Fire, Life Safety

Your questions answered: Fire and life safety system design

Several questions about fire protection, life safety and NFPA codes were not addressed during the live event. Learn more in this Q&A

By Raymond A. Grill, PE, FSFPE, LEED AP October 27, 2020
Courtesy: CFE Media and Technology

During the Oct. 20, 2020, webcast on “Fire and life safety system design” several questions were left unanswered. Ray Grill replied to several questions. The webcast presenters are:

  • Raymond A. Grill, PE, FSFPE, principal, Arup, Washington, D.C.
  • Joshua D. Greene, PE, associate principal, Simpson Gumpertz & Heger, Waltham, Mass.

Question: Doesn’t critical information design system, which details the building footprint, play a role when firefighters have to fight a fire?

Ray Grill: It is important that the responding firefighters understand the building and that proper information is provided. It is also important that the responding companies pre-plan and become familiar with complex structures in their response areas so they can efficiently operate within the buildings in an emergency.

Question: Can there be a hybrid wet and dry sprinkler systems when there needs to be an area of a building that is too cold for a wet system installation?

Ray Grill: Different types of sprinkler systems can serve different areas of a building, depending on the conditions. This is done all the time. A good example is parking decks in a high-rise building. The parking decks are typically not conditioned and therefore provided with dry sprinkler systems, while conditioned areas are provided with wet sprinkler systems.

Question: Please explain the difference between NFPA 101 and the International Building Code.

Ray Grill: The International Building Code is a building code that contains comprehensive requirements addressing the entire building design, including structural and material characteristics based on construction types. NFPA 101 was originally developed with the goal of providing life safety and appropriate egress facilities in buildings. It does address minimum construction requirements for certain types of occupancies, but not all occupancies. NFPA 5000 is the NFPA version of a building code, which provides comprehensive building construction requirements. For more information, review the “Origin and Development of NFPA 101” found on the first page of the code.

Courtesy: CFE Media and Technology

Courtesy: CFE Media and Technology

Question: How do you design for voice intelligibility?

Ray Grill: This can be a complex question depending on the type of facility, or it can be an easy answer. Design for intelligibility in buildings that have reasonably good acoustical characteristics can be as simple as making sure that audibility is being met for pre alert tones. For areas with challenging acoustical characteristics, it may be appropriate to model the space as part of the design process. Programs such as EASE (enhanced acoustic simulator for engineers) can be used to inform the design for intelligibility.

Question: In a 30,000-square-foot, single story office building that is fully sprinkled, where are smoke detectors required?

Ray Grill: Unless there are special hazards or an owner requirement for smoke detection, the only smoke detectors that would typically be code required for this type of facility may be duct detectors for HVAC shutdown.

Question: What are the best practices to reduce false alarms?

Ray Grill: Good design and installation is the best way to avoid unwanted alarms. That means not putting devices in locations where they would be susceptible to unwanted alarms and using devices appropriate for the hazard. Providing more initiating devices than necessary to protect the hazard can also increase the potential for unwanted alarms.

Question: What can be done to remove end-of-life components?

Ray Grill: Most manufacturers have designed backward compatibility into their product lines. This can allow for a minimally disruptive upgrade to phase out end of life equipment.

Question: How can existing building systems be simplified without compromising safety?

Ray Grill: This is really a site-specific issue. The specific hazards in a building would need to be reviewed and the passive and active fire protection features would need to be considered.

Question: When designing fire alarm systems, is the electrical engineer responsible for the design or is it the fire alarm installer/contractor, because some engineers indicate on the drawings that the drawings just show a general layout of the devices?

Ray Grill: This is a contractual issue that can vary form one project to another. The responsibility needs to be determined early on in a project. It is very common for the electrical engineer to develop scoping documents and concepts (device types and locations, input/output matrix, initiating and notification zoning, etc.) that have to be met by the detailed design that would typically be developed by the contractor. Fire alarm design is product specific. Unless the owner determines the specific products it wants implemented, preparation of a generic detailed design is not possible.

Raymond A. Grill, PE, FSFPE, LEED AP
Author Bio: Raymond A. Grill is a principal with Arup and currently serves as the chair of NFPA 13 Technical Committee on Sprinkler System Installation Criteria. Grill is a member of the Consulting-Specifying Engineer editorial advisory board.