MS in Fire Protection Engineering
College of Engineering
Frederick Mowrer and Christopher Pascual
The subject building of the report is an outpatient healthcare system building that is a two stories in height and 184,670 SF building. This building offers primary, specialty, and mental health outpatient care to patients throughout its state of location.
The facility is a mixed occupancy building with business as the primary occupancy, a surgery suite that classifies as an ambulatory health care occupancy, and assembly uses in the conference rooms, kitchen, and canteen. The Authority Having Jurisdiction (AHJ) has adopted the National Fire Codes (NFC) published by the National Fire Protection Association (NFPA), and throughout this report, the life safety features of the building are assessed against the requirements of Life Safety Code, NFPA 101.
The facility is fully sprinklered, with sprinklers appearing to be provided in all areas. There is also an analog addressable fire alarm system that is electrically supervised by a central station monitoring service. Per NFPA 220, Standard on Types of Building Construction, Table 4.1.1 Fire Resistance Ratings for Type I through Type V Construction (hour), this facility appears to be constructed in accordance with the requirements of a Construction Type II (000) rating. The NFPA Type II (000) rating corresponds to an IBC Construction Type IIB.
In the following analysis, the facility was evaluated from both prescriptive and performance based design perspectives.
The total occupant load for the facility was calculated as 3390 persons in accordance with NFPA 101 Chapter 7. Most spaces were determined to have adequate exit capacity. However, the canteen only has one valid exit and does not meet the required two exits per NFPA 101 for assembly occupancies. All other floors and spaces were determined to have adequate number of exits, separation of exits, and measured travel distances as required by NFPA 101.
Code discrepancies were also discovered for fire detection and notification. A discrepancy was discovered between the mounting heights of manual pull stations required by NFPA 72 and those of the fire alarm and detection shop drawings. Pull station placement should be verified. Notification devices in the mechanical penthouses appear to be undersized from a visual notification perspective. Further, audible notification devices in these mechanical penthouses may also be undersized. Field verification of the existing ambient sound levels should be performed.
The facility is fully sprinklered, with sprinklers appearing to be provided in all areas. Most of the facility is protected by an automatic wet sprinkler suppression system. There is a small dry sprinkler system located at the loading dock, where the system is subject to freezing conditions. The system appears to have been designed per the AHJ’s Fire Protection Design Manual and NFPA 13-2003.
The flow and pressure at the base of the riser (BOR) required to meet the sprinkler system demand is 273.3 gpm and 67.6 psi. The hose stream allowance was previously determined to be 250 gpm. Therefore, the total system demand is 523 gpm at 67.6 PSI. This value exceeds the available water supply of a static pressure of 62 psi, a residual pressure of 20 psi, and 1940 gallons of flow. A computer based analysis should be performed to refine the understanding of the complex hydraulics at the facility.
The first floor occupant load was calculated to be 839 persons. Using the hydraulic approximation, the egress time for the first floor was evaluated. If all of the 839 occupants on the first floor start evacuation at the same time, the persons on the first floor will require approximately 1.23 minutes to pass through the exit. The total minimum evacuation time for the 839 persons located on floor 1 is estimated at 5.1 minutes.
The second floor occupant load was calculated to be 1210 persons. The second floor exit capacity was calculated to be 1231 persons, which just exceeds the second floor occupant load of 1210 persons. The total minimum evacuation time for the 1231 persons located on floor 2 is estimated at 8.2 minutes. The assumptions used in hydraulic approximation model all tend to optimize egress times and therefore will tend to underestimate actual egress times.
The occupant characteristics of these user groups within the facility’s building population were reviewed, and the key characteristics of the groups were evaluated. Since the purpose of this outpatient clinic is to provide medical care to patients, a conservative approach is necessary to protect occupants that may have preexisting medical conditions. Employees regularly participate in fire drills and can typically be expected to efficiently respond to the fire alarm system and start evacuating. However, careful consideration of pre-movement times is especially important with employees as they can be prone to social influence, and procedural requirements. Patients are the most likely to have an issue perceiving an alarm, interpreting the alarm, and deciding on a course of action.
Three different design fires were evaluated for this facility. Design Fire #1 investigates the impact of large fuel load of palletized computer equipment on egress in a first floor corridor. Egress is expected to be highly compromised. This design fire is similar to NFPA 101 18.104.22.168 Design Fire Scenario 2 which has the characteristics of an ultrafast developing fire, in the primary means of egress.
Design Fire #2 investigates the impact of a Christmas Tree in the building’s main atrium. This fire offers the opportunity to evaluate the impact of a real life fuel load on one of the primary egress paths. This design fire is similar to NFPA 101 22.214.171.124 Design Fire Scenario 1 and is an occupancy specific fire representative of a typical fire for the occupancy.
Design Fire #3 evaluates the impact of a large fuel load of furniture in a storage room that is adjacent to the facilities 6 combinable conference rooms. The worst-case scenario for this space is the potential for migration into the adjacent hallway and affecting egress for the nearby conference rooms. This design fire is similar to NFPA 101 126.96.36.199 Design Fire Scenario 3 which includes a fire that starts in a normally unoccupied room, potentially endangering a large number of occupants in a large room or other area.
Performance criteria for tenability was investigated, and reference values were proposed. The selected tenability criteria include 13 m for visibility, an FED of 1 for Carbon Monoxide, 60 °C for exposure temperature, and 1.7 kW·m-2 for radiant heat exposure. Fire Dynamics Simulator (FDS) was used to model Design Fire #1, which presented an abnormally large fuel load of computer equipment in a hallway outside of the Supply Chain Management office. This fire provides an ultrafast developing fire, in the primary means of egress, and addresses a concern regarding a reduction in the number of available means of egress.
Visibility is the first tenability criteria to be reached in a time frame of 92 seconds, followed by exposure temperature at 105 seconds. The reality of this ultrafast fire is that egress for the Supply Chain Management Office will be severely compromised, and may not provide ample time for the occupants of the Supply Chain Management Office to escape. Further modeling could be performed with additional information on the building's construction materials, ventilation systems, and fire suppression systems. The response of the fire suppression system, and its effectiveness on the fuel load should be evaluated and could potentially help egress from the Supply Chain Management Office. Since the calculated Required Safe Egress Time (RSET) is calculated 12.72 minutes, and the Available Safe Egress Time (ASET) is 92 seconds, egress for the Supply Chain Management Office can be expected to be compromised.
Based on the results of modeling Design Fire #1, it is recommended to relocate the commodity to a warehouse. The surveyed fuel load is inappropriate for an exit corridor in a Business Occupancy.