Data concerning smoke control from full-scale fire experiments conducted in the Runehamar Test Tunnel in Norway in 2021 are summarized and analyzed. The tests were carried out as a part of commercial testing program of high pressure water mist nozzles. These tests included two free- burn tests, and several tests with high pressure water mist based fire suppression systems but only the data prior to activation of the systems are of concern in this study. The data are compared with the established prediction model and demonstrate good consistency. Suggestion on future testing is also made.

Due to the complexity of the long-narrow tunnel structure and the frequent occurrence of tunnel fire accidents, tunnel fire safety has attracted extensive attention. Since fire-induced smoke causes a great threat to personnel safety, the related research achievements are summarized and compared to show an overview of the smoke diffusion and control in four typical tunnel structures, i.e. single-hole tunnels, single-branched tunnels, H-shaped tunnels and urban traffic link tunnels (UTLT). For the smoke movement characteristic, the maximum temperature rise, longitudinal temperature distribution and vertical smoke stratification are mainly studied. The smoke control involves longitudinal ventilation, natural ventilation and mechanical smoke extraction. Among them, the smoke backflow length, critical velocity and smoke exhaust efficiency need to be taken into major consideration for the personnel safety evacuation. Due to the multiple branches in UTLT, the smoke diffusion behavior and control strategies are much more complex, which is worthy of further discussion about the local resistance and airflow organization. Besides, fire safety encourages new challenges under the increasing use of new energy carriers, and related work needs to be conducted to investigate the fire and explosion risk in the tunnel. These findings and conclusions in this comprehensive review can support the tunnel fire accident investigation, and provide a reference for the intelligent design of emergency ventilation systems in tunnels

Wildland-urban-interface (WUI) fires are a global challenge, requiring mitigation to reduce impacts. Some measures apply globally, while others require local adaptation. Regions with limited wildfire experience, such as Norway, or with limited technical capacity, such as South Africa, need to develop proactive WUI preparedness for the population, firefighters and property owners. Recent events illustrate that Norway and South Africa face distinct circumstances that require adapted WUI strategies. For example, the 2017 Knysna fires in South Africa caused major loss of life and property, and post-event analyses showed that more resilient building design could have significantly reduced damage [1,2]. In Norway, the 2014 Flatanger winter wildfire demonstrated how unusual seasonal conditions and strong winds can lead to rapid WUI fire spread [3]. We mapped existing WUI guidelines worldwide available in English or Scandinavian, (see [4] for details); FireWise (USA) by the NFPA, focuses on protection of structures in the WUI from a community and individual perspective. FireSmart (Canada) is similar to FireWise and also includes flammability of plants. The NRC WUI guidelines(Canada) is a guideline concerning the risk, vulnerability, assessment, and mitigation of WUI fires, detailing risk, vulnerability, land management, access, egress, water and power supply, community planning, construction materials, emergency planning, and outreach. MSBs website (Sweden) shows steps to take for citizens to protect houses, and prevention of forest and vegetation fires for forest workers and owners. Locally developed South African guidelines implemented by private companies (e.g. Vulcan Risk Solutions) were also integrated. These guidelines found worldwide form the basis for the development of new, local guidelines for Norway and South Africa. In Norway, stakeholders evaluated the guidelines through workshops, surveys, and expert consultations. Local building conditions and regulations were also considered in the process. Insights from past fire events, fieldwork and laboratory experiments were also used to assess the relevance of international guidelines to Norway. This process was a part of TREEADS [5] and resulted in 5 main recommendations (Fig 1) [4]. Work is now underway to expand the guidelines for Norwegian communities and to develop the first WUI guidelines for South Africa, as part of a research project named WildfireSafe [6].

Wildland-urban-interface (WUI) fires are a global challenge, requiring mitigation to reduce impacts. Some measures apply globally, while others require local adaptation.

The production and usage of combustible thermal insulation like polyisocyanurate (PIR), wood fibre and cellulose in buildings are increasing. Traditionally, PIR has only been used in the ground and on roofs, in combination with non-combustible structures. During the last decade, the field of application for PIR has extended to walls, floors, and roofs, as well as to larger buildings. Woodfibre and cellulose insulation have been used in Norway since the early 1980s in combination with constructions of combustible materials, both as insulation of old constructions and as insulation in walls, roofs and floors in new buildings. During the last decade the area of use is also extended to larger buildings. Even if some fire testing is performed, there is a lack of knowledge about the fire behaviour of these combustible insulation materials and how theyaffect the fire development and spread, and the vulnerability to damages in the fire protectivecladding.The fire performance of these combustible thermal insulations has, therefore, been studied through fire experiments. Fire performances studied here are the temperature development in the material and the behaviour of the material when exposed to fire in terms of charring and general degradation. Three different fire test series have been conducted to study the performance of combustible insulation in timber frame assemblies with fire protective claddingsof gypsum boards or plywood boards. The insulation products tested are Kingspan Therma TW50 PIR, Hunton Nativo® Wood Fibre insulation batts, Hunton Nativo® Wood Fibre loose-fillinsulation, Ekovilla batt cellulose insulation and CBI Norge Isocell Evolution loose-fill cellulose insulation. For comparison, the non-combustible insulation products Glava Proff 34 batts (glass wool) and Rockwool Flexi A board (stone wool) were also tested. Two standardised test methods with additional measurements were used: EN 1364-1 for fire resistance of non-loadbearing walls and EN 13823 Single Burning Item (SBI) test for reaction to fire testing. In addition, a nonstandardised method was used to study both wall and roof together, as well as the intersection between them. In the non-standardised test and the fire resistance test, the temperature development in the furnace followed the standard temperature-time curve given in EN 1991-1-2, while in the SBI test, the applied fire source was as described in EN 13823. The temperature development in the constructions was measured with thermocouples, and the degradation of the insulation was observed visually and measured after the tests.The main goals, results and conclusions are:

(1) Fire and temperature development in combustible insulation productsThe goal was to study the fire and temperature development in combustible insulation products made of polyisocyanurate (PIR), wood fibre and cellulose when used in building constructions like walls, floors and roofs, and the effect of damages and penetrations from technical installations in the fire protective cladding. The results from fire experiments on specimens with PIR, wood fibre, and cellulose were compared with results from tests on specimens with glass wool and stone wool. The thermal insulation products based on PIR, wood fibre or cellulose used in these experiments are combustible, with reaction to fire class E according to the classification. Glass wool and stone wool used in these experiments are both noncombustible insulation products with reaction to fire class A1.The evaluated insulation products reacted differently to high temperatures; the insulation products of PIR, wood fibre and cellulose tended to char and burn. While glass wool becamediscoloured and melted, stone wool became discoloured and porous, but neither of themburned and contributed to the fire.The results show that a char layer formed during combustion of PIR, wood fibre and cellulose will slow down the temperature increase inside the insulation. Combustible insulationproducts, as tested in these constructions with a protective cladding, can provide fire protection by slowing temperature increases inside the insulation and on the surface of the timber structure in the construction. Measurements from the non-standardized fire tests show thatconstructions with these tested insulation products can also achieve similar or better insulation performance compared to the tested glass wool and stone wool insulation when the insulation thickness is the same. However, in some cases the stone wool and glass wool insulation gave slower temperature development and better fire protection of the timber structure. Because the thermal conductivity of PIR is lower than the other products used in the experiments, it will sometimes be installed in smaller thicknessesthan the other insulation materialsinside wall and roof constructions. The thermal insulation for the constructions with PIR in the current tests is therefore better than the other tested constructions.The EN 1364-1 tests showed that higher temperatures were registered for batts than for loosefill insulation of the wood fibre and cellulose products used in these test series. Therefore, loosefill insulation was assessed to be more fire resistant, which motivated the present study to consider batts as the more challenging product. Batts were therefore used in the wall and roof constructions tested at RISE Fire Research.The temperatures in the roof construction increased faster than in the wall due to the temperature and pressure gradients inside the test furnace and the sagging and fall-down of the insulation. This demonstrates the importance of correctly installed insulation.According to the results from the SBI tests, the consequences of damages or holes in the cladding at the start of a fire are mainly limited to local fire damages in the insulation and short flame spread behind the cladding. The combustible insulation materials had limited fire spread laterally from the exposed area. There was, however, extensive damage in the direct fireexposed area, ranging from 40 to 100% charring through the insulation thickness. The specimens with glass wool and stone wool experienced no charring but were discoloured through 70 to 80% of their thickness by soot and possibly combustion of the binder. Classification according to EN 13501-1 does not reflect the heat transport into and through the construction and insulation. An estimation of thermal insulation products' fire performance is, therefore, not possible based only on this classification. This is, however, not the purpose of the reaction to fire classification given by the standard, but some users might assume that products with the same classification perform similarly in a fire, which is not necessarily true. Combustible insulation materials can contribute to the development and spread of a fire and cause increased smoke production. Smoke production has not been studied in these experiments but must be considered when using such products. However, whether the insulation is combustible or not, the required fire resistance for both loadbearing and fire separating constructions must be ensured to prevent structural collapse and fire spread to other parts of the building.

(2) Fire protection performance of claddings used on combustible insulation The goal was to determine the effect of fire protective claddings when installed on different types of insulation.The non-standardised tests showed that a 13 mm Norgips Standard gypsum board type Acladding with classification K210 A2-s1,d0 provided approximately 7 minutes longer fire protection compared to a 12 mm plywood board cladding with classification K210 D-s2,d0. The gypsum board and the plywood board protected the insulation for approximately 17 and 10minutes, respectively.

(3) The fire performance of the transition between the wall and roofThe goal was to investigate the fire performance of the transition between claddings on the wall and in the roof. The non-standardised tests showed that the transition between the walls and roofs performed well, i.e., this was not a weak spot where the fire burned through to the insulation faster than through the cladding.The results obtained in this research project are based on the insulation and cladding products tested here. Other products of similar materials might have different fire performance.

This study aims to experimentally investigate the combustion products of fires suppressed/extinguished by two water-based fire suppression systems, namely, sprinklers and water mist systems. A total of thirteen experiments were conducted with various suppression system configurations, i.e., with a sprinkler, a low-pressure (LP) water mist, and a high-pressure (HP) water mist, at operating pressures ranging from 2 to 60 bar and water flow rate ranging from 10 to 206 L/min. Each experiment was conducted twice, except for the baseline experiment with no suppression. The fuel was a high-density polyethylene (HDPE) pallet placed on two wood pallets. During all the stages of fire development, suppression with water, and post-suppression, the combustion products were sampled through Fourier-Transform Infrared Spectroscopy (FTIR) using a gas analyzer capable of operating in high humidity. The main combustion products identified were CO2, CO, and H2O. In addition, NOx (nitrogen oxides), CxHy (light-weight hydrocarbons), and HCN were present in relatively high concentrations. All the tested fire suppression systems were effective in reducing the fire size and cooling down the gases. However, when the fire could not be immediately extinguished, the NOx, CxHy, and HCN concentrations were higher than those in the baseline experiment. Moreover, it is observed that the HP water mist system was more effective than the sprinkler and low-pressure water mist systems in reducing the amount of combustion gases during suppression, resulting in lower Fractional Effective Doses (FED). It was observed that the combustion products returned to ambient conditions after five minutes of deactivation. The results from this study provide much-needed validation data for the effectiveness of water-based suppression systems, not only in reducing the fire size but also in reducing the production of acute toxic gases, which is important for considerations regarding evacuation, firefighting, and post-extinguishment conditions. .

Wildfires in Scandinavia are predicted to become more frequent and severe [1,2], necessitating a deeper understanding of the fire behaviour in scenarios unique to local conditions. Therefore, the Norwegian Pilot in the EU-funded wildfire project TREEADS focuses on understanding fire dynamics and fire spread mechanisms inherent for Norwegian wildfires and develop a relevant and scalable lab test method to document the fire resilience of materials against wildfires.

The Scandinavian countries have in later years seen several severe wildfires and is expected to exhibit more severe fire danger. While direct flame spread has been an important topic in wildfire research, there is a need for development and to ensure that experimental methods are relevant for Scandinavian wildfire characteristics. To ensure relevant lab conditions for fire-resilient material development work, large lab-scale (2×4 meters) experiments were conducted on various fuels. Its fire behaviour (such as rate of spread, fireline intensity and flame length) was compared with ongoing wildfire field studies from ongoing field studies in boreal and hemiboreal Sweden. The lab fire experiments show good potential to mimic relevant natural wildfire conditions in the laboratory once a standard design fire exposure for fire resilient materials is developed.