Technical Conference on the NIS

Building and Fire Safety Investig

World Trade Center Disas

September 14, 2005

Project #4: Investigation of Active Fire Prote

Smoke Control Systems Sub-Task (NCS

3610 Commerce Drive, Suite 817, Baltimore, MD 

Phone:410-737-8677 Fax:410-737-8688 We

www.haifire.com

Michael J. Ferreira, P.E.

Steven M. Strege
NIST WTC Investigation NIST WTC Investigation 

Project #4: Investigation of Active Fire P

Project #4: Investigation of Active Fire P

Systems Smoke Control Systems Sub Systems Smoke Control Systems Sub

-T

Purpose:Investigate the performance of the active fisystems in WTC 1, 2, and 7 and their role iemergency response, and fate of occupantresponders.
NIST WTC Investigation NIST WTC Investigation 

Project #4: Investigation of Active Fire P

Project #4: Investigation of Active Fire P

Systems Smoke Control Systems Sub Systems Smoke Control Systems Sub

-T

Goals and Objectives:1) Document the design and installation of t

management systems installed in WTC 1compare the designs to applicable code arequirements (Task 1).

2) Document the normal operation of the ful

smoke management systems, and its potsmoke conditions in WTC 1 and 2 on Sep(Task 2).
NIST WTC Investigation NIST WTC Investigation 

Project #4: Investigation of Active Fire P

Project #4: Investigation of Active Fire P

Systems Smoke Control Systems Sub Systems Smoke Control Systems Sub

-T

Approach: Identify applicable code requirements with respect 

management systems.

• NCSTAR 1-1D Report

 Describe operation of smoke management system

• Building operations manuals (NIST Document Re• Port Authority input

 Evaluate system performance on September 11, 2

• Actions of emergency response personnel• Damage to system components

 Evaluate potential smoke management system eff

• Use CONTAM building air

flow model t

o evalu

ate 

management system approaches for various des
Task 1: Summary of Installed Smoke Ma

Task 1: Summary of Installed Smoke Ma

Features in WTC 1 and 2 Features in WTC 1 and 2

 WTC 1 and 2 provided with the means for accomp

purge from each HVAC zone in the building.

 Fire dampers required at all duct openings into ver

and at penetrations of fire resistance rated floors a

 Provision of multiple fire compartments on each flo

(not required once sprinklers were installed). [LL#5

 One or more smoke shafts by which smoke could 

vented to the outdoors. In lieu of smoke shafts stawith stair pressurization. [LL#5]

• Pil

ot study performed between 1976 and 1979 to eva

providi

ng stair pressurization systems in WTC 1 an

• LL#86 (enacted in 1979) exempted buildings from s

pressurization requirem

ent if they we

r

e sprinkler

e

d 

• Stair pressurization systems never installed i

n WTC 
Task 1: Summary of Installed Smoke Ma

Task 1: Summary of Installed Smoke Ma

Features in WTC 7 Features in WTC 7

 Fire dampers required at all duct openings into ver

and at penetrations of fire resistance rated floors a

 Combination fire/smoke dampers or an independe

fire resistance rated penetrations.

 A mechanical means to exhaust 6 air changes per 

from the largest floor of the building.

• Smoke purge quantities found to be not consistent 

specified by code (48,000 cfm). Low on floors up to 

High on r

enovated upper floors of the building (84,0

 Emergency power system having the capacity to o

related equipment, including smoke purge equipm

 No evidence found to show smoke purge utilized o

building was evacuated, systems had minimum effoccupants/emergency responders.
WTC 1 and 2 WTC 1 and 2 – Building Ventilation 

Building Ventilation 

 Each tower had four 

two-level mechanical equipment rooms.

 Four major HVAC 

zones within each building.
WTC 1 and 2 WTC 1 and 2 – Building Ventilation 

Building Ventilation 

SUPPLY PLENUM

SUPPLY PLENUM

SUPPLY PLENUM

SUPPLY PLENUM

MER – Lower Level MER – U
WTC 1 and 2 WTC 1 and 2 – Building Ventilation 

Building Ventilation 
WTC 1 and 2 WTC 1 and 2 – Smoke Managemen

Smoke Managemen

Sequence of Operations Sequence of Operations

 Fire Safety Plan for WTC 1 and 2 (PANYNJ 1999) 

smoke purge “after a fire has been extinguished”. achieved by aligning equipment from within an indcentral control panel located in the Operations ConB1 level of WTC 2.

 WTC Instruction 

Manual No. 23, Operation and Maintenance of Fire Protection Systems (PANYNJ 1986) documents sequence of operations as follows ->

Towers A and B

Interior AreasNote: Only the Fire Safety Director on duty may r

smoke purge.

In the event of smoke in an interior tenant’s space ipersonnel evacuation, the smoke purge procedure tfollows:1. Secure all fans in the pertinent MER.2. Set all quadrant Normal/Purge/Reset switches to position.3. Start all return air fans.4. Start MER exhaust fan(s), if necessary.Tower Core1. Secure all fans in the pertinent MER.2. Set all quadrant Normal/Purge/Reset switches to position.3. Start all return air fans.4. Open Men’s and Ladies’ Room doors on the floorelevant toilet exhaust fan(s).
WTC 1 and 2 WTC 1 and 2 – Smoke Managemen

Smoke Managemen

Sequence of Operations Sequence of Operations

 PANYNJ was asked to clarify the operation of the 

sequence. The response was as follows:“If fans were still operating, as would often be the case, the direction would key over to purge mode. This would sequen100 %. In addition, building operating procedure during a pu

interior supply fans for purging [the] affected quadrant. Durfan’s outside supply air dampers would go to 100 % open.... 

normally operate during a smoke purge unless conditions wby FDNY.”

 PANYNJ stated that WTC Instruction Manual No. 2

updated after the 1993 bombing and did not alwaycurrent fire protection system configuration.

 Accounts of February 13, 1975 fire on 11th floor of 

“smoke purge” sequence as the core being pressuspaces being exhausted. The accounts further stapurge sequence for the HVAC zone containing the initiated during the fire.
WTC 1 and 2 WTC 1 and 2 – Evaluation of Smoke Man

Evaluation of Smoke Man

System Performance on September 11, 

System Performance on September 11, 

Actions of Emergency Response Personnel WTC fire safety director on duty on Septembe

that no recommendation was given on his pasmoke purge sequence, nor was smoke purgknowledge.

 No record was found of FDNY personnel hav

smoke purge sequence in WTC 1 or WTC 2.
WTC 1 and 2 WTC 1 and 2 – Evaluation of Smoke Man

Evaluation of Smoke Man

System Performance on September 11, 

System Performance on September 11, 

Damage to System Components While the extent of damage to individual floor

may never be known, the potential damage cbased on the results of engineering analysis apeople within the buildings.

 Numerous accounts are available documentin

the three stair shafts in each building and extcore areas, where HVAC and electrical systewere located.

 Extensive damage to HVAC ductwork system

was the loss of electrical power. HVAC syste2 were not provided with emergency power.
WTC 1 and 2 WTC 1 and 2 – Evaluation of Smoke Man

Evaluation of Smoke Man

System Performance on September 11, 

System Performance on September 11, 

Damage to System Components
WTC 1 and 2 WTC 1 and 2 – Evaluation of Smoke Man

Evaluation of Smoke Man

System Performance on September 11, 

System Performance on September 11, 

Damage to System Components
WTC 1 and 2 WTC 1 and 2 – Evaluation of Smoke Man

Evaluation of Smoke Man

System Performance on September 11, 

System Performance on September 11, 

Damage to System Components
WTC 1 and 2 WTC 1 and 2 – Evaluation of Poten

Evaluation of Poten

Management System Effectivenes

Management System Effectivenes

 The CONTAM building airflow and contaminant dis

(developed by NIST) was used to evaluate how vamanagement system configurations might have peSeptember 11, 2001. 

 The performance of these systems for other hypot

in high-rise buildings was also evaluated.

 Performance criteria – creation of pressure differe

zones.

 Smoke management approaches evaluated:

• Smoke Purge• Core Pressurization• Building Pressurization• Sandwich Pressurization• Zoned Smoke Control with Stair Pressurization

 High-rise fire scenarios evaluated:

• Sprinklered Fire• Full-Floor Burnout• Two-Floor Fire• 9/11/01 Fire Scenario (No shaft damage)• 9/11/01 Fire Scenario (Shaft damage assumed)
WTC 1 and 2 WTC 1 and 2 – Evaluation of Poten

Evaluation of Poten

Management System Effectivenes

Management System Effectivenes

Conclusions: The smoke purge system installed in WT

only have been effective in containing smsprinklered fire.

 The zoned smoke control with stair press

approach would be effective for typical hiscenarios but may be impacted by stack buildings such as WTC 1 and 2.

 None of the postulated smoke managem

would have been effective for the Septemimpact scenario.
NIST WTC Investigation NIST WTC Investigation 

Project #4: Investigation of Active Fire P

Project #4: Investigation of Active Fire P

Systems Smoke Control Systems Sub Systems Smoke Control Systems Sub

-T

Findings:1) The smoke management systems in WTC

1 a

provided the capability for a manual smoke pindividual HVAC zone on a quadrant-by-quadnot initiated on September 11, 2001.

2) Had the smoke purge sequence been initiate

WTC

2, it is unlikely the system would have f

designed, due to loss of electrical pow

er and/

HVAC shafts and other structural elements in 

3) Provision of active smoke management syste

combination fire/smoke dampers was not reqBCNYC or retroactive provisions in the variouenacted after WTC

1 and WTC

2 were constr

high-rise buildings provided with automatic spthroughout.
NIST WTC Investigation NIST WTC Investigation 

Project #4: Investigation of Active Fire P

Project #4: Investigation of Active Fire P

Systems Smoke Control Systems Sub Systems Smoke Control Systems Sub

-T

Findings:4) None of the potential smoke management sys

evaluated in this report would have provided differentials to contain smoke for the postulatdamage scenarios, even if these systems weoperation after the building sustained damage impact. 

5) The smoke purge sequence in existence on o

September 11, 2001, would have been expecof limiting the spread of smoke from the zone for fire scenarios in which the sprinkler system and controlled the fire. Other smoke managecapable of being implemented using the existWTC

2 ventilation systems may also have be

controlling smoke from the postulated full-floofloor fire scenarios evaluated in this report habeen identified and implemented into the seqoperations. 
NIST WTC Investigation NIST WTC Investigation 

Project #4: Investigation of Active Fire P

Project #4: Investigation of Active Fire P

Systems Smoke Control Systems Sub Systems Smoke Control Systems Sub

-T

Findings:6) During the events occurring on September 11

pressurization would have been ineffective in conditions for occupants trying to exit the buil

7) Installation of combination fire/smoke dampe

ductwork, which was not required in WTC

1 o

have acted to slow the development of hazarthe uppermost floors of the building, but woulhad a significant effect on the ability of occupbuilding due to the impassibility of the exit sta