, it is important to understand these developing standards of elevator smoke enclosures and their impact on facility managers, building owners, and ultimately building occupants.
Hoistway closures are seen by the overhead door community as specialty products surrounded by a significant degree of mystery, misinformation, and misunderstanding. There are a number of reasons for this, including unfamiliarity with code standards; minimal understanding of the functional requirements of the system compared to traditional fire doors; and limited access to the training necessary to acquire this knowledge.
The first major development in this product’s acceptance came several years ago when the IBC approved the use of coiling fabric or film closures for hoistway openings. (For more information, refer Section 713, Shaft Enclosures, of the IBC.) As a result, the employment of these products — for creating additional square-footage and more spacious designs in lieu of constructing elevator lobbies — has become popular in the architecture and design community. This has led to greater visibility among facility managers, building owners, and end-users.
Elevator lobbies can decrease leasable/usable floor space for building owners and can constrain more spacious area designs. In today’s world of open concept design, elevator lobbies are often incongruent to the overall conceptual vision, according to Gregory Cahanin, fire-protection engineer and code consultant.
Newer sliding-type fire doors complying with smoke and draft requirements are frequently allowed as an alternative to building lobbies. In some applications, accordion-type doors are also employed to seal banks of hoistways. Rolling steel fire doors are specifically not allowed. However, they may be used on lobby designs that also include listed swing doors providing personal egress.
If this sounds confusing, it is. Evolving standards from the International Code Council (ICC) and NFPA mean new alternative products meeting intended performance criteria — and probably more cost-effective — may become available.
Modern elevator hoistway closures range from semitransparent film-type materials to woven, coated fiberglass materials. The intent is to seal hoistway openings to prevent smoke migration during a fire, allow for through-passage of car occupants, and to reseal the opening if opened during an alarm for access.
From the first steam-powered lifts of the industrial revolution to high-speed elevator cars, vertical transportation has made life more convenient for riders around the world. It has also evolved to meet specific needs of building owners, occupants, and first responders.
Public passenger elevators are installed to serve all floors of a building or may have separate banks targeting exclusive floors, which requires multiple lobbies to protect the hoistway from the migration of smoke and other products of combustion. These are a good target for hoistway closures since they do not require the construction of lobbies in the design.
When public elevators need to be used for emergency evacuation, hoistway smoke closures are still an appropriate use based on 2015 IBC Section 713.14.1, “Elevator, Dumbwaiter and Other Hoistways,” which states, “Enclosed elevator lobbies are not required where additional doors are provided at the hoistway opening…when tested in accordance with UL 1784 without an artificial bottom seal.”
There are some IBC codes and sections facility managers and buildings owners must be aware of, including Section 403.6.2, “Occupant Evacuation Elevators: Where installed in accordance with Section 3008, passenger elevators for general public use shall be permitted to be used for occupant self-evacuation. Where elevators are to be used for occupant self-evacuation during fires, all passenger elevators for general public use shall comply with Section 3008 (10 sections).”
Since these types of elevators are intended to be occupant-operated during evacuation periods, they must be in a hardened shaft with a one-hour fire resistance rating up to four stories and two-hour rating above four stories. Additionally, occupant evacuation elevators require lobbies at all floors except the level of discharge, meaning there is no code provision for hoistway closures.
Unlike public passenger and occupant evacuation elevators, fire service access elevators provide a capable and durable hoistway with the ability to operate for extended periods during a fire to aid fire fighters and emergency responders in assistance and rescue efforts for all occupied floors. Fire service access elevators must serve all floors.
In buildings with an occupied floor more than 36.5 meters (120 ft.) above the lowest level of fire department vehicle access, no fewer than two fire service access elevators — or all elevators, whichever is less — shall be provided in accordance with Section 3007, “Fire Service Access Elevators.” Each fire service access elevator shall also have a capacity of not less than 1587.5 kg. (3500 lb.), shall comply with Section 3002.4, and must accommodate an ambulance stretcher.
Similar to evacuation elevators, fire service access elevators must be in a hardened shaft with a one-hour fire resistance rating to four stories and two-hour rating above four stories. Typically, at least one fire service access elevator is the building service elevator and typically runs in a separate hoistway core from public or occupant evacuation elevators. In buildings with the fire service access elevator requirement, a second elevator can be designated as fire service access elevator — this may be another fire service access elevator or a public elevator.
Fire service access elevators are also required to have an elevator lobby from the second floor up as long as the floor of discharge is sprinklered. Therefore, hoistway seals are not required in 2015 IBC 709.4.2, “Smoke-barrier Walls Enclosing Areas of Refuge or Elevator Lobbies,” within fire service access elevator lobbies.
Elevator lobbies are also not required where the elevator serves open parking garages (per Section 406.5, “Open Parking Garages”). They are not required at levels of discharge as long as this level is equipped with an automatic sprinkler system and wherever the hoistways open to the exterior.
While understanding the unique needs and IBC code requirements for different types of elevators and hoistways is fundamental, there is more than one organization. The NFPA is a global nonprofit organization, established in 1896 and devoted to eliminating death, injury; and property and economic loss caused by fire, electrical, and related hazards.
Virtually every building, process, service, design, and installation is affected by NFPA’s more than 300 codes and standards, and the organization has made significant progress in smoke and fire protection with regard to elevator hoistway closures in commercial buildings.
This includes acceptance testing after installation as well as annual inspection, maintenance, and testing. New standards have been developed specifically for hoistway closures by the NFPA 80, Standard for Fire Doors and Other Opening Protectives, technical committee and will be available in their upcoming publication.
Per NFPA 80 Section 5.2.3 Acceptance Testing: acceptance testing of smoke protective curtain assemblies for hoistways must be performed by a qualified person with knowledge and understanding of the operating components of the assembly type. Before any testing occurs, a visual inspection needs to be performed to identify any damaged, field modified, or missing parts that can create a hazard during operation or resetting.
Additionally, there are a number of items requiring verification during this stage, including labels; mounting and assembly components; hoistway smoke detectors; and auxiliary hardware.
NFPA standards also require potential hoistway enclosures to have an average closing speed of no less than 152 mm. (6 in.) per second or more than 610 mm. (24 in.) per second.
NFPA mandates hoistway enclosures be installed in accordance with their listed manufacturer installation instructions. Naturally, they shall also be in accordance with American Society of Mechanical Engineers (ASME) A17.1, Standard for Elevators and Escalators.
Following installation, operational and drop testing is required in accordance with NFPA 80 Section 5.2.3, with all inspections and testing signed by a witness and kept for inspection by the authority having jurisdiction (AHJ) for the life of the assembly.
Periodic testing is mandatory. Facility managers are required to have inspection and drop testing performed annually. This testing includes all of the items noted in NFPA 80, Section 5.2.4 Periodic Inspection and Testing: comprising visual inspection, operational evaluation, drop test, and system reset (including any emergency power sources).
When specific maintenance actions are required, repairs and work are the owner or property managers’ responsibility and should be completed without delay. Only qualified professionals should make the repairs. If the unit is beyond repair or the original manufacturer’s parts are not available, the entire assembly or appurtenance must be replaced.
For nearly five decades, the fire protection industry has looked at fire and smoke spread in tall buildings and sought code-based solutions. The use of fire sprinklers to control fire spread and smoke generation in high-rise buildings has reduced both property and life loss. When sprinklers are present, smoke has become the recognized killer in high-rise fires — its upward migration from a lower floor has become a greater threat to occupants than the fire itself. Innovation in compartmentation of the vertical openings elevator shafts has evolved from the creation of lobbies to isolating the shaft at the door openings on each floor.
The changes in fire and building codes are a result of the door industry looking to help solve the fire problem in high-rise buildings by employing innovative products at elevator openings. The integration of new materials into mechanical closure systems with the ability to withstand heat exposure from a fire has progressed rapidly in the last decade. The resulting win-win for facility managers and building owners is more cost-effective choices in the use of space once reserved for elevator lobbies.
David Dawdy, director of fire and life safety new product development at CornellCookson, is a fire protection code and standards specialist. Dawdy is a member of NFPA 80, Standard for Fire Doors and Other Opening Protectives, technical committee, and Underwriters Laboratories (UL) standards technical committee. He attends International Code Council (ICC) hearings as an advocate to fire protection standards. He can be reached at David.Dawdy@cornellcookson.com.
