MS in Fire Protection Engineering
College of Engineering
Frederick Mowrer and Christopher Pascual
This report is an analysis of the fire protection capabilities of Engineering IV (Building 192) at Cal Poly University in San Luis Obispo, CA. The overall objective of this report was to assess whether the building and its fire protection systems supported the evacuation of occupants from the building in a safe manner before conditions became untenable during a fire event. The assessment was accomplished by performing a prescriptive and performance analysis.
The purpose of the prescriptive analysis was to determine whether the building egress components and fire protections systems were designed, built, and installed in compliance with all the applicable safety and building codes. The prescriptive analysis portion of this report compares each fire protection system with the requirements of the appropriate National Fire Protection Agency (NFPA) and International Building (IBC) codes. This report specifically analyzes the following areas of Engineering IV’s fire protection capabilities: 1) Structural Fire Resistance, 2) Egress Compliance, 3) Fire Suppression System, 4) Fire Alarm System, and 5) Smoke Management System.
This building was built in 2008 as a Type IIA construction in accordance with the 2001 California Building Code (CBC) which closely follows the International Building Code (IBC) requirements. This type designation requires specific fire resistance ratings for structural and other key components of the building. For the structural and structural supporting components, the fire resistance rating is two hours. This requires fireproofing throughout the steel frame structure of the building. The construction as-built drawings show that this was done in accordance with the appropriate codes. Although, the building was designed and built in accordance with 2001 building codes, the requirements regarding the structural fire resistance remain the same and are therefore compliant with existing code.
The egress aspects of Engineering IV are compliant with the current NFPA 101, Life Safety Code (LSC). The number of exits on each of the floors are appropriate relevant to the designed occupation quantity. The first floor has 15 exit discharges many of which are available through individual classrooms, laboratories, and assembly rooms. The second floor has three
exits to external stairwells that are unenclosed to the outside environment. This is appropriate for the designed occupancy of 500 people. The third floor has two exits to the external stairwells which are also appropriate for occupancies of below 500. Travel distances for common path (<100 ft) and distance to exit discharges (<300 ft) are in accordance with the current NFPA LSC (see Chapter 39). Other various egress requirements such exit signage, panic hardware for example are also compliant to code.
The building has a water-based fire suppression sprinkler system installed throughout the building. The location, spacing, and type of sprinklers used are compliant relative to the occupancy type of the building in accordance with NFPA 13, Standard for the Installation of Sprinkler Systems. The water supply was adequate for the sprinkler water demand calculated by the fire protection engineer at the time of construction. A current sprinkler system survey and demand calculation should be performed and compared to the latest hydrant flow test to verify system performance requirements.
There is an appropriate fire alarm and notification system installed in the building compliant with the NFPA 72 National Fire Alarm and Signaling Code. Although, the current NFPA 72 edition is 2019 and the building was designed using the 1999 edition, the fundamental components of the current system are compliant with current code. The fire alarm control panel is connected to a network of initiating devices such as smoke detectors, and notification devices such as horns and strobe lights. In addition, the as-built wiring diagram shows the fire alarm panel to be connected through relays to critical components of the building such as the elevator, HVAC, and smoke barrier systems.
Finally, the building includes a passive smoke management system as required by the IBC for buildings with atrium features connecting three or more floors. This is compliant with both the IBC and NFPA 92, Standard for Smoke Control systems. The smoke management system of the building includes a smoke housing compartment at the top of the main stairwell on the third floor. There is a smoke release door installed for the entrance and exit of this compartment onto the main stairwell of the building. The smoke release doors are normally open and will close upon a signal from the fire alarm system. There are also architectural openings on the second and third floor corridors that provide natural lighting throughout the three-story building. These natural lighting features on the third floor have hidden smoke barriers that actuate and close upon fire alarm signal from the building’s fire alarm control panel.
The prescriptive analysis of this report will show that the building is compliant relative to the applicable building and safety codes regarding fire protection safety. However, this aspect alone does not guarantee that occupants of a building can evacuate the area of the fire or the building before they encounter hazardous or untenable conditions. The performance analysis will provide data that will or will not support this premise.
The performance analysis portion of this report is meant to prove whether occupants can safely exit the area of the fire or the building before untenable conditions occur. A final comparison of the Required Safety Egress Time (RSET) and Available Safe Egress Time (ASET) will help support the overall assessment. The results of this report vary in accordance with the Design Fires as developed in this report. In some cases, the RSET overlap the ASET meaning that there is a significant potential of development of untenable conditions before all occupants can leave the building. In other Design Fires, the ASET exceeded the RSET and support the premise that occupants could evacuate in a safe and timely manner. These untenable conditions consist of effects from temperature, heat flux, carbon monoxide poisoning, and diminishment of smoke visibility as described in the Society of Fire Protection (SFPE) Handbook 5th edition, through various studies. The complexity of this analyses required the use of computer modeling applications which in this case was the Fire Dynamics Simulator (FDS) and PyroSim applications. FDS provides the calculations to support the modeled results, while PyroSim provides the front end to operate FDS and visualization of the results.
The Design Fires included in this report and used as input to the FDS application will provide the scenarios and fire characteristics that are believed by the author to be most likely within the guidelines of NFPA 101, Life Safety Code. The Design Fires used in this report are the following: 1) Design Fire 1 – Atrium Lobby, 2) Design Fire 2 – Classroom on 1st Floor, 3) Design Fire 3 – Faculty Office on Second Floor, and 4) Design Fire 4 – Atrium Lobby with Smoke Management System Failure.
Assumptions are provided along with these design fires to limit the range of the many variables to a reasonable level. The fire model results in this report are estimates of how a design fire will react. The results are meant to be used to assess what actions could be taken to improve fire emergency reaction. Exact fire scenarios cannot be predicted.
The RSET estimating method for this building was calculated using the hydraulic flow method as identified in the SFPE Handbook (Chapter 59). This report estimates that occupants should be able to evacuate the entire building in less than 90 seconds. This is an optimum estimate based the assumption that occupants can move at the maximum estimated speeds. The first untenable condition that appeared in all the Design Fire scenarios through FDS are the diminished smoke visibility. Studies have shown that visibility due to smoke densities less than approximately 10 meters may lead to hesitation of occupants during egress. This has a potential of delaying evacuation. Using a model simulation time of 480 seconds, the diminished visibility condition became the earliest untenable factor in these design fires. In the scenarios of Design Fires 1 and 4, untenable conditions in the form of diminished visibility occur before occupants can evacuate the building. Design Fires 2 and 3 show that occupants should be able to completely evacuate the building before untenable conditions occur. In these scenarios, diminished visibility is the first untenable condition to occur again.
These RSET vs ASET quantitative results alone should not be used as a definitive answer to the question of whether occupants will evacuate the building safely or not. This analysis is meant to identify areas of needed improvement to support successful protection of occupants trying to evacuate the building during a fire event. These results are based on assumptions of a specific fire with a specific fuel, occupant movement, whether doors are open or not, and many other variables. Actual fire events cannot be predicted with that kind of precision. However, these results can be used to help improve the probabilities of preventing harm from a fire event. That analysis will be provided in the body of this report.
Specific recommendations relative to each Design Fire are provided later in this report. General recommendations that effect Engineering IV are as follows: 1) hire an independent Fire Protection Engineer to perform an entire building survey, 2) perform new Hydrant Flow Tests, 3) establish or review Emergency Management Plans, and 4) train University staff for fire emergency events.