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Fire-fighting and Bio-Based Materials
Guidance on Fire-fighting and Bio-Based Materials
COST Action FP 1404
“Fire Safe Use of Bio-Based Building Products”
N225‐07
This publication is the result of work carried out within COST Action FP1404 “Fire Safe Use of Bio‐
Based Building Products”, supported by COST (European Cooperation in Science and Technology).
COST is a funding agency for research and innovation networks. The Actions help connect research
initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers.
This boosts their research career and innovation. More information available at www.cost.eu.
This guidance document may be cited as:
Smolka, J, Kempna, K. et al. Guidance on Fire-fighting and Bio-Based Materials, COST Action FP1404, Zürich, Switzerland, 2018.
DOI 10.3929/ethz‐b‐000319565p
Version 1 (2018)
Updates and corrections: http://www.costfp1404.ethz.ch/publications.
This publication was created in WG3 and can be considered as state of the art document. The
information in the book was carefully selected by experts from general technical knowledge,
standards, most recent research results and building practice. The author(s), the editor(s) and
publisher disclaim any liability in connection with the use of this information.
Neither the COST Association nor any person acting on its behalf is responsible for the use of the
information contained in this publication. The COST Association is not responsible for the external
websites or other references referred to in this publication.
No permission to reproduce or utilise the contents of this publication by any means is necessary,
other than in case of images, diagrams or other material from the copyright holders. In such cases,
permission of the copyright holder(s) is required.
Team of Authors:
Jan Smolka1, Kamila Kempná2, Markéta Hošťálková3, Denisa Bergerová4, Tomaž Hozjan5, Dionysis Kolaitis 6, Elzbieta Lukaszewska8, Anne Elise Steen-Hansen8
1,2,3,4 Lumírova 13, Ostrava, Faculty of Safety Engineering, VŠB-TUO, Czech Republic, [email protected] 5 Jamova 2, 1000 Ljubljana, University of Ljubljana, Slovenia 6 Heeron Polytechnikou 9, Athens, National Technical University of Athens, Greece 7 Stadsgården 10, 9tr, Stockholm, Byggnadstekniska Byrån, Sweden 8 Tillerbruvegen 202, Trondheim, RISE Fire Research Norway, Norway
Foreword
This document is focused on problematic of firefighting in bio‐based buildings. It collects
experience, information, knowledge and results from experiments which can be seen as helpful for
firefighters to better understand structural fires with bio‐based materials and as well as for incident
commanders with decision makings. As every fire is different, information might not be applicable
for all cases and every decision depends on specific conditions various than described in this
document.
Acknowledgments
Heartfelt thanks to Stefan Svensson from Myndigheten för samhällsskydd och beredskap, Lars
Brodin and Ville Bexander from Brandskyddsföreningen Sverige, Byggnadstekniska Byrån, Barry
Levis, Daniel Olsson from Storstockholms brandförsvar, Vincenzo Puccia from Corpo Nazionale dei
Vigili del Fuoco, Sami Kerman from Suomen Palopäällystöliitto, Andrew Macilwraith from Cork
County Council, Peter McBride from City of Ottawa and Francisco Javier Elorza from Provincial
Council of Bizkaia for collaboration help, collaboration, consultancy and providing valuable
information.
The authors gratefully acknowledge the European COST Action FP1404 on Fire safe use of bio‐based
building products.
Nomenclature ............................................................................................................................ 1
1 Introduction ....................................................................................................................... 2
2 Recommended Literature ................................................................................................... 2
3 “Green” Buildings ............................................................................................................... 3
4 Fire Development ............................................................................................................... 5
4.1 Timeline of fire Development ............................................................................................ 5
4.2 Fire Behaviour Changes ...................................................................................................... 7
4.3 Fire development and response of structure ..................................................................... 8
5 Properties of Wood in Fire ................................................................................................. 9
5.1 Pyrolysis and Combustion .................................................................................................. 9
5.2 Fire Spreading and Development ..................................................................................... 10
6 Specific fire hazards related to bio‐based buildings .......................................................... 13
6.1 Modern vs Legacy Buildings ............................................................................................. 13
6.2 Light‐weight Structures .................................................................................................... 14
6.3 Heavy‐weight Structures .................................................................................................. 16
6.3.1 Glue Laminated Timber ............................................................................................ 16
6.3.2 Cross Laminated Timber ........................................................................................... 16
6.4 Building Envelope ............................................................................................................. 18
6.5 Green Roofs and Facades ................................................................................................. 20
6.6 Void Spaces ...................................................................................................................... 21
6.7 High‐rise Buildings ............................................................................................................ 23
6.8 Airflow Impact on Fire Development ............................................................................... 26
7 Extinguishing and Bio‐Based Materials ............................................................................. 27
7.1 Extinguishing Agents ........................................................................................................ 27
7.1.1 Water ........................................................................................................................ 28
7.2 Additional Hazards in Buildings in general ....................................................................... 35
8 Case Studies ..................................................................................................................... 36
8.1 Fire Safety on Construction ‐ Hotel Spindleruv Mlyn, Krkonose, Czech Republic ............ 36
8.2 Historical Buildings ‐ Royal Institute of Art, Stockholm (Sweden) ................................... 38
9 Conclusion ....................................................................................................................... 42
References ............................................................................................................................... 43
List of Figures ........................................................................................................................... 46
List of Tables ............................................................................................................................ 48
1
Nomenclature
CLT – Cross Laminated Timber
CCCS – Cobra Cold Cut System
HRR – Heat Release Rate
2
1 Introduction
Buildings as environment where people spend their lives are among other designed to withstand
certain time of a fire, allows safe evacuation and conditions for fire‐fighting. They should be design
in a way to prevent fire spread between fire compartments and to other neighbouring buildings.
Modern building industry is significant by its intent to build sustainable, environmentally friendly
and safe structures using both, traditional and new materials. In this regard, the use of bio‐based
materials has expanded widely in recent years and fire‐fighters should consider several aspects and
risks related to combustible material and modern technologies.
The document offers a brief view to risks related to safe rescue and extinguishing actions for fire‐
fighters and aspects to be considered for fire engineers. The survey was carried out in 3 rounds with
goal to gain information and experience from fire‐fighters across Europe. Surveys included
questions about procedures of fire‐fighting for case of bio‐based buildings, fire safety limitation in
a country, personal experience, extinguishing agents mostly used for fighting fires, equipment etc.
In the first round of survey, responses from Italy, Finland, Sweden, Canada, Spain and Estonia were
gained. Table 1 describes availability of specific guidelines for fire‐fighting in timber or bio‐based
buildings for particular countries. As described, most of the countries do not have a guideline for
fire‐fighting in considered type of buildings.
Table 1. European countries and Canada – guidelines for fighting fires
Country Italy Finland Ireland Sweden Canada Spain Estonia German Czech
Republic
Guidelines for fire‐fighting
timber buildings Yes* No No No
Under review
No No Yes No
*http://www.ivalsa.cnr.it/fileadmin/ivalsa/files/documenti/laboratori/Relazione.settembre.2011.pdf
The survey is further used to analyse leak of knowledge. Moreover, some interesting points from
analysis are highlighted in chapters.
2 Recommended Literature
Topic of fire and firefighting of bio‐based buildings is wide and complicated. Therefore, it is not
intent include in this guideline all explanation about fire phenomena nor full description of fire
development problematic, spreading and fire dynamics. For deeper understanding of problematic
described in this document, it is recommended to use following literature. The document will
describe and mention specific protentional hazards and risk related to fires in buildings made of
bio‐based materials. Many hazards will be briefly described with link to documents where one can
find deeper description oversizing purpose of this document.
Following documents content basic important knowledge about enclosure fires and fire ventilation
for purposes of fire‐fighters.
3
Bengtsson, L. and Hardestam, P. (2005). Enclosure fires. Karlstad: Swedish Rescue Services Agency
[1]
This document describes fire dynamic for fire‐fighters purposes including fire spreading, fire
development, scenarios and intensive fire development (flashover, backdraft, etc.).
Svensson, S. (2006). Brandgasventilation. Karlstad: Räddningsverket. [2]
Author included the most important information about tactical ventilation with dependencies on
local conditions, ventilation conditions and impact on fire development in this document.
Additional recommended literature is placed in every chapter, where deeper information will be
provided for better understanding.
3 “Green” Bui ldings
In past years development and construction of “Green” Buildings is more and more popular. New
bio‐based materials and green technologies – have advanced to the extended they are applicable
for this type of buildings to increase energy efficiency.
Figure 1 – Example of ‘’green’’ building ‐ Sekisui House [3]
The approach to build “Green“ buildings is focused on minimizing
a building’s impact on environment, its occupants and the community
by “green“ design, construction, and demolish processes. One example of possible associations of
technologies and bio‐based material is building on Figure 1. [7].
Table 2 describes possible and common components applicable to ‘’green’’ buildings. [7]
Common Bio‐Based Materials:
‐ Wood ‐ Wood fibre
plates ‐ Bamboo ‐ Straw ‐ Linoleum ‐ Sheep wool ‐ Paper flake
panels ‐ Seagrass ‐ Cork ‐ Coconut ‐ Lignin
4
Some of green building materials can support rapid flame spread and fire spread quickly – some of
these materials can be straw, seagrass, untreated cellulosic insulation or lightweight building
elements. Some of these materials can even minimize the results of an accelerant‐based fire
growth [7].
Table 2 – Summary of elements and aspects characterizing “green” buildings in order to minimize building
effect on environment and people [7].
Structural Material and Systems Interior Space Attributes Alternative Energy Systems
‐ Lightweight engineered lumber ‐ Tighter construction ‐ PV roof panels
‐ Lightweight concrete ‐ Higher insulation values ‐ Oil‐filled PV panels
‐ Fibre reinforced polymer (FRP) elements ‐ More enclosed spaces ‐ Wind turbines
‐ Plastic lumber ‐ More open space (horizontal) ‐ Hydrogen fuel cells
‐ Bio‐polymer lumber ‐ More open space (vertical) ‐ Battery storage systems
‐ Bamboo ‐ Interior vegetation ‐ Cogeneration systems
‐ Phase‐change materials ‐ Skylights ‐ Wood pellet systems
‐ Nano materials ‐ Solar tubes ‐ Electric vehicle charging station
‐ Extended solar roof panels ‐ Increased acoustic insulation ‐ Tankless water heaters
Exterior Materials and Systems Interior Materials and
Finishes Site Issues
‐ Structural integrated panel (SIP) ‐ FRP walls / finishes ‐ Permeable concrete systems
‐ Exterior insulation & finish (EFIS) ‐ Bio‐polymer wall / finishes ‐ Permeable asphalt paving
‐ Rigid foam insulation ‐ Bamboo walls / finishes ‐ Use of pavers
‐ Spray‐applied foam insulation ‐ Wood panel walls / finishes ‐ Extent (area) of lawn
‐ Foil insulation systems ‐ Bio‐filtration walls ‐ Water catchment / features
‐ High‐performance glazing ‐ Glass walls ‐ Vegetation for shading
‐ Low‐emissivity & reflective coating ‐ FRP flooring ‐ Building orientation
‐ Double‐skin façade / cavity walls ‐ Bio‐polymer flooring ‐ Increased building density
‐ Bamboo, other cellulosic ‐ Bamboo flooring ‐ Localized energy production
‐ Bio‐polymers, FRPs Building Systems & Issues ‐ Localized water treatment
‐ Vegetative roof systems ‐ Natural ventilation ‐ Localized waste treatment
‐ PVC rainwater catchment ‐ High volume low speed fans ‐ Reduced water supply
‐ Exterior cable / cable trays ‐ Refrigerant materials ‐ Hydrogen infrastructure
Façade Attributes ‐ Grey‐water for suppression ‐ Community charging stations
‐ Area of glazing ‐ Rain‐water for suppression ‐ Area of combustible material ‐ On‐site water treatment ‐ Awnings ‐ On‐site waste treatment ‐ Exterior vegetative covering ‐ On‐site cogeneration ‐ High reliance on natural lighting
‐ PV exit lighting ‐ Reduced water suppression systems
5
Combination of properties mentioned above can represent specific potential risks and hazards as
described in Table 3.
Table 3 – Potential Risks connected with „Green“ Buildings [7]
Potential Risk and Hazards
Potential ignition hazard
Potential shock hazard
Potential explosion hazard
Potential toxicity hazard
Readily ignitable
Burns readily once ignited
Contribution to fuel / increased heat release rate (HRR)
Burning characteristics affected by building material
Fast(er) fire growth rate
Significant smoke production/hazard
Potential for shorter time to failure
Failure affects burning characteristics
Failure presents smoke spread concern
Failure presents flame spread concern
Material presents flame spread concern
May impact smoke/heat venting
May impact occupant evacuation
May impact fire‐fighter (FF) water availability
May impact suppression effectiveness
May impact fire apparatus access
May impact fire‐fighter (FF) access and operations
May impact containment of runoff
4 Fire Development
The magnitude of impact on structure depends on time of free fire development before
intervention. The impact and sensitivity of structure depends on dimensions and flammability of
structure, fire load and its fire properties.
4.1 Timel ine of f i re Development
The most important critical factor in fire development for intervention is time. Importance of time
and timeline with key moments from ignition to start of extinguishing is described in Figure 2.
6
Figure 2. Time‐line of fire development before fire intervention [21]
t1 – fire ignition [1 – 30 min]; t2 – fire development until start of extinguishing procedures [1 – 30 min]; t3 ‐
time of fire spreading from fire extinguishing procedures to fire localization [1 – 5 min];
The time of fire development tdev before arriving of fire‐fighters can be simplified and estimated
with Equation 1 [21].
t t t t t t (1)
Time of fire observation (tob) can range from 1 to 15 minutes or more with respect to installation of
fire detection or extinguishing systems. Time of calling to operation centre (tcall) from ignition if the
detection is connected to operational centre can vary from 1 minute up to tens of minutes when
the detection is not connected. Then, time when fire and rescue service by operational centre (tinfo)
is counted (cca. 1‐5 minutes) and followingly response time of fire‐fighters (tt) which can range from
1 to 10 minutes, depends on type of a fire station. Just before intervention starts, arriving time of
first fire‐fighters on place of fire (tpr) is expressed by Equation 2 [21].
t60 . L
v (2)
Where (L) is distance between burning building and fire station in kilometres and (vj) is traveling
speed of fire‐fighting vehicle to the place of fire. [21]
Based on described timeline, minimal time for fire‐fighters’ arrival can be estimated as ca. 7 minutes
minimally. This time deals with ideal conditions as arriving time from ignition is usually much longer
and could raise even more than 45 minutes, especially in areas with low density population[21].
Time of fire development impacts to survivability
‐ Likelihood of rescue success
‐ Higher possibility of structural collapse
‐ Higher risk for fire‐fighters
‐ Likelihood to survive post‐flashover = near zero
7
Survey of Fire‐Fighters experiences
Regarding timeline of fire development, survey about fighting fire has been conducted. During the
second round of the survey fire‐fighters were asked about their experience with fire‐fighting in
timber structures. Questions oriented to single significant fires in timber buildings were focused on
the cause of fire, phase of fire when fire‐fighters arrived on place of fire, and when the extinguishing
procedures were started. Additionally, they were asked about information whereas sprinkler
system in a fire building was applied and additional information about the individual fire attack.
Last but not least, couple of questions was about time needed for localization and extinguishing the
fire as presented in Table 4. Phase of fire represents phase, when fire‐fighters reach to incident.
Table 4. Results of Survey.
Country Origin of Fire Phase of Fire Application of
Sprinkler Systems Time of
Extinguishing
England Arson IV. No >5 h
Belgium Negligence III. ‐ ‐
France Other II. Sprinklers, water
mist <1 h
Portugal Technical Failure
IV. ‐ ‐
Slovenia Other III. No 1‐2 h
Sweden Technical Failure
IV. No 4‐5 h
4.2 Fire Behaviour Changes
It is critical for every intervention unit to know as much about estimating fire development as
possible. Therefore, main fire behaviour parameters, structure reaction to fire and technical fire‐
fighting aspects in bio‐based buildings are given here. Observations are based on survey results and
compared to knowledge and experience from traditional (old) buildings. Changes in applied
materials in combination of using flammable material with synthetic materials in building as fire
load can cause:
‐ Shorter time to flashover
‐ Charring and consequently cracking of wood allow smoke and heat to spread in structures
‐ Increased possibility of intensive fire development – backdraft, flashover
‐ Hidden fire spread in structures (walls, cladding, attics, etc.)
‐ Fire reignition after extinguishing
‐ Fire spreading in void spaces and attics – higher possibility of backdraft occurrence
The application of flammable materials as structure can cause following structure reaction to fire:
‐ Cracking of structure allows smoke spreading
‐ Structure’ affectation by extinguishing (e.g. water)
‐ Premature collapse
‐ Chimneys can be cause of ignition
‐ Hydrophobic properties of fire insulation materials complicate fire extinguishing
8
‐ Late fire observation – development and spread of fire in structures
‐ Steel and glued elements can support spread of fire
Additional aspects increasing fire hazards and rapider fire development can cause following
technical aspects of structure:
‐ Increased fire hazard during construction and maintenance
‐ Sprinkler failure can cause serious damages – e.g. delay of water mist extinguishing
system can postpone flashover
‐ Presence of materials with higher flammability and hazardous materials can cause serious
damages on structure
‐ Wrong design or building procedures can cause serious damages and misfunction of fire
protection
4.3 Fire development and response of structure
Figure 3 describes fire development and flammable structural response – survivability / structural
strength decreasing during fire development. These parameters can be affected by fire load
(quantity, HRR, geometry, dispersion, etc.), structural properties (flammability, thickness, type of
structures, etc.) and application of fire suppression systems.
Figure 3 – Structural strength vs fire development and its intensity [26]
This diagram is very important especially for light‐weight constructions, which their fire resistance
is the most sensitive to fire.
Temperature
9
5 Properties of Wood in Fire
For building modern and „Green“ buildings,
different types of wood (timber, bamboo,
cork, coconut, etc.) and their substitutes
(linoleum, gypsum boards, paper flakes, etc.)
are used.
Wood as solid organic material behaves
differently than steel or bricks in a fire. As
surface temperature increases due to fire
exposure, flammable vapours are produced
and cause burning of wood on the surface. As
a result, char layer is formed on the external
surfaces as shows Figure 4.
With thicker char layer, insulation of the
remaining unburned wood is better and the
rate of flammable vapour production
decrease, thereby the charring process is
slowing. Knowledge about what is happening
with wood in conditions of fire can be crucial
in decision making on a fire scene.
5.1 Pyrolysis and Combustion
Preheating
While heating wood initially starts to dry. Up to certain conditions, the process is reversible.
However, evaporation of chemically bounded water occurs bellow 100°C and wood can start
shrinking, joints weaken, and process continue. Gases formed from temperature up to 200°C are
mainly water and thus non‐combustible. Based on recent research from Reszka and Yang [20], It is
known that pyrolysis (thermal decomposition) take place in temperature range of 225°C to 500°C.
Ignition
Gases above the surface created from preheated solid material can be ignited by an ignition source
or self‐ignited. Ignition starts with the process of pyrolysis and visual flames can be observed.
Mentioned phenomena begins in temperature range between 225°C ‐ 275°C.
Figure 4 – Process from raw wood, affected by
radiation heat to ash [4].
Various engineered wood and substitute materials with addons (glue, oils, retardants
etc.) can seriously affect fire properties of any material.
10
Radiant heat
For fire conditions it is important to estimate heat flux on surface exposed to radiation for
firefighters.
Critical radiant heat flux for pilot ignition is 12 kW/m2 [22] and 28 kW/m2 for spontaneous ignition
while critical surface temperature for the first case is 350°C [23] and for the second 600°C [23], both
for the conditions of radiant heating.
For example, for the UK, building separation distances are calculated on the basis that exterior wall
of one building must not be exposed to a heat flux more than 12 kW/m2 [24].
Interestingly, charred surface temperature of wood can reach 800°C.
Table 5 – Average temperature range for decomposition process for wood [6.7.8].
Temperature range Decomposition processes
>100°C ‐ The evaporation of chemically unbound water.
160‐200°C ‐ The three polymeric components of wood begin to decompose slowly. Gases formed at this stage are non‐combustible (mainly H2O).
200‐225°C ‐ Wood pyrolysis is still very slow, and most of The Gases produced are non‐combustible.
225‐275°C ‐ The main pyrolysis begins, and flaming combustion will occur with the aid of a pilot flame.
280‐500°C ‐ Gases produced are now volatile (CO, methane etc.) and smoke particles are visible. Char forms rapidly as the physical structure of wood breaks down.
>500°C ‐ Volatile production is complete. Char continues to smoulder and oxidise to form CO, CO2 and H2O.
5.2 Fire Spreading and Development
Physical and chemical properties of materials affecting the fire spreading and development of fire
include type of wood, density, moisture content, etc. The major properties of wooden products
that define fire properties are mainly: [1]
‐ Thermal inertia
‐ Surface orientation
‐ Surface geometry
‐ The surrounding environment
Surface Orientation
Different fire spreading, and development can occur when fire spreads horizontally, compared to
fire spreading on vertical level. Figure 5 presents directions of fire spreading regarding the
orientation of surface. Since hot gases are lighter than cold air, fumes go up as well as flames. This
results in faster fire spread by preheating the wall in the vertical case. Thus, fire spread in horizontal
case is noticeably slower.[1]
11
Location of fire origin
Additional factor affecting fire spreading is angle of surrounding walls around the origin of fire and
flammability of the surface. How fast fire spreads indirectly depends on angle of surrounding walls.
That means the fire in corner will be the faster for fire spreading than for instance if fire origin is
surrounded by only one wall or when the fire origin is in the middle of a compartment.
The rate of flame spreading on surface depends on the surface heat inertia (kc). The higher value of heat inertia presents slower fire spreading on surface. Density of material indirectly impact speed
of flame spreading on surface which means flame on light materials will spread faster than on heavy
surfaces.[1]
Figure 5 – Vertical vs horizontal fire spreading on burning surface. [25]
Figure 6 – Fire and smoke development with fire origin in a corner or
on a single wall [1].
Figure 7 – Difference of fire spreading
between heavy‐weight and light‐weight
material [1].
12
Combination of fire spreading on vertical and horizontal way
The fire in compartment includes flame spreading in vertical and horizontal way. Figure 5 and Figure
8 describe the fire spreading in compartment with flammable structures. [1]
Surrounding environment
When the fire is developed in compartment, ambient temperature increase, too. Surface of the
compartment is preheated. The preheated surface will ignite faster. Example of these
consequences is preheating ceiling by hot gases generated from local fire. When flames reach under
ceiling layer, the surface is easier ignitable. This scenario is described in Figure 8.[1]
Figure 8 – Combination of Fire Spreading and preheated
under ceiling layer buy fire fumes [25].
Recommended Literature
Enclosure Fires [1]
Fire Ventilation [2]
13
6 Specif ic f ire hazards related to bio‐based buildings
This chapter describes specific hazards of bio‐based structures including dangers of light‐weight
structures, heavy‐weight structures, attics and void spaces, tall buildings with flammable
structures, airflow impact, etc.
6.1 Modern vs Legacy Bui ldings
Various hazards exist for specific type of buildings. There are different hazards between old or
historical buildings and modern “Green” buildings as Table 6 shows.
Thus, firefighters need to understand the difference between fires in legacy and modern buildings
and accordingly change their firefighting techniques and tactics.
Table 6 ‐ Different hazard specific for legacy and modern buildings [55][56]
Legacy (old) buildings Modern buildings
Unknown materials
Unknown impact of fire on structure
Premature collapse
Unknown plan of building
Hidden fire spreading in unknown way
Retrofitting and changes of structure
unknown to fire‐fighters
Possible absence or misfunction of fire
protection
Void spaces and attics
‚‚Black Buildings‘‘ – illegally build houses
Buildings in Wildland Interface
Large open stairs
Limited compartmentation
Increasing synthetic materials contented
in compartment
Smart Technologies
- Energy‐saving technologies
- Photovoltaic technologies
- Electric vehicles
- Energy storages
- Internet of Things
Larger footprint
Complicated and sophisticated foot print
Void spaces and attics
Flammable external cladding
Increasing number of stories
Open floor plan
14
6.2 Light‐weight Structures
Light‐weight structures belongs to the most common bio‐
based structures for its price, access to material, speed of
construction, variability and many other benefits. It is
estimated that this type of construction presents almost 50%
of accommodation buildings in the USA.
However, from firefighting point of view, they need to pay
attention to this type of structures. Especially, to related risk
and hazards for fire fire‐fighters.
The Fire Protection Association in the UK together with RISC
Authority published a document [26] with comparison of
hazards of light wood frame constructions (Figure 9) in the
UK and USA in 2011. Based on that:
‐ 72% ‐ of fire‐related deaths occur in homes in the
UK,
‐ 83% ‐ of fire‐related deaths occur in homes in the
USA.
More than half of these fires and fatalities occurred in
unprotected wooden frame buildings. It can be assumed that
fire prevention and fire‐fighting in these types of structures should be seriously considered based
on this research [26].
Figure 9 – Photos describing light‐weight construion and joints [15]
Signs of Structural Collapse
‐ Cracking
‐ Floors holding large volume
of water
‐ Walls / roof leaking water
‐ Movement in floor / roof
‐ Unusual noises
‐ Vertical / horizontal
structural members are out
of connections / joints
15
Specific hazards related with structural properties
‐ Hidden fire spread
‐ Rapid fire spread through structure
‐ Fire gases accumulation in structure
‐ Higher potential of Backdraft occurrence
‐ Potential roof and ceiling failure, resulting in full fire development in a floor below
‐ Premature structure collapse
‐ Increased fire load by synthetic e.g. foam insulation
Possibility of fire spreading in void spaces:
‐ Combustible vents and air shafts
‐ Anchor points in modular structures
‐ Polyurethane glued attaches gypsum walls and ceiling panels
‐ PVC plumbing fixtures
‐ Fire originating in the void spaces (e.g. cracked electric wires, loose wire connection, etc.)
Critical elements of light‐weight structures are joints connected with steel plates or adhesives
which may fail in fire and cause collapse of wall, floor, roof, etc. as Figure 10 shows.
Figure 10 – Photos presents impact of heat on joints and I‐beams during fire which cause collapse of
structure [26]
Recommended Literature
Fire Safety Challenges of Tall Buildings – NFPA[4]
Fire Safety Challenges of Green Buildings[7]
16
6.3 Heavy‐weight Structures
Heavy timber products are widely used for their greater strength and design flexibility. This
construction is usually built from rough large timbers beams and columns with timber section of
150 x 150 mm, sometimes with square elements larger than 150 mm. Heavy timbers’ advantages
include fire resistance, durability, sustainability and strength [29].
Material choices vary from glulam, PSLs, Laminated veneer lumber s or other engineered lumbers.
Glue Laminated Timber (glulam) and Cross Laminated Timber (CLT) due to their sustainability and,
strength and viable options commonly used for mass construction. Glulam allows flexibility of
different shapes and ability to change a space in open planes, whereas CLT offers a static system
for closed‐plan design.
6.3.1 Glue Laminated Timber
Glue laminated timber (glulam) is usually used as straight or curved for architectural and design
benefits enabling large section sizes and large spans. Glulam is also stronger than solid timber and
has high degree of dimensional stability for its structure as shown on Figure 11.
6.3.2 Cross Laminated Timber
Cross laminated timber (CLT) is manufactured in a similar way to glulam, except that layers of
timber are glued together with grain alternating at 90° angle for each layer as can be seen on Error!
Reference source not found.. These layers of wood improve CLT structural properties by
distributing strength of wood in both directions. This allows to be used to form complete floors,
walls and roofs [29].
Properties of heavy timber structures significantly affect the fire development. Typical behaviour
fire development is described in Chapter 4. However, fires with CLT or glulam are typical for
occurrence of the secondary flashover.
Figure 11 – Glue laminated timber with visible layers [28].
17
Among other wood related areas such as pyrolysis, charring, smouldering, fire dynamics or
structural response, there are two aspects closely linked to CLT or glulam. Delamination and
potential secondary flashover and change of fire development due to several layers glued together.
Fire development and delamination
Figure 12 demonstrates comparison of temperature curve of standard fire and average
temperature curve from a largescale experiment [30]. There are many aspects that affect all
phenomena’s, however, this experiment can serve well as an example of fire behaviour for such
situations.
Figure 12. Comparison graph between standard fire (dashed line) and average temperature during a
large fire test [30].
First stage from ignition to the first flashover is typical for preheating (this case lasts ap. an hour),
from the moment of the first flashover all contents in a room are burned and CLT/glulam panels
start to cool down. During the cooling, moment of delamination can occur. Then, the second,
already preheated layer will start burning. Namely, temperatures in a room are still high enough to
support burning of wood. As the fire develops further, temperatures and heat release rate rapidly
increase once more to conditions for the secondary flashover.
Delamination
As delamination it is understood falling off or loss‐of‐stickability of charred timber lamellae.
Currently there are several ongoing research projects on this topic around the world (Figure 13).
Factors as critical temperature, orientation, loading or grain direction are being researched for
better understanding.
18
As described in chapter 4.1, flashover is
recognized by rapid transition from a localized
fire to the involvement of all exposed flammable
materials. Generally, gas temperature ap. 600°C
and heat flux at floor level of 20 kW/m2 are
criteria for flashover. As demonstrated above,
these conditions can occur in compartments with
bio‐based structural elements repeatedly. These
phenomena are supported by continuous heating
of next layer under the fire surface. When burned
layer delaminates, the following layer continues
to burn. This effect needs to be considered for fires in these types of buildings.
6.4 Bui lding Envelope
As use of bio‐based materials increase, architects and designers have been using timber or other
material for building facades and insulation. Design and construction of a structure’s exterior can
be significantly challenging. Several aspects such as design and wind contribution to facade fires
should be considered to prevent fires as Figure 14 represents.
Figure 14 – A non‐traditional facade envelope a) before, b) during, and c) after a fire [32].
Figure 13 – Delamination of timber specimen
after experiment [31].
Recommended Literature
Fire Safety Challenges of Tall Wood[4][6]
19
Fire Spreading and Development of facade fires in bio‐based buildings. Possible ways of fire spread
on buildings where facades are made from bio‐based materials are shown in Figure 15:
‐ Heat radiation of adjacent building
‐ Flying hot and burning particles from adjacent building
‐ Fire outside a building immediately next to the external wall cladding
‐ Fire in a building in a room with an opening in the external wall
Figure 15 – Facade fire spreading [32].
The facade fire can be affected by wind, which can cause rapid fire development and spreading.
Factors affecting fire spreading on façade in the moment when fire is spread outside the
compartment are:
‐ Reaction to fire properties of the materials (combustible / non‐combustible material).
‐ The existence of cavities in a façade (burning of flammable insulation material due the
stack‐effect can cause five times faster fire spreading).
‐ Openings on a façade (doors, windows,) which allows fire spreading back into the
compartment in floors above the fire source.
Recommended Literature
Fire Hazards of Exterior Wall Assemblies Containing Combustible Components[5]
Composite materials can result in unusual fire damage.
20
6.5 Green Roofs and Facades
Main definition of green roof and facades is related to vegetation used in history as fire protection
cover roofs in Scandinavia with fire resistant soil.
Green roofs
Figure 16 describes composition of typical green roof – vegetation, substrate as growing medium,
insulation and drainage layer and waterproofing with roof deck. The growth media and plants add
weight to the final load and need to be considered in design process.
Figure 16 – Green roof assembly [10]
There are two types of green roofs – extensive and intensive. Intensive roofs are thick in
decimetres, heavy and with necessity to be irrigated (Figure 17). Extensive roofs are few
centimetres thick with moss‐sedum or sedum‐herb vegetation. This system does not need watering
for a long period. [9]
Figure 17 – Comparison of extensive (a) and intensive(b) green roofs [9]
21
Green walls
‐ Climbing plants – growing directly against the wall. Steel wires or mesh is used as
support. usually irrigated but can survive without irrigation if rooted into the ground.
‐ Hydroponic green walls – constructed from plastic, mesh, geotextiles, fabrics, mineral
wools or their combination. Plants grow without substrate/soil. System is irrigated.
‐ Modular green walls – made from modules filled growing medium and plants.
Fire hazard of green roofs and walls are:
‐ Green roofs and walls may constitute a general fire hazard.
‐ As long as the green roof or wall is kept moist (which is the normal case in order to keep
the roof alive) it is likely to be very resistant to ignition.
‐ If the green roof or wall dries out (such as might happen in a drought if no irrigation is
provided) then they might present more of a fire risk.
‐ Dry grass vegetation can present increased fire load.
6.6 Void Spaces
Building new structures increases application of new technologies and materials applicated for
buildings. One of the technologies is light‐weight construction system with void spaces. As void
spaces are understood:
‐ Attics and roof voids
‐ Void space in floors and walls
‐ Suspended ceilings
‐ Multiple ceilings
‐ Cavities in facades
‐ Engineering shafts
In case of fire these void spaces represent hazards for
fire‐fighters. Void spaces allow hidden fire spread in
structures which observation is difficult as well as its
extinguishing. Extinguishing in these structures
requires time dissembling for observation of fire
origin. Recommended equipment for extinguishing fire in void spaces are piercing nozzles (most
common FogNail, Cobra Cold Cut System, etc.), together with thermal vision for searching for
source of fire (example shown in Figure 18.).
Figure 18 ‐ Fire spreading through the
cavities, Luleå 2013 [34].
Recommended Literature
Fire Performance of Green Roofs and Walls[10]
22
Fires in void spaces are mainly ventilation controlled, which can present a significant threat of
extreme fire behaviour:
‐ Ventilation induced flashover
‐ Backdraft
‐ Smoke explosion
Extinguishing of structures with void spaces can present specific hazards for fire‐fighter and
complications in fire‐fighting such as: [34]
‐ Collapse of structures (walls, ceilings, etc.)
In old structures local collapse of part of structure is very common, in opposite to fire of
modern engineered light‐weight structure when falling of whole walls or ceilings occur.
‐ Falling fire‐fighters through the roof, floor, etc.
‐ Increased potential occurrence of extreme fire behaviour – flashover, backdraft, smoke‐
explosion.
‐ Stack‐effect can cause rapid fire spreading in structure.
‐ Possible fire spreading in direction from top to bottom.
Recommended Literature
Study of Residential Attic Fire Mitigation Tactics
Full scale fire tests with comparison of different extinguishing techniques to fires
developing inside cavities and Exterior Fire Spread Hazards on Fire Fighter Safety
Application of piercing nozzle can prevent intensive fire development such as flashover, ventilation induced flashover, etc.
23
6.7 High‐r ise Bui ldings
Application of new engineered wood materials
allows to build higher buildings. New timber
elements such as CLT currently allow to build
high‐rise buildings up to 18 storeys (e.g. Bergen
in Norway). [37]
The fire spreading in tall buildings can be split
on:
‐ Internal fire spreading (technical
shafts, cavities, etc.) ‐ Figure 20
‐ External fire spreading (facades,
ventilation shafts, etc.) ‐ Figure 24
Fire‐fighting in tall building with flammable structure can be more complex, hazardous and with
more possible complications such as fire spreading in cavities, premature collapse or secondary
crucial serious damages caused by extinguishing water which can affect structural stability.
Internal Fire Spreading External Fire Spreading
Figure 20 – Mechanical Shaft inside the building
[37]
Figure 21 – Façade fire [37]
Figure 19 ‐ Fighting fires of high‐risel buildings can
require fire platforms [36].
24
Possible differences in fire‐fighting consideration and fire behaviour between flammable and non‐
flammable structures are presented, as described in Table 7.
Table 7 – Comparison between flammable and non‐flammable structures[15][18]
Key tasks on arrival to place of fire in high‐rise buildings: [35]:
‐ Securing a water supply
‐ Setting in the dry rising main
‐ Identifying and securing the firefighting lift ‐ if one is available
‐ Establishing a bridgehead
Following phenomena affecting fire spreading in high‐rise buildings: [37][43]
‐ Positive stack‐effect
‐ Negative stack‐effect
‐ Blow‐torch effect
‐ External wind, depending on location as shown on Figure 22 and weather
‐ Pressure ventilation
Flammable Non‐Flammable
‐ Necessity to evacuate people from
structure as soon as possible.
‐ Extinguishing water can cause
premature collapse of building.
‐ Extinguishing can destroy building as
well as fire.
‐ Cracking of wood can cause hidden
fire and smoke spreading.
‐ Stack‐effect can cause fire spreading
in cavities.
‐ Increased fire‐load by structure which
can cause fire with higher intensity.
‐ Possibility to stay in building for
occupants.
‐ Evacuation routes works as fire‐fighting
routes.
‐ Building withstands extinguishing.
‐ In limited situation, occupants can stay in
structure until the fire is extinguished.
25
Figure 22 – Wind speed changes also with area where building is located.[57]
Considerations for fire‐fighting in high‐rise buildings:
‐ Limited use of elevators – especially for old buildings
o Complication with rescuing people
o Limited use of fire‐fighting platforms
‐ Limited use of wet and dry risings and pumps in building
‐ Reach of standard fire‐fighting hoses are limited by engine pump
‐ Higher risk of stack effect
‐ Air‐flow impact on fire development and spread
‐ Limited number of streams [43].
Recommended Literature
Fire Safety Challenges of Tall Wood[4]
Fighting Fires in High Rise Buildings [39]
Air & Smoke Movement in and around High‐Rise buildings (Air Tracks) [43]
26
6.8 Airf low Impact on Fire Development
Specific topic in area of bio‐based buildings are wind driven fires and related airflow impact on fire
development and spread. Wind driven fire can occur in situations with wind speed from 4 – 6 m/s
[23].
Following aspects are crucial for the wind driven fires observance:
‐ External wind
o Up‐Wind Direction of Vents
o Season
o Height of Storey
o Windy Area and common
wind direction (Wind rose
can be used as Figure 23
shows)
‐ Appliance of PPV
‐ Stack‐effect
‐ Combustion pressure
‐ Fire shafts
‐ Compartmentation [39]
Conditions affecting fire dynamics can have following impact. Information about fire‐fighting in this
situation comes from UL (USA), NIST (USA) and fire‐fighters from UK which shared their experiences
in frame of surveying in round 3.
Daniel Madrzykowski (NIST) and Stephen Kerber (UL) published many papers, presentations and
reports about wind‐driven fires, which are very beneficial for understanding of wind‐driven fires
and extinguishing procedures under these conditions – e.g. Fire‐fighting Tactics under Wind Driven
Conditions [41].
Impact of wind driven fires on fire spreading
With changing of wind direction, pressure impact changes as shown in Figure 24 and following
aspects and parameters can be easily changed:[43]
‐ Flow‐path changes
‐ Higher risk of occurrence an intensive fire development (flashover, backdraft, torch‐
effect)
‐ HRR increase
‐ Fire spread in void spaces
‐ Premature collapse of structure
Figure 23 – Wind rose [40]
27
Figure 24 – Pressure impact on structure caused by wind.[37]
7 Extinguishing and Bio‐Based Materials
As the construction and use of new materials develops, a compartment fire‐fighting techniques
and procedures are constantly being developed.
7.1 Extinguishing Agents
Nowadays, water is still one of the most common extinguishing agents. Some of the countries
additionally use Compressed Air Foam System (CAFS) for better wettability, cooling effect and
minimal water damages.
Table 8 shows countries where additional systems to fire‐fighting is used.
The conducted survey also focused on this topic. and fire‐fighters in Europe have been asked which
types of extinguishing agents and equipment is used for extinguishing of bio‐based structures.
Recommended Literature
Fire Fighting Tactics Under Wind Driven Conditions: Laboratory Experiments in
Houston[42]
Simulation of the Dynamics of a Wind‐Driven Fire in a Ranch‐Style House – Texas[44]
Air & Smoke Movement in and around High‐Rise buildings (Air Tracks) [43]
28
Table 8 describes that beside water the foam is additionally used for specific conditions in some
countries.
Table 8 ‐ Results of the Survey
Country Italy Finland Ireland Sweden Canada Spain Estonia England Czech
Republic
Agents Water Water Water Water Water / Foam
Water /
Foam Water Water
Water / Foam
7.1.1 Water
Water has much higher heat capacity than other extinguishing agents do. The accessibility is as well
much better.
7.1.1.1 Water Properties
The most significant property of water is heat capacity. Value for water is 4.184 J/kg°C and
represents the amount of heat required to raise the temperature of 1kg of water (ca. 1 litre) by one
degree of °C. This property is significant important for extinguishing and especially cooling hot gases
during fire‐fighting attack. Additional important factor of water is expansion ratio. The expansion
ratio of water at 100°C is ca 1:1700, which means that from 1 litter of liquid water 1700 litters of
steam is produced as represents Figure 25. [45]
Figure 25 – Expansion ration of water for 100°C [45].
Cooling effect of water in ceiling layer depends on efficiency of its evaporation. Smaller drops of
water can be better evaporated and better absorbed by the heat of hot gas layer. During fire‐
fighting attack, not all water is evaporated, and part of this water reaches lining of compartment.
The compartment extinguishing in hot gas layer is complex and requires deeper understanding of
physical laws. For efficient extinguishing special equipment, which allows application of water
under higher pressure and speed of droplets than standard nozzles. One of such special equipment
is piercing nozzle with pressurizing water mist (Fog Nail Nozzle, Cobra Cold Cut System,
etc.).[14][45]
1,7 m3
Expansion Ratio 1:1700 100 °C
1 litter of Water
29
Direct Attack
The most commonly used equipment in Europe is standard nozzle, for its variability and effectivity.
Table 9 demonstrates required amount of water for various compartments type.
Table 9 – Example of Water Supply Requirement of Specific Type of Compartment[21]
Compartment Amount of water per area in one minute (intensity)
[ l / m2 min]
Office 8.7
Accommodation 9.1
Attic 7.6
Garage 8.8
Storage 10.4
Example of Water Consumption in Extinguishing of Compartment Fire
Part I – Standard nozzle[21]
For example, extinguishing office compartment will be calculated required water supply for
extinguishing for 5 minutes.
Compartment dimension 5 x 6 m ‐> 30 m2
Maximal standard nozzle flow rate for Turbo‐Jet
Q = 400 l / min
Required flow rate for compartment
(Office)
Qef = 30 x 8.7 = 261 l / min (Required water supply from Table 9)
Required amount of water for 5 min of extinguishing
Qall = 5 x 261 = 1.305 litters
These results are only orientational and do not have to correspondent with real fire which can be affected by many factors – quantity, HRR, and type of fire load, geometry, orientation, stage of fire, etc.
Flow Rate Qmax = 400 l / min
30
While considering fire‐fighting in flammable structure, it should be respected and considered that
is necessary to extinguish fire, burning structure and additionally stop pyrolyzing processes of
flammable parts. It can require higher volume of water compared to usually considered in
extinguishing of non‐flammable structures.
Water Damages
Extinguishing of flammable structures, especially light‐weight structures can significantly affect load
bearing of structures. The application of high volume of water can have negative impact on
structures such as premature collapse of building, local collapse of structure (walls, roofs, etc.) and
secondary damages of floors below the fire as shown in Figure 27.
Figure 26 ‐ Fire in Luleå 2013 [46].
Small fires ‐ (1. and 2. stage of fire) ‐ minimum water damages
Flashover / After‐flashover stages – high volume of water – bigger water damages
Water damages can cause collapse or demolition of a building.
31
Non‐Direct Attack
Application of piercing nozzles prevents occurrence of backdraft and other dangerous fire
phenomena during entering the building. This extinguishing equipment allows to deliver
extinguishing agent into the compartment without entering. The water piercing nozzle is applied
through the wall, structures, etc. within small hole and followingly, water mist is delivered under
high pressure. The application of piercing nozzle should be combined with application of thermal
vision camera to find origin of fire.
The safer way of extinguishing enclosure fire is with non‐direct attack. This is allowed by special
equipment – piercing nozzles and application of pressurized water mist. The most common
equipment for this application is Fog Nail (Figure 27) and Cobra Cold Cut System (Figure 28). [14]
Figure 29 describes comparison between most common used equipment for fire‐fighting in
compartment fires. The comparison is between mentioned equipment CCS, FogNail and standard
nozzle. As it was described the efficiency of cooling effect of water mist depends on size of applied
water droplets in hot gas layer in relatively short time. Figure 29 shows that the most effective
cooling effect is reached with CCS, then with FogNail and as a last with standard nozzle. [14]
Mechanism of extinguishing by water mist: [14]
1) Heat extraction
a. Cooling of fire plume
b. Wetting/cooling of the fuel surface
2) Displacement
a. Displacement of oxygen
b. Dilution of fuel vapor
Application of piercing nozzles:[2]
‐ Void spaces
‐ Attics
‐ Compartment fires
‐ Difficult access structures – cavities, etc.
Figure 27 ‐ Piercing Nozzle Fog Nail [12] Figure 28 ‐ Cobra Cold Cut System [13]
32
Additionally, application of Piercing Nozzles and Cobra Cold Cut Systems have been observed.
Results of survey are presented in Table 10.
Table 10 Results of Survey of Extinguishing Equipment Application
Country Italy Finland Ireland Sweden
Equipment CCCS* Standard Equipment
Standard Equipment Standard
Equipment, CCCS*, piercing nozzles
Country Canada Spain Estonia Czech Republic
Equipment
Hand lines, master streams,
piercing applicators, rotary nozzles
Standard Fog Nozzle
No specific equipment. Ordinary fire hoses and nozzles, piercing nozzle, thermal camera (Flir),
motor saw etc.
Standard equipment, CCCS,
CAFS
FogNail
FogNail is cheaper form of application piercing nozzle using for extinguishing in compartments.
First, it is necessary to create hole in structure (window, door, frame, wall, etc.), then the process
can start. The flow‐rate of this nozzle is 70 l/min, which decreases secondary water damages.
FogNail has two different types of nozzle for various type of water mist delivering. Application of
piercing nozzle should be in closed compartment, where is prevented excess of oxygen and broken
structure. [1][12]
Figure 29 ‐ Comparison droplets sizes applicable by specific equipment – CCCS, piercing nozzle, standard
nozzle in distance [16][17].
33
Figure 30 ‐ Scheme of FogNail application [12].
Cobra Cold Cut System
CCCS is cutting extinguisher with ability to penetrate walls and outer layers and efficiently
extinguish fire by water mist delivered under high pressure. This water mist cools hot gases in
compartment and reduces potential risk of extreme fire behaviour. Nozzle flow rate is about 30‐60
l/min which decreases secondary loses from water damages and provides great opportunity to
extinguish fire from outside of the compartment without necessity to enter inside. Application of
nozzle is described on Figure32. [1]
Figure 31 – Application of CCCS for compartment fire‐fighting [55][56].
34
Comparison of Extinguishing Equipment
RISE published comparison results of specific fire‐fighting equipment used for extinguishing fires in
cavities and attics. In these experiments, extinguishing by standard nozzle, FogNail and CCCS
techniques are compared.
Experiments have been realized in full‐scale models of compartments with cavities and attics and
compared two different scenarios (Figure 32). Scenario A presented fire behind the outer wood
siding. Scenario B presented fire inside a cavity
behind a wooden wall connected to a cavity
above a false ceiling with possibility to spread in
loft.
presents resulted water consumption and
required time for extinguishing with different
extinguishing equipment in various scenarios.
Extinguishing in Scenario A shows possibility to
extinguish the object fast, with low water
consumption. Scenario B presents more
complicated scenario of fire spreading, especially
for finding origin of fire and its extinguishing.
There is rapid difference in water consumptions
when standard nozzle exceeds 1000 litters of water. In the opposite FogNail and CCCS show much
lower water consumption and time to extinguish the fire.[48]
Table 11 – Comparison of water consumption and time to extinguishing of different extinguishing
equipment [48]
Scenario A Scenario B
Extinguishing time
[mm:ss]
Water used [L]
Extinguishing time
[mm:ss]
Water used [L]
Cutting Extinguisher
02:32 Ca. 135 03:06 Ca. 150
Chain saw method 04:10 Ca. 220 18:14 > 1200
04:49 Ca. 450
FogNail ‐ ‐ 02:18 Ca. 400
Figure 32 ‐ Experimental compartment (1‐ Outer
wood siding, 2 ‐ Cavity, 3 ‐ Loft) [48].
Recommended Literature
A Review of Water Mist Fire Suppression Systems – Fundamental Studies[14]
35
7.2 Addit ional Hazards in Bui ldings in general
Some factors can generally change fire development and fire‐fighting procedures in buildings.
Between main additional factors can be personal aspects, technical aspects and fail of fire
protection systems.
Not properly working active fire protection systems
‐ Dry and wet risings and pumps
‐ Sprinkler systems and dry sprinkler systems
‐ Internal water hydrants
Figure 33 – Wet rise in building surrounded by
material [51]
Figure 34 – Non‐functional dry rising [50]
Technical aspect
Factor of human elements can cause serious
aftermaths. These factors can cause serious
damages on structures, malfunction of designed
fire protection, etc. Between main factors, the
following are listed:
‐ Illegal buildings improvements
‐ Danger fire load
‐ Overloaded fire load
‐ Insufficient construction
o Forbidden / fake materials
o Construction procedures not
followed
o Old structures
‐ Failure of fire protection systems
‐ Fake fire protection
Figure 35 – Danger fire load in
compartment increasing hazards of
fire [58]
36
Personal aspects
Personal aspects include dangerous behaviour of people, which can ignite fire directly or in non‐
direct way. This behaviour can include following:
‐ Fail in follow safety procedures
‐ Arson
‐ Health and mental disorder
‐ Drug addicted people
‐ Negligence
8 Case Studies
Authors of this document had possibility to visit some of the places of fire in buildings with bio‐
based materials. Two representative fires are highlighted below, one was a brand new, modern
building, the second one was more than 200 years old. From the case studies, important fire‐
fighting views can be taken and valuable lessons learned.
8.1 Fire Safety on Construct ion ‐ Hotel Spindleruv Mlyn, Krkonose, Czech
Republ ic
The pension was a 3‐storey building with 2 storeys above ground level and with 1 story under
ground level with dimensions 21.1 m x 9.4 m with aluminium roof. In underground level was a
garage, rest of the stories were used for accommodation. The building was built with I‐beams with
wood formwork, basalt thermal insulation and covered by OSB boards.
After long‐time of smouldering, the structure was interrupted and access to oxygen was created
resulting in rapid fire spread. Then the fire spread through entire envelope of the building to the
roof. The fire was observed in the moment when first flames appeared on the roof [52].
Figure 36 – Fire of a Hotel in Spindleruv Mlyn, Czech Republic [52].
37
The cause of fire was ignition of a part of structure in façade of the building by propane‐butane
burner during the hot works on hydro insulation. Mineral wool as thermal insulation supported
development of smouldering of flammable structure under the insulation. The smouldering was
developed and spread to envelope of the building. The smouldering would not be possible without
thermal insulation. The spread of smouldering was not immediately followed by generation of
flames, smell or producing smoke, which was the main reason for the late detection of the fire.
For verification of this scenario, investigators from fire brigade modelled possible fire scenario.
Results of the experiment are described in Table 12. [52]
Table 12 – Temperature development under the insulation [52]
Nr. Time after Ignition
[h]
Temperature in Insulation
[°C]
Temperature in beam [°C]
Movement of fire front [mm]
Picture Nr. Figure
37 [‐]
1 0.1 ‐ ‐ 10 ‐
2 0.29 ‐ ‐ 30 ‐
3 0.42 39 476 45 ‐
4 1.29 44 485 80 1
5 3.3 39 394 120 2
6 7.45 133 540 Ca. 250 3
During the experiments, thermal vision camera was used for recording heat spread and
accumulation under insulation, which is shown on Figure 37 [52].
1 2 3
Figure 37 – Experimental modelling to investigate possible causes of the fire. [52]
38
8.2 Historical Bui ldings ‐ Royal Inst itute of Art, Stockholm (Sweden)
The building known also as Båtsmanskasernen – barrack II is placed on Skepsholmen island,
centrally located in Stockholm. It was built during the years 1816 – 1819 and then housed 200
boatmen and 40 shipping reserves. The main rebuilding has been proceeded in 1870, 1892 and
1907. The building was rebuilt and open as Royal Art Academy in 1988 and worked as studios, art
workshops and dormitories for students and teachers until 2017. The building has six floors
including basement and attic. [53][54]
Figure 38 – Fire extinguishing from a platform after smoke explosion. Royal
Institute of Art, Stockholm [53][54].
Following fire intervention information, fire was split in two stages. The first fire was located in the
4th floor where clear origin of fire was later found. Fire spread in the first moments can be seen on
Figure 39 and Figure 40.
39
This scenario can be described as attic fire when fire was spreading from the fire room to the roof.
It propagated into ventilation shaft and through a small window located above the windows of the
first fire.
When fire moved from the first compartment to the attic, development of fire changed into
intensive fire development with possibility of backdraft or smoke‐explosion occurrence. The fire
was complicated because of structural material uncertainties and presence of unknown amount of
flammable materials used for painting. The fire spread and fire suppression are shown in Figure 40
and Figure 41.
Figure 39 – Demonstration of fire and flames spread out from a window on the 5th floor to a ventilation
window above. Then the fire spread into attic. Royal Institute of Art, Stockholm [53][54].
40
Figure 40 ‐ Extinguishing the attic fire [53][54]. Figure 41 ‐ Extinguishing from the roof [53][54].
The Figure 42 shows final state of building after the fire and fire‐fighting attack.
Figure 42 ‐Photo taken after the fire. Significant damages as destroyed roof and wet walls can be spot.
Royal Institute of Art, Stockholm [53][54].
Table 13 describes resources needed to extinguish this kind of fire. These resources are split on two
phased, first phase is focused on extinguishing the compartment fire and second phase describes
resources needed to extinguish spread fire in attic.
41
Table 13 – Used resources for fire‐fighting [53][54].
When considering intervention in buildings from bio‐based materials, problematic of fire‐fighting is
not only limited to fire‐fighting in modern timber structures according to prepared fire‐fighting
procedures and techniques. There are also old wooden or hybrid structures. First responders do
not often know exactly building material or actual use of a building and thus search for people,
rescuing procedures and saving property can be difficult. For the mentioned procedures, it is
important to know potential fire spread and how to lead and organize a fire attack. Effective fire
extinguishing equipment and procedures need to be chosen wisely, as it can have major impact on
intervention effectivity.
Resources
After 1st hour of fire attack After 3rd hour of fire attack
5 Fire‐trucks 8 Fire Trucks
1 High‐volume capacity water truck 1 High‐volume capacity water truck
2 Commanding vehicles 3 Commanding vehicles
3 Platforms
Total: 39 fire‐fighters Total: 63 fire‐fighters
42
9 Conclusion
Bio‐based buildings have been very popular in some regions. Nowadays, this type of buildings is
found in places where they were not previously seen. Usually large and tragic consequences of a
fire occur when there is no prepared fire‐fighting internal guideline or procedures for effective, safe
and fast intervention. Another problem can be found with increasing number of floors in bio‐based
buildings from the fire‐fighting point of view. In frame of the COST Action FP1404 project it was
possible to work on this problematic internationally, widely and deeply. It was found that fire‐
fighters mainly come to scene at the 3rd stage of fire when fire is already fully developed. That
requires higher attention on fire‐prevention and fire‐fighters should be educated more sufficiently
in order to be prepared for possible new dangerous situations. Also, often materials and fire design
plans of the buildings are not known which further complicates the intervention. As survey revealed
most commonly equipment used for fire‐fighting in bio‐based buildings varies at most between the
countries. All the aspects mentioned in this paper related to bio‐based buildings are highly
important for fire‐fighters as well as for fire engineers who design buildings in safe way also for the
first responders. It should be noted that flammable structure can largely affect development of:
‐ faster fire growth & time to flashover,
‐ increased production of volatiles and smoke
‐ increased severity of external flaming,
‐ increased total heat release rate,
‐ longer burning duration and
‐ possibility of secondary flashover.
43
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46
List of Figures
Figure 1 – Example of ‘’green’’ building ‐ Sekisui House [3] .............................................................. 3
Figure 2. Time‐line of fire development before fire intervention [21] ................................................ 6
Figure 3 – Structural strength vs fire development and its intensity [26] ......................................... 8
Figure 4 – Process from raw wood, affected by radiation heat to ash [4]. ........................................ 9
Figure 5 – Vertical vs horizontal fire spreading on burning surface. [25] ........................................ 11
Figure 6 – Fire and smoke development with fire origin in a corner or on a single wall [1]. .......... 11
Figure 7 – Difference of fire spreading between heavy‐weight and light‐weight material [1]. ...... 11
Figure 8 – Combination of Fire Spreading and preheated under ceiling layer buy fire fumes [25]. 12
Figure 9 – Photos describing light‐weight construion and joints [10] ............................................. 14
Figure 10 – Photos presents impact of heat on joints and I‐beams during fire which cause collapse
of structure ....................................................................................................................................... 15
Figure 11 – Glue laminated timber with visible layers [28]. ............................................................ 16
Figure 13. Comparison graph between standard fire (dashed line) and average temperature during
a large fire test [30]. ......................................................................................................................... 17
Figure 14 – Delamination of timber specimen after experiment [31]. ............................................ 18
Figure 15 – A non‐traditional facade envelope a) before, b) during, and c) after a fire [32]. ......... 18
Figure 16 – Facade fire spreading [16]. ............................................................................................ 19
Figure 17 – Green roof assembly [10] .............................................................................................. 20
Figure 18 – Comparison of extensive (a) and intensive(b) green roofs [9] ...................................... 20
Figure 19 ‐ Fire spreading through the cavities, Luleå 2013 [18]. .................................................... 21
Figure 20 ‐ Fighting fires of tall buildings can require fire platforms [36]. ..................................... 23
Figure 21 – Mechanical Shaft inside the building [37] ..................................................................... 23
Figure 22 – Façade fire [37] .............................................................................................................. 23
Figure 23 – Wind speed changes also with area where building is located [37]. ............................ 25
Figure 24 – Wind rose [40] ............................................................................................................... 26
Figure 25 – Pressure impact on structure caused by wind .[37] ...................................................... 27
Figure 26 – Expansion ration of water for 100°C [45]. ..................................................................... 28
Figure 27 ‐ Fire in Luleå 2013 [46]. ................................................................................................... 30
Figure 28 ‐ Piercing Nozzle Fog Nail [12] .......................................................................................... 31
47
Figure 29 ‐ Cobra Cold Cut System [13] ........................................................................................... 31
Figure 30 ‐ Comparison droplets sizes applicable by specific equipment – CCCS, piercing nozzle,
standard nozzle in distance [14][15]. ............................................................................................... 32
Figure 31 ‐ Scheme of FogNail application [47]. .............................................................................. 33
Figure 32 – Application of CCCS for compartment fire‐fighting [39][40]. ........................................ 33
Figure 33 ‐ Experimental compartment (1‐ Outer wood siding, 2 ‐ Cavity, 3 ‐ Loft) [48]. ............... 34
Figure 34 – Wet rise in building surrounded by material [49] ......................................................... 35
Figure 35 – Non‐functional dry rising [48] ....................................................................................... 35
Figure 36 – Danger fire load in compartment increasing hazards of fire [35] ................................. 35
Figure 37 – Fire of a Hotel in Spindleruv Mlyn, Czech Republic [52]. .............................................. 36
Figure 38 – Experimental modelling to investigate possible causes of the fire. [52] ...................... 37
Figure 39 – Fire extinguishing from a platform after smoke explosion. Royal Institute of Art,
Stockholm [53][54]. .......................................................................................................................... 38
Figure 40 – Demonstration of fire and flames spread out from a window on the 5th floor to a
ventilation window above. Then the fire spread into attic. Royal Institute of Art, Stockholm [53][54].
.......................................................................................................................................................... 39
Figure 41 ‐ Extinguishing the attic fire [53][54]. ............................................................................... 40
Figure 42 ‐ Extinguishing from the roof [53][54].............................................................................. 40
Figure 43 ‐Photo taken after the fire. Significant damages as destroyed roof and wet walls can be
spot. Royal Institute of Art, Stockholm [53][54]. ............................................................................. 40
48
List of Tables
Table 1. European countries and Canada – guidelines for fighting fires ............................................ 2
Table 2 – Summary of elements and aspects characterizing “green” buildings in order to minimize
building effect on environment and people.[7] ................................................................................. 4
Table 3 – Potential Risks connected with „Green“ Buildings [7] ....................................................... 5
Table 4. Results of Survey. ................................................................................................................. 7
Table 5 – Average temperature range for decomposition process for wood [6.7.8]. ..................... 10
Table 6 ‐ Different hazard specific for legacy and modern buildings [10][11] ................................. 13
In Table 7, possible differences in fire‐fighting consideration and fire behaviour between flammable
and non‐flammable structures are presented. Table 7 – Comparison between flammable and non‐
flammable structures[12][13] .......................................................................................................... 24
Table 8 ‐ Results of the Survey ......................................................................................................... 28
Table 9 – Example of Water Supply Requirement of Specific Type of Compartment[16] ............... 29
Table 10 Results of Survey of Extinguishing Equipment Application ............................................... 32
Table 11 – Comparison of water consumption and time to extinguishing of different extinguishing
equipment [48] ................................................................................................................................. 34
Table 12 – Temperature development under the insulation [52] ................................................... 37
Table 12 – Used resources for fire‐fighting [37][38]. ....................................................................... 41
49
www.cost.eu
Guidance on Fire-fighting and Bio-Based Materials
COST Action FP 1404
“Fire Safe Use of Bio-Based Building Products”
Document N225-07
COST Action FP1404
Chair of COST Action FP1404: Joachim Schmid
Vice Chair of the Action: Massimo Fragiacomo