Fires in wood waste storages cause financial losses, are difficult to extinguish, and emit large amounts of fire effluents. The mechanisms related to fires in wood chip piles are not well elucidated. To find suitable preventive measures for handling such fires in wood waste, a better understanding of the physical properties of wood waste is needed. The present study investigates how granularity affects mechanisms of smoldering fire and transition to flaming in wood chip piles. Eighteen experiments with samples inside a top-ventilated, vertical cylinder were conducted. Heating from underneath the cylinder induced auto-ignition and smoldering fire, and temperatures and mass loss of the sample were measured. The results showed that granularity significantly affects the smoldering fire dynamics. Material containing larger wood chips (length 4-100 mm) demonstrated more irregular temperature development, higher temperatures, faster combustion, and higher mass losses than material of smaller wood chips (length <4 mm). The larger wood chips also underwent transition to flaming fires. Flaming fires were not observed for small wood chips, which instead demonstrated prolonged and steady smoldering propagation. The differences are assumed to be partly due to the different bulk densities of the samples of large and small wood chips affecting the ventilation conditions. Increased knowledge about these combustion processes and transition to flaming is vital to develop risk-reducing measures when storing wood chips made from wood waste in piles.

This report is commissioned by the Norwegian Directorate for Civil Protection (DSB) and the Norwegian Building Authority (DiBK). RISE Fire Research has been commissioned to evaluate the fire in the multi-storey car park at Stavanger airport Sola on the 7th January 2020. The aim is to promote learning points for public benefit with regard to the extent of the fire, regulations, extinguishing efforts, structural design, effects on the environment and the role of electric vehicles in the fire development. Information has been collected via interviews, on-site inspection, contact with stakeholders, review of relevant regulations, documents and literature. Design of the building: Active, passive and organizational fire protection measures have been evaluated. In our opinion, the multi-storey car park should have been placed in Fire class 4 (“brannklasse 4”), since it was adjacent to important infrastructure for society. The fire design documentation for building stages B and C has shortcomings in terms of assessment of sectioning, installation of fire alarm or extinguishing systems, as well as assessment of the fire resistance of the loadbearing structure. There are a number of inconsistencies that indicate that the fire risk has not been fully mapped and assessed in connection with the preparation of the fire designs. Regulations: No deficiencies were found in the regulations relevant to this incident. Small adjustments in wording between different editions of regulations (e.g. guidance for technical regulations) can have a major impact on how the regulations should be interpreted. It is important that the authorities highlight such changes and that the fire consultant who develop a fire engineering concept avoid uncritical reuse of content from older fire concepts. Handling of the incident: How the fire service and other parties handled the incident during the emergency phase has been evaluated, and learning points have been identified for the following areas (details in section 7.3): The basis for creating national learning after major events, action plans, exercise and training, collaboration and common situational understanding, management tools, call-out, information sharing and initial situation report, immediate measures, the goal of the effort and tactical plan, organization of the site, communication and collaboration, logistics and depots, as well as handling uncertainties and follow-up. Electric vehicles: Water analyses of selected metals relevant for batteries in electric vehicles did not show any lithium, and only low concentrations of cobalt. This indicates that batteries in electric vehicles did not contribute to pollution of nearby water resources. Observations during the fire indicate that electric vehicles did not contribute to the fire development beyond what is expected from conventional vehicles. Further technical studies of the batteries from the burned electric and hybrid vehicles are necessary to evaluate whether batteries from electric vehicles were involved in the fire.

Environmental impact, extinguishing foam: During the incident, a lot of extinguishing foam was used, but this led to a limited environmental impact. The extinguishing foam was found not to add substantial amounts of PFAS during the extinguishing efforts. Analyses conducted by COWI still show PFAS content in all water samples, which is linked to previous emissions. Oxygen depletion as a result of release of extinguishing foam is considered to have led to local toxic effects on the aquatic environment, but not a general negative effect on the sea life in Solavika. There is a need for stronger awareness of, and focus on the use of, extinguishing foams and logging of the amount of foam used. Here one may learn from Sweden. Environmental impact, smoke: Smoke from the fire was mainly not driven in the direction of the terminal buildings, and during the first period only in the direction of areas with low population density. The fire smoke affected the evacuation of a nearby hotel. Eventually, the wind turned in the direction of areas with higher population density, and a population warning was sent out. Based on few health consultations (11 at the emergency room and 2 in hospital), as well as the municipality’s assessment of the incident, it is assumed that the fire smoke had limited health consequences for neighbours. The smoke content has not been analyzed. Finally; learning points from evaluation of the fire are relevant for many stakeholders, such as the fire service, authorities, construction design, for the owner and for research in the field.

This report is commissioned by the Norwegian Directorate for Civil Protection (DSB) and theNorwegian Building Authority (DiBK). RISE Fire Research has been commissioned to evaluatethe fire in the multi-storey car park at Stavanger airport Sola on the 7th January 2020. The aim isto promote learning points for public benefit with regard to the extent of the fire, regulations,extinguishing efforts, structural design, effects on the environment and the role of electric vehiclesin the fire development. Information has been collected via interviews, on-site inspection, contactwith stakeholders, review of relevant regulations, documents and literature.

Design of the building: Active, passive and organizational fire protection measures have beenevaluated. In our opinion, the multi-storey car park should have been placed in Fire class 4(“brannklasse 4”), since it was adjacent to important infrastructure for society. The fire designdocumentation for building stages B and C has shortcomings in terms of assessment of sectioning,installation of fire alarm or extinguishing systems, as well as assessment of the fire resistance ofthe loadbearing structure. There are a number of inconsistencies that indicate that the fire risk hasnot been fully mapped and assessed in connection with the preparation of the fire concepts.

Regulations: No deficiencies were found in the regulations relevant to this incident. Smalladjustments in wording between different editions of regulations (e.g. guidance for technicalregulations) can have a major impact on how the regulations should be interpreted. It is importantthat the authorities highlight such changes and that the fire consultant who develop a fireengineering concept avoid uncritical reuse of content from older fire concepts.

Handling of the incident: How the fire service and other parties handled the incident during theemergency phase has been evaluated, and learning points have been identified for the followingareas (details in section 7.3): The basis for creating national learning after major events, actionplans, exercise and training, collaboration and common situational understanding, managementtools, call-out, information sharing and initial situation report, immediate measures, the goal ofthe effort and tactical plan, organization of the site, communication and collaboration, logisticsand depots, as well as handling uncertainties and follow-up.

Electric vehicles: Water analyses of selected metals relevant for batteries in electric vehicles didnot show any lithium, and only low concentrations of cobalt. This indicates that batteries inelectric vehicles did not contribute to pollution of nearby water resources. Observations duringthe fire indicate that electric vehicles did not contribute to the fire development beyond what isexpected from conventional vehicles. Further technical studies of the batteries from the burnedelectric and hybrid vehicles are necessary to evaluate whether batteries from electric vehicleswere involved in the fire.

Environmental impact, extinguishing foam: During the incident, a lot of extinguishing foamwas used, but this led to a limited environmental impact. The extinguishing foam was found notto add substantial amounts of PFAS during the extinguishing efforts. Analyses conducted byCOWI still show PFAS content in all water samples, which is linked to previous emissions.Oxygen depletion as a result of release of extinguishing foam is considered to have led to local toxic effects on the aquatic environment, but not a general negative effect on the sea life inSolavika. There is a need for stronger awareness of, and focus on the use of, extinguishing foamsand logging of the amount of foam used. Here one may learn from Sweden.

Environmental impact, smoke: Smoke from the fire was mainly not driven in the direction ofthe terminal buildings, and during the first period only in the direction of areas with lowpopulation density. The fire smoke affected the evacuation of a nearby hotel. Eventually, the windturned in the direction of areas with higher population density, and a population warning was sentout. Based on few health consultations (11 at the emergency room and 2 in hospital), as well asthe municipality’s assessment of the incident, it is assumed that the fire smoke had limited healthconsequences for neighbours. The smoke content has not been analyzed.

Finally; learning points from evaluation of the fire are relevant for many stakeholders, such as thefire service, authorities, construction design, for the owner and for research in the field.

Investigation of fires are useful tools for gathering experience and knowledge of how and why fires occur and why they develop as they do. Several tools for accident investigation that also are applicable for analysis of fires are available. Data from fires is valuable for different branches of the fire safety science and are also used in revisions of fire regulations. This paper describes the concept of accident investigation with focus on learning and presents how investigation from fires has been used as a valuable tool in Norwegian fire safety management. Examples of how learnings have improved the residential fire safety level in Norway over the last decades are described. Three different analyses of fatal fires over four decades have given knowledge about how and why residential fires start, and how the victims could be characterized. The fire fatality rate in Norway has decreased by 50% from 1970 until 2014, one of the reasons for this is believed to be implementation of several targeted fire safety measures over the years. Through fire investigations combined with research, new trends in society and their possible implications on fire safety can be uncovered and lead to a more proactive fire safety management.

Fire safety in buildings used for play and recreational activity

This project has been carried out on behalf of the Norwegian Building Authority (DiBK) and the Norwegian Directorate for Civil Protection (DSB) as part of the research agreement between DSB and RISE Fire Research.

The aim of the project has been to determine whether activity centres (offering indoor activities for different age groups, e.g. indoor playgrounds, trampoline parks and gymnastics halls) are well equipped to reduce the risk of ignition, spread of fire, and smoke production, and for high heat release as well as to handle escape in case of fire. All with regard to the particular combination of the number and type of visitors, type of activity in the premises, as well as the large amount of combustible and potentially highly flammable furnishings present in the building.

In this report we have described fire engineering issues specifically related to the activity centres, partly based on a study of technical reports from the buildings’ planning phase and monitoring reports from the operational phase.

Our main findings are related to

• Lacking overall fire safety evaluation regarding the building and the safety plans of the responsible business owner with respect to:- The significance of the furnishing and use of material for personal safety.- Distribution of responsibility to evaluate the furnishing in a risk perspective.

• Ignition and early fire development:- There is not enough focus on ignition sources in the design and planning phase.- The fire performance of materials is not sufficiently taken into account during the design and planning phase and the requirements for documentation are insufficient and not relevant enough.

• Escape:- Children's behaviour during escape is not taken into account when planning.- The activity in activity centres is not taken into account during the planning phase.- The effect of the interior (both material properties, physical position in the room and geometry) on the escape routes and escape time is not taken into account when planning.- Deviations from the requirement for low-placed way guidance systems are made on an uncertain basis.

• Organizational measures:- Organizational measures are hardly mentioned in the fire concepts.- Deviations regarding organizational measures during the operational phase is the responsibility of business owners. This indicates uncertainty or lack of competence of regulations

Recently questions about whether spread of heat and smoke in ventilation ducts during a fire represent an increased risk for personal safety and loss of properties have been raised. The technical solutions currently used to fulfill the pre-accepted performance given in the guidelines to the building regulations with regard to fire protection of ventilation ducts are largely based on descriptions in SINTEF's Building Design Sheet 520.352 on fire- and smoke protection of ventilation systems, and in BV Netts Guide for fireproof ventilation, also known as the BVNett Guide. This topic was once again raised in connection with the revision of the 2017 edition of the building regulations, when it was pointed out in inquiry statements that the pre-accepted performances are insufficiently defined and that the solutions outlined in the Building Design Sheet and the BVNett Guide are not sufficiently documented.

In order to elucidate this topic and provide scientific documentation on the extent to which the spread of heat and smoke in ventilation ducts represents a risk to persons and properties, the BRAVENT project (Fire and smoke spread in ventilation ducts) was initiated.

The project investigates issues related to heat dissipation in ventilation ducts, clogging of filters in ventilation systems due to smoke, the effect of the seal-up strategy with respect to pressure build-up in the fire room and smoke spread through leakages in the construction.

The objective of the sub-task presented in this report was to:

Compile a theoretical basis for the experiments and analyzes to be carried out.

1. Map relevant regulations for fire protection of ventilation systems.

2. Map standards that are the basis for determining the fire resistance of components included in a ventilation system.

3. Map the state-of-the-art regarding a. the need to fire insulate ventilation ducts.

b. the need to install bypass channels to prevent the filter systems from being clogged by smoke particles.

c. the effect of installing fire dampers in all fire-partitions with respect to smoke spread.

d. how smoke can be spread via ventilation ducts and leaks in the building structure.

e. the pros and cons of seal-up and extraction strategies.

© RISE Research Institutes of Sweden

This is sub-report 1, which summarizes the relevant, fire-related theory and state-of-the-art in the focus area. The report serves as the theoretical basis for planning of experiments and for the other activities in the BRAVENT project.

This is sub-report 2 of the BRAVENT project (Fire and smoke distribution in ventilation ducts) which presents results from experiments where the risk of spreading fire and heat in ventilation ducts has been investigated. In the experiments, the effect of fire insulation on the duct, and mixing hot smoke with air at room temperature in the duct (as from adjacent rooms) has been investigated. The ventilation duct was connected to a furnace at one end and a fan at the other end. The furnace was heated to the desired temperature, and hot smoke was drawn through the duct at a certain velocity. Thermocouples measured the temperature both inside the duct (smoke gas temperatures) and on the duct’s external surface at different distances from the furnace.

External fire-fighting in Midtbykvartalet – A feasibility study

The property developer E. C. Dahls Eiendom (ECDE) plans a building complex in a quarter in the city centre in Trondheim, the "Midtbykvartalet". The building will be enclosed by existing building blocks which to varying degrees hinder the fire service's access and efforts. Also, since the new building is intended for residential purposes, it will be necessary to install windows in fire rated walls against adjacent building. These factors result in deviations from a number of performance requirements in the guidelines to the regulations on technical requirements for construction works and there is therefore a need to find alternative solutions. It must be documented that these alternative solutions have at least as good an effect on fire safety as pre-accepted solutions would have. A potential side-effect of new, alternative solutions is that these can also, to some extent, protect the existing wooden buildings in the quarter.

The aim of this report has been to identify the state-of-the-art within active fire protection measures for external fire-fighting and to obtain an overview of existing solutions and manufacturers and to carry out an assessment of the potential of these solutions.

Risk scenarios

An overview of existing buildings in the Midtbykvartalet is presented as well as an overall description of the plans for development. Based on this, several scenarios have been identified to reveal the potential fire-spread hazard between the existing buildings and the planned building. Furthermore, a qualitative risk assessment has been carried out.

A literature study describes the state-of-the-art in water-based extinguishing systems for outdoor use. It deals with fixed extinguishers (facade sprinklers, water curtains), dynamic extinguishers, foam extinguishers, fire gels, as well as with sprinkler systems' effect and reliability. Furthermore, existing solutions (e.g. facade sprinklers, water curtains, water cannons and water mist turbines) have been surveyed, existing documentation described and assessed regarding suitability for use in the Midtbykvartalet.

From the identified scenarios, it appears that fires in existing buildings are more likely to spread to the new building than a fire from the new building to existing buildings. The greatest danger to the new building will be if a fire spreads in existing buildings, up through the roof, through windows or along the facade to the roof. In many cases, the fire service will have good access with their ladder trucks etc. to perform extinguishing efforts, at least in the early phase of the fire. But the risk of rapid internal fire spread, which may include several of the older buildings, can create a challenging situation for the fire service and a risk for the new building. In case of fire spread to the new building, the fire department will, due to the position and height of the building, have difficulty with aerial rescue and evacuation from the new building's higher floors.

Concept for the Midtbykvartalet

A combination of a static and a dynamic extinguishing system will provide the best balance between system robustness, extinguishing effect and flexibility for the Midtbykvartalet. Facade sprinklers are considered the most suitable static system solution. Facade sprinklers will primarily cool the facade of the new building and absorb heat radiation from a potential fire in the existing buildings, but will not be suitable for extinguishing or actively fighting a fire within the existing buildings. The design and planning of facade sprinklers shall take the design of windows, balconies and roof terraces into account, which have been identified as vulnerable points in the firewalls.

Dynamic systems such as water cannons and water mist turbines can be used to cool facades and to actively fight a fire over relatively long distances. In addition, such systems can be established so that the fire service can take over control of the extinguishing system as needed. This property is important, because of the height of the new building and because of how it is surrounded by existing buildings.

Both water cannons and water mist turbines can be combined with an automatic control that allows you to fight a fire at an early stage, even before the arrival of the fire service, as long as early detection is achieved. A fire that spreads within the existing buildings will not be possible to extinguish with permanently installed dynamic systems. Therefore, the cooling and extinguishing effect of such systems must be evaluated based on the scenario of a large fire in the neighbouring building, which has not been done before.

The cooling and extinguishing effects for both systems are largely dependent on their control system. The control system must be capable of aiming the water cannon or the water mist turbine at the fire, if required compensating for wind effects and selecting an appropriate water jet mode. Therefore, in order to adapt the control system to the Midtbykvartalet, it is necessary to quantify the cooling and extinguishing effect of such a system in advance and with regard to a potentially large fire in the adjacent existing buildings.

Selected water mist turbines have the option of operating in a full jet mode, like a water cannon. Therefore, such systems are considered more flexible than water cannons. However, water mist turbines set large amounts of air in motion and generate turbulence that can affect the fire. It is therefore important to investigate if and in which cases this can aggravate the fire and have a negative effect on other areas in the quarter.