NISTIR 6854 

Simulation of the Dynamics of a Fire in a Two-Story Duplex - 

Iowa, December 22, 1999

 Daniel Madrzykowski 

Glenn P. Forney 

 William D. Walton 
NISTIR 6854 

Simulation of the Dynamics of a Fire in a Two-Story Duplex – 

Iowa, December 22, 1999 

Daniel Madrzykowski 

Glenn P. Forney 

 William D. Walton

Building and Fire Research Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-8661

January 2002 

U.S. Department of Commerce 

Donald D. Evans, Secretary 

Technology Administration 

Phillip J. Bond, Under Secretary for Technology 

National Institute of Standards and Technology 

Arden L. Bement, Jr., Director 
iii

TABLE OF CONTENTS 

List of Tables......................................................................................................................... iv 

List of Figures.........................................................................................................................v 

1. ABSTRACT........................................................................................................................... 1

2. INTRODUCTION................................................................................................................. 2

3. FIRE INCIDENT SUMMARY............................................................................................ 2

4. NIST FIRE DYNAMICS SIMULATOR (FDS)................................................................ 3

4.1. MODEL UNCERTAINTY..................................................................................................... 3 

5. SMOKEVIEW....................................................................................................................... 4

6. FDS INPUT............................................................................................................................ 4

6.1. GEOMETRY ...................................................................................................................... 5 

6.2. VENTS.............................................................................................................................. 5

6.3. MATERIAL PROPERTIES ................................................................................................... 7 

6.4. IGNITION FIRE.................................................................................................................. 8 

7. MODEL RESULTS .............................................................................................................. 8

7.1. STRUCTURE AND CONTENTS SIMULATION ....................................................................... 8 

7.2. FIRE SIMULATION - TEMPERATURE PREDICTIONS............................................................ 9 

7.2.1. FLAME SHEET FIRE SIMULATION ............................................................................... 10 

8. SUMMARY ......................................................................................................................... 10

9. REFERENCES.................................................................................................................... 11

10. ACKNOWLEDGEMENTS ........................................................................................... 11
iv

LIST OF TABLES 

Table 1. Approximate Incident Timeline....................................................................................... 5

Table 2. Time of Ventilation Events for FDS Simulation ............................................................. 6 

Table 3. Thermal Properties Data .................................................................................................. 7 

Table 4. Furniture Materials and Size............................................................................................ 8 
v

LIST OF FIGURES 

Figure 1. Front of structure. Duplex on right was the unit of fire origin..................................... 12 

Figure 2. Back of structure........................................................................................................... 12 

Figure 3. Plan view of 1st Floor. Ceiling height of 1st floor 2.8 m, except for kitchen area, 2.4 m.

............................................................................................................................................... 13 

Figure 4. Plan view of 2nd Floor. Ceiling height 2.4 m............................................................... 14 

Figure 5. Results of fire extension from kitchen window up to rear bedroom. ........................... 15 

Figure 6. Inside view of kitchen, area of origin........................................................................... 15 

Figure 7. Dining Room with table and chairs.............................................................................. 16 

Figure 8. Living room with sofa from front hall doorway........................................................... 16 

Figure 9. 1st floor hall with doorway to living room on left & front doorway on right............... 17 

Figure 10. Stairway and 1st floor hall from front doorway.......................................................... 17 

Figure 11. Second floor landing and stairwell looking toward front of structure........................ 18 

Figure 12. Rear bedroom above kitchen...................................................................................... 18 

Figure 13. Right front of duplex. Front bedroom window shown with lower portion open. Front 

door shown closed. The outer box frame represents the boundary of volume modeled...... 19 

Figure 14. Yard side of duplex. Outer wall removed to show living room and dining room on 

the first floor and front and middle bedrooms on the second floor. ..................................... 19 

Figure 15. Rear of duplex. The kitchen, with stove and cabinets, and a bathroom are shown on 

the 1st floor, the rear bedroom, above the kitchen, and a bathroom are on the 2nd floor....... 20 

Figure 16. Shared side of duplex. The rear of the duplex is on the left of the figure. From the 

left, a bathroom, the kitchen, a closet under the stairs, the stairway and lower hall can be 

seen on the 1st floor. Also from the left, a bathroom, upper hall and front bedroom can be 

seen on the 2nd floor. ............................................................................................................. 20 

Figure 17. Example of 3 dimensional grid arrangement.............................................................. 21 

Figure 18. Thermal conditions at approximately 8:32 AM (491 s into simulation).................... 21 

Figure 19. Thermal conditions at approximately 8:33 AM (524 s into simulation).................... 22 

Figure 20. Thermal conditions at approximately 8:34 AM (605 s into simulation).................... 22 

Figure 21. Estimated flame boundary covering stove top at approximately 8:28 AM................ 23 

Figure 22. Estimated flame boundary extending across kitchen ceiling and venting out of upper 

portion of kitchen window at approximately 8:32 AM. ....................................................... 23 

Figure 23. Estimated flame boundary spreading through the dining room and into the living 

room at approximately 8:33 AM. Flames continue to spread up the outside of the kitchen.

............................................................................................................................................... 24 

Figure 24. Estimated flame boundary spreading through the dining room and into the living 

room at approximately 8:34 AM........................................................................................... 24 
1

Simulation of the Dynamics of a Fire in a Two-Story Duplex, 

Iowa, December 22, 1999 

Daniel Madrzykowski 

Glenn P. Forney 

William D. Walton 

1. ABSTRACT 

This report describes the results of calculations using the NIST Fire Dynamics Simulator 

(FDS) that were performed to provide insight on the thermal conditions that may have 

occurred during a fire in a two-story duplex house on December 22, 1999 in Iowa. Input to 

the computer model was developed from 3 sources; investigators from the Bureau of 

Alcohol Tobacco and Firearms (ATF), investigators with the National Institute for 

Occupational Safety and Health (NIOSH) and from material properties taken from the FDS 

database. 

An FDS model scenario was developed that best represented the actual building geometry, 

material thermal properties, and fire behavior based on information and photographs from 

ATF. The results from this model scenario are provided with this report. 

The FDS calculations that best represent the reported fire conditions indicate that a fire 

originating on the kitchen stove spread through the house resulting in flames that engulfed 

the stairwell to the second floor within approximately 9 minutes from the start of flaming 

ignition on the stove. 

The critical event in this fire was the onset of flashover conditions in the kitchen. Within 

60 s after the flashover occurred in the kitchen, the flames had spread through the dining 

room, living room and up the stairway. 

Key Words: cfd models; computer graphics; fire dynamics; fire fatalities; fire fighters; fire 

investigations; fire models; flashover; ventilation 
2

2. INTRODUCTION 

Part of the mission of the Building and Fire Research Laboratory (BFRL) at the National 

Institute of Standards and Technology (NIST) is to conduct basic and applied fire research, 

including fire investigations, for the purposes of understanding fundamental fire behavior 

and to reduce losses from fire. 

On December 22, 1999 a fire in a two story duplex house in Iowa claimed the lives of three 

children and three firefighters. The fire occurred in the right half of a two story duplex as 

shown in Figure 1. In this figure, the entry doors to the two units are located next to each 

other, under the porch roof on the left side of the photograph. The backside of the house is 

shown in Figure 2. The heavily damaged area on the 1st floor is the kitchen and the area 

above on the 2nd floor is the rear bedroom. Plan views of the first and second floor are 

shown in figures 3 and 4. 

At the request and under the sponsorship of the National Institute for Occupational Safety 

and Health (NIOSH), NIST has examined the fire dynamics of this incident. NIST has 

performed computer simulations of the fire using the newly developed, NIST Fire 

Dynamics Simulator (FDS) and Smokeview, a visualization tool, to provide insight on the 

fire development and thermal conditions that may have existed in the residence during the 

fire. This report describes the input and the results of the NIST FDS Version 1.0 

calculations. 

3. FIRE INCIDENT SUMMARY 

This account of the events relevant to this fire is based on information provided to NIST by 

the Bureau of Alcohol, Tobacco and Firearms (ATF) and NIOSH. 

On the morning of December 22, 1999, a fire started in plastic materials on top of the stove 

in the kitchen on the first floor of the residence. An adult occupant, sleeping upstairs in the 

front bedroom, awoke to the cries of a child. The adult opened the front bedroom door to 

the hall and found hot smoky conditions. The adult returned to the front bedroom, opened 

a window on the front side of the house and called for help, alerting several neighbors. It is 

believed that the calls to 911 began shortly after this. The first call was received by the 

dispatcher’s office at approximately 8:24 AM. The adult returned to the smoky upstairs 

hallway, found the crying child and exited the residence by the front bedroom window onto 

the roof of the front porch. Approximately two minutes later, 8:26 AM, firefighters and 

police began to arrive at the fire scene. The smoke plume was visible as firefighters 

approached the scene and there was little if any wind disturbing the plume. The adult 

occupant was outside with the child and explained that there were three children still in the 

house. The front door to the residence was forced open by a police officer at 

approximately 8:27 AM. The officer discovered heavy smoke conditions. He could not 

make entry into the house. At 8:28 AM, the first arriving crew of firefighters prepared to 

enter the residence and placed a call requesting additional firefighters. At approximately 

8:31 AM, the Fire Chief arrived at the fire scene with an additional firefighter. Three fire 

fighters entered the house and brought two infants from upstairs bedrooms to the front 
3

door. Two police vehicles were used to transport the infants to the hospital. The fire chief 

was administering CPR to the second infant and was transported to the hospital. Based on 

radio transmissions, the first infant was enroute to the hospital at approximately 8:34 AM 

and the second infant was enroute to the hospital at approximately 8:35 AM. According to 

witness statements, the full fire involvement of the living room, leading to a fully involved 

fire condition in the stairwell, occurred as the infants were being transported to the hospital. 

A hose line had been advanced into entry foyer of the house. The “dry” hose line was 

placed on the floor, while the firefighter returned to the engine to charge the line. When 

the hose line was “charged” (pressurized with water) it was discovered that the hose had 

burned through and flames were coming out of the doorway to the house. 

At approximately 8:48 AM, as a second fire crew made entry into the house and began to 

attack the fire with a hose line, a firefighter was discovered on the floor of the living room. 

Later the other two firefighters from the first crew were found on the second floor. One on 

the landing at the top of the stairs with a child victim and another in the doorway of the 

front bedroom. All three firefighters and the one child found in the house, and the two 

children taken to the hospital died from injuries caused by the fire. 

 

The post fire investigation confirmed that the fire started in plastic material on the stove. 

The kitchen had fire damage throughout, consistent with a well-mixed, post-flashover fire 

environment, Figures 5 and 6. In addition to the kitchen area, there was significant fire 

damage in the living room (Figure 8), the stairwell, second floor hallway (Figures 9-11) 

and the rear bedroom above kitchen (Figure 12). The dining room (Figure 7), the other 

bedrooms and the bathrooms had less fire damage than the other portions of the house. A 

timeline of the fire events is given in Table 1. 

4. NIST FIRE DYNAMICS SIMULATOR (FDS) 

NIST has developed a computational fluid dynamics (CFD) fire model using large eddy 

simulation (LES) techniques [1]. This model, called the NIST Fire Dynamics Simulator 

(FDS), Version 1., has been demonstrated to predict the thermal conditions resulting from a 

compartment fire [2,3]. A CFD model requires that the room or building of interest be 

divided into small three-dimensional rectangular control volumes or computational cells. 

The CFD model computes the density, velocity, temperature, pressure and species 

concentration of the gas in each cell. Based on the laws of conservation of mass, 

momentum, species and energy the model tracks the generation and movement of fire 

gases. FDS utilizes material properties of the furnishings, walls, floors, and ceilings to 

compute fire growth and spread. A complete description of the FDS model is given in 

reference [1]. 

 

4.1. Model Uncertainty 

FDS can provide valuable insight into how a fire may have developed. However the model 

is only a simulation. The model output is dependent on a variety of input values such as 

material properties, times lines, geometry, and ventilation openings. Since perfect 

knowledge of every detail of the fire site, fuel load or fire timeline is never known, 
4

estimations are incorporated into the model. For example, the estimation of the energy 

release rate of an initial “source fire” as a starting point for fire development and spread 

throughout the structure is a necessary part of re-creating this fire scenario. Another 

estimation used in this case, the plaster ceilings and walls of the structure were modeled 

with the thermal properties of gypsum board. These estimations and others used in this 

simulation are further described in Section 6 of this report. 

The ability of the FDS model to accurately predict the temperature and velocity of fire 

gases has been previously evaluated by conducting experiments, both lab-scale and fullscale, and measuring quantities of interest. For relatively simple fire driven flows, such as 

buoyant plumes and flows through doorways, FDS predictions are within the experimental 

uncertainty of the values measured in the experiments [2]. For example, if a gas flow 

velocity is measured at 0.5 m/s with an experimental uncertainty of ±0.05 m/s, the FDS 

model gas flow velocity predictions were also in the range between 0.45 m/s and 0.55 m/s. 

In large scale fire tests reported in [3], FDS temperature predictions were found to be 

within 15 % of the measured temperatures and the FDS heat release rates were predicted to 

within 20 % of the measured values. Therefore the results are presented as ranges to 

address these uncertainties. 

5. SMOKEVIEW 

Smokeview is a scientific visualization program that was developed to display the results of 

a FDS model computation. Smokeview produces animations or snapshots of FDS results 

[4]. 

A new feature of Smokeview allows the viewing of FDS output in 3-dimensional 

animations. An iso-surface is a three dimensional version of a contour elevation often 

found on topographic maps. In this report, a beta version of Smokeview was used in 

conjunction with FDS Version 1.0 to generate animated iso-surfaces to visualize the 

movement and spread of the fire. 

6. FDS INPUT 

Inputs required by FDS include the geometry of the structure, the computational cell size, 

the location of the ignition source, the energy release of the ignition source, thermal 

properties of walls, ceiling, floors and furnishings, and the size, location, and timing of 

door and window openings to the outside which critically influence fire growth and spread. 

The timing of the door and window openings used in the simulation given in Table 2 are 

based on an approximate timeline of the fire events in Table 1. 
5

Table 1. Approximate Incident Timeline 

Incident 

Time 

Events Simulation 

Time 

(s) 

08:24 First call reporting fire. 0 

08:26 Fire fighters arriving on scene 120 

08:27 Front door open 180 

08:28 Fire fighters on scene requesting back-up 240 

08:31 Fire Chief arrives on scene 420 

08:33 Second infant removed from house by this time 540 

08:34 First infant enroute to hospital. 600 

08:35 Second infant enroute to hospital, hoseline burned 660 

08:48 Discovered fire fighter on 1st floor 

6.1. Geometry 

The floor plans of the first and second floor of the duplex are shown in Figures 2 and 3. 

The two levels of the duplex are enclosed within a 13.4 m (44.0 ft) x 6.0 m (19.7 ft) x 

5.4 m (17.7 ft) tall rectangular volume. For the FDS simulation this volume was divided 

into 64,800 computational cells. Each cell has dimensions of a 0.2 m (8 in) x 0.2 m (8 in) x 

0.2 m (8 in) cube. The size of the interior walls, doorways, and windows were based on the 

dimensions of the house. The size and location of the walls, doorways, and windows are 

adjusted by FDS to correspond to the nearest computational cell location. This results in 

walls, used in the model, that appear thicker then they are in the actual house and stairs that 

are not uniform throughout. 

6.2. Vents 

This simulation considered three vents or openings from the structure to the outside, the 

front window in the front bedroom, the front door and the kitchen window. The lower 

portion of the front window in the front bedroom had an opening approximately 0.8 m 

(2.6 ft) wide x 0.4 m (1.3 ft) high with a 0.4 m (1.3 ft) sill height. This vent was open 

during the entire simulation. The front doorway was 0.9 m (3.0 ft) wide x 2.2 m (7.2 ft) 

high. The front door opens at 180 s of simulation time. The kitchen window was 0.84 m 

(2.76 ft) wide and 1.4 m (4.6 ft) high with a 0.8 m (2.6 ft) sill height. The windows in the 
6

house were composed of small panes with wood framing in between each pane. With a 

window of this design, it typically would not fail or break-out all at once due to a fire. To 

account for partial breakage of the window and smoke leakage from the kitchen to the 

outside or other parts of the structure, the window vent opened in three sections. The upper 

most 0.2 m (8 in) section of the kitchen window opened at 90 s into the simulation. This 

opening is intended to account for smoke leakage out of the kitchen. The top half of the 

kitchen window opened at 270 s. This time was based on the gas temperatures being in 

excess of 400 °C (750 °F) near the upper portion of the window. The vent representing the 

kitchen window was completely opened at 510 s into the simulation. Again the window 

was opened based on the assumption that at 400 °C (750 °F) the wooden frame would be 

burning and creating excessive thermal stresses on the window glass [5]. 

Interior doorways were open with the exception of the following doors which were closed 

in the fire incident and therefore were also closed in the simulation: the door leading from 

the kitchen to the bathroom, the door to the closet in the dining room, the door between the 

dining room and the first floor hallway (see figure 3). On the second floor the door from 

the hallway to the bathroom was closed (see figure 4). 

At the time of the fire there was no wind, therefore for the simulation it was assumed that 

openings to the exterior were at ambient pressure. 

Table 2. Time of Ventilation Events for FDS Simulation 

Time of Event 

Vent Initial 

Conditions 90 s 180 s 270 s 510 s 

Front Bed Room 

Window Open Open Open Open Open 

Front Door Closed Closed Open Open Open 

Kitchen Window, 

Top 0.2 m (7.9 in) Closed Open Open Open Open 

Kitchen Window, 

Top Half Closed Closed Closed Open Open 

Kitchen Window, 

Bottom Half Closed Closed Closed Closed Open 
7

6.3. Material Properties 

The ceiling material was composed of combustible wood fiber ceiling tiles, with the 

exception of the dining room, which still had the original plaster on lathe ceiling. The 

ceiling tiles were attached to wood furring strips, which were attached to the bottom of an 

existing plaster on lathe ceiling. The plaster ceiling assembly was modeled with the 

thermal properties of gypsum board. 

The interior walls of the first and second floor hallways, the stairwell, bedrooms 2 and 3 

and the wall between bedroom 1 and bedroom 2 were covered with wood paneling and 

modeled as thin pine. All other walls were covered with gypsum board. 

The upstairs floor was modeled as pine. The downstairs floor was assumed to not 

contribute to the fire. 

Several large furniture items were included in the scenario; kitchen cabinets, kitchen table, 

dining room table, living room sofa and two upholstered chairs. The model inputs utilized 

for each material type are given below in Table 3 and the size of the furnishings are given 

in Table 4 [1,4]. 

Table 3. Thermal Properties Data 

Material Thickness 

(m) 

Ignition 

Temperature 

(°C) 

Heat 

Release 

Rate 

(kW/m2

)

Thermal 

Conductivity 

(W/m K) 

Thermal 

Diffusivity 

(m2/s) 

Ceiling Tile 0.025 330 300 0.14 8.3E-8 

Gypsum 

Board 0.013 400 100 0.48 4.1E-7 

Pine 0.013 390 200 0.14 8.3E-8 

Thin Pine 0.008 390 200 0.14 8.3E-8 

Upholstered 

Cushion 0.10 370 700 0.20 1.2E-6 

In addition to wood dining furniture, a cut evergreen tree was located in the Dining Room. 

The tree’s contribution to the fire was estimated by adding the heat release rate from a 2.5 

m tall, 1.2 m wide Scotch Pine with a mass of 9.5 kg [6]. The peak heat release rate was 

approximately 1.6 MW. This was the smallest tree used in the referenced study and it 

appeared to be the best representation of the tree that was in the house. As a point of 

reference, the maximum peak heat release rate from a burning cut pine tree measured in the 

referenced study was 5.2 MW. 
8

In the model, the tree is represented by a rectangular box, 1.26 m by 0.8 m and 0.2 m above 

the floor. The box is the source of the energy emitted by the tree, much like a gas burner. 

In one of the simulations, the tree was assumed to have ignited based on the thermal 

conditions in the dining room at 400 s. This did not significantly change the fire conditions 

in the structure and therefore the additional heat release rate input was eliminated from the 

final model simulation presented here. 

Table 4. Furniture Materials and Size 

Item Material Size 

Kitchen Cabinets, 

upper Pine 1.68 m wide, 0.4 m deep, 0.6 m high 

Kitchen Cabinets, 

lower Pine 1.68 m wide, 0.6 m deep, 0.9 m high 

Kitchen Table Pine 1.0 m wide, 1.05 m deep, 0.2 m thick, 

1.0 m high 

Dining Room 

Table Pine 1.26 m wide, 1.2 m deep, 0.2 m thick, 0.8 m high 

Sofa Upholstered cushion 1.6 m wide, 0.63 m deep, 0.8 m high 

Chairs (2) Upholstered cushion 0.84 m wide, 0.80 m deep, 1.20 m high 

6.4. Ignition Fire 

The fire started in plastic material on top of the stove. This fire source was approximated 

as a rectangular object representing the stove with a specified heat release rate coming out 

of a opening on the top. The “stove” can be seen in figure 15. The opening, which 

represents the fire area on top of the stove, is 0.4 m wide by 0.84 m deep and 1.0 m above 

the floor. The heat release rate of the fire was assumed to grow slowly, reaching a peak of 

approximately 400 kW in 270 s. The actual fire may have taken longer to develop; the 

actual ignition time of the fire is unknown. The simulation was started with a flaming 

ignition that corresponded to the approximate time at which the adult occupant and the 

neighbors became aware of the fire. 

 

7. MODEL RESULTS 

7.1. Structure and Contents Simulation 

Figure 13 shows a front perspective view of the right side unit of the duplex from the 

Smokeview model. The outer box frame lines represent the volume modeled. The solid 

base is used to indicate the inert first floor material. The closed front door, the partially 
9

open front bedroom window and the porch roof can be seen on the front side of the house. 

Figure 14 provides a side view of the model. The figure shows the front of the duplex on 

the left, moving to the right is the living room and then the dining room on the first floor. 

The front bedroom and middle bedroom can be seen on the second floor. The kitchen and 

rear bedroom are obstructed by the outside wall of the duplex on the far right. Significant 

pieces of furniture have been modeled on the first floor. Representations of a sofa and two 

chairs can be seen in the living room on the left side of the figure. The “floating square” in 

the dining room represents the dining room table and chairs. The kitchen window can be 

seen on the far right side of the house. Figure 15 provides a view of the simulated structure 

from the back. From this view the stove can be seen centered in the kitchen with the 

kitchen cabinets on the right side of the kitchen. The side of the house with the stairway is 

shown in figure 16. From the bottom left and moving toward the right on the first floor is a 

bathroom, the kitchen, a closet under the stairs and the entry foyer. On the second floor, 

another bathroom, the hall and open stairway and the front bedroom can be seen. The area 

on the far right represents an area outside the front of the house. The grid depicting the 

computational cell size is shown in figure 17. Each cell has dimensions 0.2 m (8 in) x 0.2 m 

(8 in) x 0.2 m (8 in). 

 

7.2. Fire Simulation - Temperature Predictions 

The simulation results in Figures 18 through 20 have had the outer walls removed to 

provide a clear view. The results are shown as a “slice” or a “plane” with a color bar that 

represents the corresponding numerical quantities. These figures provide “snapshots” of 

the calculated fire environment conditions that the firefighters may have been exposed to 

between 8:32 AM and 8:34 AM. 

Figures 18 and 19 show the plane of temperatures that align with the center of the kitchen 

and dining room doorways. This plane is located 2.9 m (9.5 ft) into the duplex from the 

outside wall of structure. The second temperature plane shown in the figures is located 

along the centerline of the kitchen window. 

In Figure 18, a distinct two-layer environment can be seen in the living and the dining room 

at 485 s into the simulation or approximately 8:32 AM. In the living room the upper or hot 

gas layer temperatures are approximately 200 °C to 300 °C (390 °F to 570 °F). In the 

dining room the hot gas temperatures are approximately 300 °C to 450 °C (570 °F to 

840 °F). In both rooms, temperatures near the floor are near ambient. Gas temperatures in 

excess of 600 °C (1110 °F) can be seen near the top of the kitchen doorway and at the top 

of the kitchen window. 

Figure 19 shows the same thermal planes, 55 s later at 540 s of the simulation. By this 

time, gases in excess of 600 °C (1110 °F) had spread across both the dining room and the 

living room, potentially igniting the combustible surfaces in the top portion of these rooms. 

Other gases, hotter than the ignition temperature of wood, are shown leaving the kitchen 

window and spreading up the outside of the house. This rapid change is consistent with a 

flashover occurring in the kitchen. 
10

Figure 20 displays the plane of temperatures aligned with the center of the stairs, 0.4 m 

(1.3 ft) into the house from the shared interior wall. Approximately 600 s or 10 min into 

the simulation, gases in excess of 600 °C (1110 °F) have filled the open stairwell. 

7.2.1. Flame Sheet Fire Simulation 

Figures 21 through 24 show a series of views of the simulation that approximate the flame 

spread through the structure. The iso-surface simulation provides a three dimensional 

approximation of the flame surface area where fuel, heat and oxygen are present such that 

flames may exist. The flames can be seen covering the top of the stove at approximately 

220 s or 8:28 AM, in figure 21. Approximately 4 minutes later, at 8:32 AM the fire has 

spread across the kitchen ceiling and has vented through the kitchen window as shown in 

figure 22. Figure 23 presents a side view of the house at approximately 8:33 AM. The 

flame front has extended through the dining room and into the living room. The final 

figure in the series, figure 24, shows the estimated flame sheet spreading up the stairway at 

600 s of simulation time or 8:34 AM. This series of figures is another demonstration of 

how rapidly the fire grew and quickly the flames spread through the house, trapping the 

firefighters. 

8. SUMMARY 

The NIST FDS computer simulation predicted fire conditions and events that correlate well 

with information from NIOSH and ATF. The model simulation was based on a fire that 

started on the kitchen stove. Smoke and hot gases from the fire began to spread through 

the house within seconds after ignition occurred. However, the FDS/Smokeview 

simulation of the flame front indicates that the fire itself did not spread beyond the kitchen 

until approximately 8 minutes after flaming ignition. 

The critical event in this fire was the on-set of conditions consistent with flashover in the 

kitchen. At this point, approximately 8:32 AM, this fire started a transition from a single 

room and contents fire with smoke throughout the structure, to a fire that involved the 

majority of the structure within approximately 60 s. The hot gas layer temperatures in the 

living room increased from approximately 200 °C to 300 °C (390 °F to 570 °F) to more 

than 600 °C (1110 °F) in less than a minute. The hot gases and flames continued to spread 

rapidly from the living room through the stairway to the second floor. This quick change in 

thermal conditions and flame spread through the duplex led to the 3 firefighters being 

trapped inside and succumbing to the effects of the fire environment. 
11

9. REFERENCES 

1. McGrattan, Kevin B., Baum, Howard R., Rehm, Ronald G., Hamins, Anthony, Forney, 

Glenn P., Fire Dynamics Simulator – Technical Reference Guide, National Institute of 

Standards and Technology, Gaithersburg, MD., NISTIR 6467, January 2000. 

2. McGrattan, Kevin B., Hamins, Anthony, and Stroup, David, Sprinkler, Smoke & Heat 

Vent, Draft Curtain Interaction – Large Scale Experiments and Model Development, 

National Institute of Standards and Technology, Gaithersburg, MD., NISTIR 6196-1, 

September 1998. 

3. McGrattan, Kevin B., Baum, Howard R., Rehm, Ronald G., Large Eddy Simulations of 

Smoke Movement, Fire Safety Journal, vol 30 (1998), p 161-178. 

4. McGrattan, Kevin B., Forney, Glenn P., Fire Dynamics Simulator – User’s Manual, 

National Institute of Standards and Technology, Gaithersburg, MD., NISTIR 6469, 

January 2000. 

5. Cholin, John, M., Wood and Wood-based Products, NFPA Fire Protection Handbook, 

18th ed Section 4, Chapter 3, National Fire Protection Association, Quincy MA, 1997. 

6. Stroup, D.W., DeLauter, L., Lee, J., and Roadarmel, G., Scotch Pine Christmas Tree 

Fire Tests, National Institute of Standards and Technology, Gaithersburg, MD., Report 

of Test FR 4010, December 1999. 

10. ACKNOWLEDGEMENTS 

The authors would like to thank Ms. Dawn Castillo, Mr. Richard Braddee and Mr. Thomas 

Mezzanotte of the NIOSH Fire Fighter Fatality Investigation and Prevention Program for 

their support of this research. The authors extend their appreciation to Special Agent 

Christopher Van Vleet and Andrew Cox of the Bureau of Alcohol, Tobacco and Firearms 

for their thorough documentation of the structure involved in this fire incident. Finally we 

would like to thank Dr. Kevin McGrattan for his continued development of the NIST Fire 

Dynamics Simulator Model. 
12

Figure 1. Front of structure. Duplex on right was the unit of fire origin. 

Figure 2. Back of structure. 
13

living room

dining room

closet bathroom

kitchen

porch

table

cabinets

waste can

chair chair sofa

stairs up

to second floor

first floor hall

4.20 m 4.20 m

3.80 m

6.93 m 3.99 m

table

1.80 m

1.80 m

4.00 m

Stove

Christmas

tree

Figure 3. Plan view of 1st Floor. Ceiling height of 1st floor 2.8 m, except for kitchen 

area, 2.4 m. 
14

front bedroom

middle bedroom

rear bedroom

bathroom

second floor hall

stairs down

to first floor

4.20m 4.20m

3.99m

porch roof

1.80 m

1.80 m

Figure 4. Plan view of 2nd Floor. Ceiling height 2.4 m. 
15

Figure 5. Results of fire extension from kitchen window up to rear bedroom. 

Figure 6. Inside view of kitchen, area of origin. 
16

Figure 7. Dining Room with table and chairs. 

Figure 8. Living room with sofa from front hall doorway. 
17

 

Figure 9. 1st floor hall with doorway to living room on left & front doorway on right. 

Figure 10. Stairway and 1st floor hall from front doorway. 
18

Figure 11. Second floor landing and stairwell looking toward front of structure. 

Figure 12. Rear bedroom above kitchen. 
19

Figure 13. Right front of duplex. Front bedroom window shown with lower portion 

open. Front door shown closed. The outer box frame represents the boundary of 

volume modeled. 

Figure 14. Yard side of duplex. Outer wall removed to show living room and dining 

room on the first floor and front and middle bedrooms on the second floor. 
20

Figure 15. Rear of duplex. The kitchen, with stove and cabinets, and a bathroom are 

shown on the 1st floor, the rear bedroom, above the kitchen, and a bathroom are on 

the 2nd floor. 

Figure 16. Shared side of duplex. The rear of the duplex is on the left of the figure. 

From the left, a bathroom, the kitchen, a closet under the stairs, the stairway and 

lower hall can be seen on the 1st floor. Also from the left, a bathroom, upper hall and 

front bedroom can be seen on the 2nd floor. 
21

Figure 17. Example of 3 dimensional grid arrangement. 

Figure 18. Thermal conditions at approximately 8:32 AM (491 s into simulation). 
22

Figure 19. Thermal conditions at approximately 8:33 AM (524 s into simulation). 

Figure 20. Thermal conditions at approximately 8:34 AM (605 s into simulation). 
23

Figure 21. Estimated flame boundary covering stove top at approximately 8:28 AM. 

Figure 22. Estimated flame boundary extending across kitchen ceiling and venting 

out of upper portion of kitchen window at approximately 8:32 AM. 
24

Figure 23. Estimated flame boundary spreading through the dining room and into 

the living room at approximately 8:33 AM. Flames continue to spread up the outside 

of the kitchen. 

Figure 24. Estimated flame boundary spreading through the dining room and into 

the living room at approximately 8:34 AM.