ft’) of space per floor. A typical floor plan is shown in Figure 1. It is occupied primarily as
office space for a number of Federal agencies. A day care center is located on the first floor, a
cafeteria is located on the second floor, and a credit union is located on the fifth floor. Computer
rooms are located on floors 2, 4, 6, 7, and 9. The sub-basement and basement levels are
occupied by a parking garage and mechanical equipment rooms.

The building is a fire resistive structure with limestone exterior walls, reinforced concrete floors,
and a reinforced concrete roof. Interior partitions are mainly gypsum board or concrete block
with some hollow tile walls. The interior finish is primarily painted plaster and gypsum board.

Egress from all floors is accomplished through six stairwells. Each stair is enclosed by a shaft
of masonry construction with openings protected by 1 % hour fire rated doors. All of the stairs
discharge within unprotected corridors and lobbies on the first floor. The second floor also
serves as a level of exit discharge via a sprinkler protected skywalk leading to another building.

The sub-basement paint shop, most of the basement, first floor storage area, the day care center,
skywalk, second floor south wing, and computer rooms on the sixth and seventh floors are
protected by wet pipe sprinkler systems. These systems are reportedly designed by pipe schedule
for ordinary hazard occupancies. The sprinklers are fed by a six inch combination
sprinkler/standpipe riser located in each stair. Each riser is equipped with 63.5 mm (2 4 in) hose
valves located in the stair at each floor level. The system pressure is boosted upon demand by
a fire pump rated for 3,785 Ipm (1000 gpm) at 690 kPa (100 psi).

The building is equipped with a fire alarm system designed to provide selective evacuation.

Occupants on the appropriate floors are notified of alarm conditions by taped voice messages
over speakers located throughout the building. The speakers can also be used for live voice
communication during emergencies. Occupants of the fire floor are instructed to relocate one
floor below. Occupants of the floor above the fire are instructed to relocate two floors down.
Occupants of the floor below the fire floor are warned of the fire emergency and are instructed
to expect the occupants of the two floors above. Alarms are initiated by manual pull stations
located at each exit and stair door, sprinkler flow switches, duct smoke detectors, and computer
room smoke detectors. Each floor is equipped with telephones for use by floor fire wardens
or the fire department. Fire alarm signals are transmitted to a central station receiving service.

The building has 13 elevators, 12 passenger and one freight. Smoke detectors located in the
elevator lobbies as well as activation of any fire alarm device except for first floor devices
initiate automatic recall of the elevators to the first floor. Activation of first floor devices recalls
elevators to the second floor. All elevators have fireman’s capture and contain emergency
telephones.

Evaluation of the existence of an equivalent level of safety was one objective for the analysis
identified by the building owner (GSA). According to the equivalent level of safety regulation
(2], an analysis must indicate that the existing and/or proposed safety systems in the building
provide a period of time equal to or greater than the amount of time available for escape in a
similar building complying with the requirements of the Federal Fire Safety Act of 1992. In
conducting an analysis, the capability, adequacy, and reliability of all building systems impacting

432



The National Institute of Standards and Technology and GSA continue to work together to
expand the science of fire protection. Optimal utilization of sprinklers is a key component in
most fire protection strategies. Efforts are underway to further evaluate sprinkler response and
improve their application.

In order to use most fire models like FPETool, heat release rate data must be available. A
catalog of heat release rates for typical office furnishings is being developed. In addition to the
data required by the models, this catalog will include video footage of the fire tests and still
pictures of the tested items. Finally, validation of the FPETool fire model and its
subcomponents is an on-going effort.

CONCLUSION

Significant advances in the scientific understanding of fire have occurred over the last several
years. These advances have resulted in the development of a number of engineering tools for
measuring building fire performance. However, the application of these tools remains limited
because there is no widely accepted framework in which to apply these tools. Building and fire
codes simply state that equivalency based on performance is possible without giving any
guidance on how it is to be judged.

Currently, work is underway to develop a framework in which to utilize performance-based
equivalency. The results of this effort will foster the application and acceptance of fire
protection engineering analysis tools. By designing to meet the expected fire challenge and not
the specific code book requirements, appropriate levels of fire safety can be provided in
buildings while increasing flexibility and potentially reducing costs.

REFERENCES

1. “Fire Administration Authorization Act of 1992,” Public Law 102-522, October 26,
1992.

2. “41 CFR Subpart 101-6.6 Fire Protection (Firesafety) Engineering,” Federal Register,
Vol 59, No. 210, November 1, 1994, pp. 54524-54532.

3. Nelson, H. E., “The Application of Systems Analysis to Building Firesafety Design,”
Canadian Structural Engineering Conference, 1974.

4, “Alternative Approaches to Life Safety,” National Fire Protection Association Standard
101A, National Fire Protection Association, Quincy, MA.
5. Nelson, H. E., “FPETool: Fire Protection Engineering Tools for Hazard Estimation,”

NISTIR 4380, National Institute of Standards and Technology, October 1990.

6. Nelson, H. E., “FPETool Users Guide,” NISTIR 4439, National Institute of Standards
and Technology, October 1990.

7. Cote, A.E., “Automatic Sprinkler Systems,” Fire Protection Handbook, 18" edition,
National Fire Protection Association, Quincy, MA, February 1997, p. 6-138.

8. NFPA 1 01°, Life Safety Code®, 1997 edition, National Fire Protection Association,
1997.

437


“life safety system”, this concept is not included in the FSES. Any unsprinklered high rise
building will fail the existing version of the FSES. Since GSA typically requires an FSES for
each building fire safety analysis, it is included here primarily for completeness. At some point
in the future, the FSES may be updated to allow for the evaluation of unsprinklered or partially
sprinklered high rise buildings.

Fire modeling is another useful tool for determining equivalent level of safety. A fire model
called FASTLite [9], developed by the Building and Fire Research Laboratory at the National
Institute of Standards and Technology, was used to estimate the rate of development of
hazardous conditions within the building for certain fire scenarios. This model is the successor
to FPETool. In order to use fire modeling, the expected fire growth rate must be identified and
provided as input data for the model. Research conducted by NIST for GSA indicates typical
office building fuel packages produce heat release rate time histories which grow at a medium
rate proportionally with time-squared.

gq = at?

Specifically, three-sided office work stations were shown to produce heat release rate curves
approximating a medium growth rate, a = 0.0117 kJ/s> (Figure 2). This so-called medium
growth rate fire has been documented and used in NFPA 72, National Fire Alarm Code [10], for
establishing heat and smoke detector placement requirements. A medium growth rate fire was
used in the analysis discussed here.

Using the medium growth rate fire, several fire scenarios were identified based on a site visit and
review of the previous fire safety reports. Fires were assumed to occur in either a typical office
(7.6 m x 6.1 m x 3 m) or an open plan area (30.5 m x 15 mx 3 m). Calculations were performed
assuming the door to the fire room was either open or closed. The fires were allowed to grow
until the space reached flashover or the fire became oxygen starved. The fire could become
oxygen starved from either the ventilation limitations of the space or immersion in the oxygen
depleted upper layer. The heat release rate followed the medium growth rate fire curve for at
least the first seven minutes of each simulation regardless of room size. Using the fire model,
the impact of the fire on an attached corridor and adjacent room was examined.

The times available for safe egress are summarized in Table 1. The columns labeled “office” and
“open plan” present calculation results for fires occurring in the office space or the open plan
space, respectively. On average, the calculations indicate that without sprinkler protection a fire
will produce untenable conditions or otherwise begin to compromise the egress system in about
five minutes after the start of open flaming.

As a point of reference, the NFPA Fire Protection Handbook lists survivable condition criteria
if a sprinkler is to provide life safety [11]. Gas temperatures at eye level (1.6 m (5.25 ft) above
the floor) cannot exceed 93 °C (200 °F). The maximum allowable ceiling temperature is 260 °C
(500 °F). Finally, carbon monoxide concentration cannot exceed 0.15% by volume. The
assessment of other potentially toxic effects, such as from heat flux or toxic gas interactions, was
not addressed in this analysis. As can be seen in Table 1, standard response sprinklers do very

434


fire growth, occupant knowledge of the fire, and time required to reach a safe area must be
examined. In particular, the impact of sprinklers on the development of hazardous conditions
in the area of interest must be assessed.

Typically, so-called “standard sprinklers” would be used in office type occupancies. This type
of sprinkler would not necessarily provide the level of life safety required in the Act [7]. The
use of quick response sprinklers would be required to achieve the appropriate level of safety.
Therefore, the baseline analysis must be related to a building equipped with quick response
sprinklers and standard response sprinklers.

Three options for establishing an equivalent level of safety are provided in the regulations. In
the first option, the margin of safety provided by various alternatives is compared to that
obtained for a code complying building with complete sprinkler protection. A second alternative
is applicable for typical office and residential scenarios. In these situations, complete sprinkler
protection can be expected to prevent flashover in the room of fire origin, limit fire size to no
more than 1 megawatt (950 Btu/sec), and prevent flames from leaving the room of origin. As
a third option, any other technical analysis procedures could be used to show equivalency subject
to appropriate approvals.

The margin of safety is the difference between the available safe egress time (ASET) and the
required safe egress time (RSET). Available safe egress time is the time available for evacuation
of occupants to an area of safety prior to the onset of untenable conditions in occupied areas or
the egress pathways. The required safe egress time is the time required by occupants to move
from their positions at the start of the fire to areas of safety. Available safe egress times would
be developed based on an analysis of a number of assumed reasonable worst case fire scenarios
including assessment of a code complying, fully sprinklered building. Additional analyses
would be used to determine the expected required safe egress times for the various scenarios.
If the margin of safety including an appropriate safety factor is greater for an alternative than
for the fully sprinklered building, then the alternative should provide an equivalent level of

safety.
Margin of Safety = ASET - RSET
ASET = Safety Factor x RSET

ASET = ASET sine

alternative
A number of engineering tools are available for developing information to support an equivalent
level of safety analysis. The first tool used in this analysis is the fire safety evaluation system
(FSES) which is documented in Chapter 7 of National Fire Protection Association (NFPA)
101A, Guide on Alternative Approaches to Life Safety [4]. The FSES indicates that the building
does not provide a level of safety equivalent to the current requirements for existing business
occupancies (Chapter 27) contained in NFPA 101°, Life Safety Code® [8]. The development of
the FSES has lead to the inclusion of some inconsistencies in the document. While the Life
Safety Code® provides an option for existing high rise office buildings to be protected using a

433



a factor of safety, it is recommended that the egress times calculated in this analysis be doubled
[12]. The egress calculations assume the occupants are readily mobile and will begin leaving
the building immediately upon notification. A factor of safety more than double could be
appropriate for addressing issues such as delayed notification, limited mobility, and other factors.

In this analysis, the available and required safe egress times are almost equal for an
unsprinklered building. Typical engineering practice requires that some margin of safety be
included to address reliability and variability. One factor of safety was included in the egress
analysis where evacuation time was calculated assuming one-third of the exits were blocked.
However, additional safety factors should be included in the final assessment to address various
uncertainties. Safety factors can be applied in the form of an increase or decrease in the design
fire size, an increase or decrease in the fire growth rate, a conservative estimate for a
performance criterion, or an increase in the estimated travel time used in egress calculations [13].
The application of additional safety factors would decrease available safe egress time and
increase required safe egress time. Therefore, it can be concluded that the building as it currently
exists does NOT provide the equivalent level of safety described in Public Law 102-522 or 41
CFR 101-6.6.

In a building with complete sprinkler protection, the sprinklers would probably activate to
control the fire and limit development of hazardous conditions. In the specific case of the Peck
building, the calculations indicate standard response sprinklers would be of little or no benefit
to people located on the floor of fire. However, the standard sprinklers would provide protection
for people not located on the floor of origin. This is one reason why selective evacuation is used
in fully sprinkler protected high rise buildings. It is also evident from the calculations that the
use of quick response sprinklers would greatly enhance the protection of occupants on the floor
of fire origin as well as the other floors in the building. In addition to enhancing life safety, the
use of quick response sprinklers would limit property damage and help minimize downtime if
a fire occurs.

Department of Justice Main Building

The Department of Justice Main Building is the other building selected for analysis. This seven
story office building, located in Washington, DC, was built during the 1930s. This building is
listed on the National Register of Historic Places. It is constructed of reinforced concrete
supported by steel framing system of beams and columns. Many of the stairs are open on one
or more sides exposing them to elevator lobbies and the remainder of the building. Some
portions of the building are currently protected by automatic sprinkler systems. Many of the
offices contain substantial amounts of wood paneling and trim. As expected in this type of
occupancy, security issues are a significant concern and must be balanced against fire safety.
The analysis of this building is continuing and will not be presented in this paper.

INNOVATION INCREASES SAFETY
Through the use of the Fire Risk Assessment Methodology and FPETool, GSA is implementing

a performance-based system of building design and assessment. This methodology enables GSA
to rapidly apply the knowledge gained from its research activities in practical applications.

436



USING PERFORMANCE-BASED DESIGN TECHNIQUES TO
EVALUATE FIRE SAFETY IN TWO GOVERNMENT BUILDINGS

by

David W. Stroup
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899 USA

Pacific Rim Conference and 2nd International Conference on Performance-Based Codes
and Fire Safety Design Methods, May 3-9, 1998, Maui, Hawaii. Proceedings. Sponsored
by American Institute of Architects, Building Officials and Code Administrators
International, International Code Council, International Conference of Building Officials,
Interantional Council for Building Research Studies and Documentation, National
Research Council, Canada, Society of Fire Protection Engineers, Southern Building Code
Congress and World Organization of Building Officials. 1998.

NOTES: This paper is a contribution of the National Institute of Standards and
Technology and is not subjected to copyright.


Heat Ratease Rate (kW)

$000

4500

4000

3500

3

2500

8

1500

95 OF ENGINEERS:

unratst

Three-sided
Workstation

100

300 400 500 600
Time (5)

Figure 2. Comparison of "t-squared" and Workstation Heat Release Rates

439



Portier, R. W., Peacock, R. D., and Reneke, P. A., FASTLite: Engineering Tools for
Estimating Fire Growth and Smoke Transport, NIST SP 899, National Institute of
Standards and Technology, Gaithersburg, MD 20899, 1996.

NFPA 72, National Fire Alarm Code, 1996 edition, National Fire Protection
Association, 1996.

Cote, A.E., “Fast Response Sprinkler Technology,” Fire Protection Handbook, 17"
edition, National Fire Protection Association, Quincy, MA, July 1991, p. 5-189.
DiNenno, P.J., ed., “Movement of People,” The SFPE Handbook of Fire Protection
Engineering, 2TM edition, National Fire Protection Association, Quincy, MA, June
1995, p. 3-282.

Custer, R.L.P. and Meacham, B.J., Introduction to Performance-Based Fire Safety,
Society of Fire Protection Engineers and National Fire Protection Association,
Quincy, MA, June 1997.

438



little to improve the situation because of their relatively long activation time. The best
improvement is obtained using quick response sprinklers (RTI 40 (m-s)'”). The use of quick
response sprinklers prevents development of hazardous conditions in all of the modeled cases.

Table 1. Times in Seconds for Sprinkler Activation and Untenability

Sprinkler Time to Untenability (s)
Type Activation Time (s) Office Open Plan | Corridor

Office Open Plan Office Open Plan
None 4 x 180 300 360 400
Standard 260 425 180 300 CJ 400
Quick 171 299 ~ roa) ro} roa)
Response

The second step in conducting the equivalent level of safety analysis is determining the time
required to move building occupants from the vicinity of the fire to an area of safety. Several
models which use hydraulic flow approximations are available for estimating egress time. The
FASTLite suite of programs includes an egress model. This model was used to examine the
required egress time. Results of the egress time calculations are shown in Table 2.

Several variables were evaluated including number of occupants and number of available egress
paths. An occupant load per floor of 650 people is obtained using the occupant load factor
specified in the Life Safety Code®. Each floor is expected to hold approximately 300 people
using the GSA specified occupant load for the building. Examination of a typical floor layout
(Figure 1) suggests the possibility that a single fire could block at least two of the six exits.
Therefore, calculations were performed assuming the availability of six exits and four exits.
Depending on the assumption, the results indicate two to five minutes would be required for all
people on the fire floor to move to an area of safety. For this analysis, the area of safety was
assumed to be the floor below the fire. Additional calculations indicate that it would require an
additional 60 seconds for people to evacuate from the floor above the fire (move down two
floors).

Table 2. Summary of Calculated Egress Times in Seconds

Number of Exits | Number of | Time to Clear Floor | Time to Move
Available Occupants One Floor
6 300 70 90
650 150 200
4 300 100 140
650 220 290

Typically, the selective evacuation system used in this building is not considered appropriate for
an unsprinklered building. Therefore, it is possible that areas within the building would not
remain “safe areas” during the course of a fire. Additional calculations indicate that it would
require approximately four minutes for people on the tenth floor to move to ground level. As

435



continuity). To ensure adequate levels of safety, the relationship between expenditures on fire
safety and the actual impact of these expenditures is examined through technical analysis. Each
building in the GSA inventory is subjected to a fire safety analysis every five years. These
building surveys are conducted by fire protection engineering professionals.

A critical step in the evaluation of a building’s fire safety performance is identification of a set
of design fires. These fires are ones that could produce severe affects on the building and its
occupants. Full scale testing of fuel packages, analysis of fire loss statistics, and professional
judgment are used to establish the set of design fires. Using the design fires and building
characteristics, potential fire scenarios are modeled to determine the effects on life safety,
property, and mission. Based on this professional analysis, actual risk conditions in each
building are identified and corrective actions recommended. As necessary, building owners
allocate resources to abate significant risks.

RESEARCH ACTIVITIES

In support of its risk management philosophy, GSA has sought to look beyond the codes and
standards for methods that would allow technical assessment of building fire safety risks and
development of necessary solutions. GSA professional staff have been involved in the
development of various alternative methods of analyzing life safety such as system concepts [3]
and National Fire Protection Association Standard 101A, Alternative Approaches to Life Safety

(4).

In addition, significant resources have been devoted to the development of life safety alternatives
through scientific research. GSA has focused its research activities in three major areas: model
development and verification, suppression system effectiveness, and protection of mobility
impaired persons. The development of FPETool [5, 6] was a significant result of these research
activities. Using this package of analytical engineering tools, the development and impact of fire
in a building can be assessed. GSA has integrated the use of FPETool into its design review and
facility assessment processes for evaluation of fire risk in GSA controlled space and appropriate
resource allocation.

APPLICATION

As part of the NIST effort to continue development of the Fire Safety Assessment Methodology,
two buildings were selected for application of the performance-based design techniques. The
buildings represent a cross section of the GSA inventory. Each building contains a mixture of
occupancy groups including business, assembly, and storage. Both buildings are highrises
according to U.S building codes and are being considered for renovation in the next 5 to 10
years. Results from these fire safety assessments will be used to plan the renovations.

John W. Peck Federal Building
The first building selected for analysis was the John W. Peck Federal Building, located in

Cincinnati, Ohio. This building, constructed in 1963, has ten floors above grade, a basement,
and a sub-basement. The building provides approximately 6,178 gross square meters (66,500

431


In partial recognition of this, most building and fire safety codes contain equivalency clauses.
These clauses permit the use of alternative methods and materials when their equivalency can
be proven to the authority having jurisdiction. In the past, subjective judgement formed the
basis for determining equivalency. Continuing research into fire phenomena has made it
possible to perform an engineering analysis of the fire safety performance of a building. This
building could differ widely from current perceptions of a code conforming building. Using
analytical engineering tools, the development and impact of fire in a building can be assessed.
Recommended improvements can be prioritized based on their predicted impact on the risks
associated with potential fire exposure.

The United States Congress included an equivalency option in the Federal Fire Safety Act. This
Act, passed by Congress and signed by President George Bush in 1992, is part of the Fire
Administration Authorization Act (Public Law 102-522) [1]. The Federal Fire Safety Act
requires sprinklers or an equivalent level of safety in all new six story or higher Federal
Employee Office Buildings, and requires upgrades during renovations of such buildings if they
are six stories or higher and the renovation is more than 50 percent of the value of the structure.
In addition, when the Government leases 3,250 total aggregate square meters or more of space
and any portion is on or above the sixth floor, the entire building must be protected with

~ sprinklers or an equivalent level of safety. A “Federal Employee Office Building” is defined as
any building, owned or leased by the Federal Government, that can be expected to house at least
25 Federal employees during the course of their employment.

The General Services Administration was required by the Act to issue regulations further
defining the term equivalent level of safety. In developing the regulations, GSA held meetings
with a working group composed of representatives from the United States Fire Administration,
the National Institute of Standards and Technology, and the Department of Defense as well as
a number of other affected federal agencies, trade associations, state fire marshals, fire chiefs,
consulting engineering firms, building owners, academia, and research institutions. The final
regulation was established in the form of a performance requirement [2]. A fire protection
engineering analysis is used to measure hazard and the amount of protection provided by the
building. The concept for the final rule was derived from GSA fire protection program
philosophy and built upon the equivalency concept contained in building and fire safety codes.

RISK MANAGEMENT

Typically, government agencies in the United States do not have insurance like private sector
building owners or occupants. Any loss that occurs must be paid out of an agency’s operating
budget. A single loss could severely impact an agency’s ability to conduct nationwide
operations. Building and fire codes are intended to protect against loss of life and limit fire
impact on the community. These codes do not necessarily protect the assets of the building
owner or occupant. Simple code compliance does not ensure a level of safety acceptable to the
building owner or occupant. The continual search for code compliance is not sufficient
justification for resource allocation.

With cost effectiveness in mind, the GSA fire protection program addresses all aspects of fire
safety important to a building owner or occupant (life safety, property protection, and mission

430


Using Performance-Based Design Techniques to
Evaluate Fire Safety in Two Government Buildings

David W. Stroup, P.E.
National Institute of Standards and Technology
Building and Fire Research Laboratory
Gaithersburg, MD 20899

INTRODUCTION

The General Services Administration (GSA) is the business agent for the United States
Government. It is responsible for the acquisition and management of everything from pencils
to buildings. Within GSA, the Public Buildings Service (PBS) operates as the federal
government's real property manager. In this capacity, PBS is responsible for the acquisition,
design, construction, and operation and management of various types of space for federal
agencies.

Currently, the inventory of space includes 1700 Government owned buildings and 5100 leased
locations representing approximately 28 million square meters of space. A number of historic
buildings are included in the multitude of buildings controlled by GSA. GSA real estate leasing
policy gives preferential treatment to historic buildings. A recent survey of buildings indicated
that the oldest building in the inventory was 180 years old.

GSA is responsible for ensuring the fire and life safety of the employees and visitors occupying
the space under its control. In addition, GSA must protect federal real and personal property
assets, assure continuity in the mission of occupant agencies, and provide safeguards for
emergency forces if an incident occurs. Within PBS, the Office of Property Management
develops the methodologies and procedures used for evaluating the safety of government
occupied buildings and coordinating implementation by the GSA regional offices throughout the
nation.

EQUIVALENCY CONCEPTS

Traditionally, the design of building fire safety in the United States has relied on building or fire
safety code compliance. Conformance of individual building elements to specific code
requirements is assumed to yield an adequate level of safety. While prescriptive-based codes are
easier to enforce, design flexibility and innovation are severely limited. Typically, new code
requirements are added after a disaster to prevent recurrence. Since only individual components
of the total building fire safety system are addressed, the entire system never is evaluated to
determine the need for previously instituted code requirements. This means that building fire
protection features require an ever increasing portion of the construction budget with possibly
little or no increase in safety.

429