Post-flashover fires inherently lead to external fire plumes, constituting a hazard for rapid fire spread over façades. As multi-storey mass timber buildings with internal visible timber surfaces become more common, there are concerns that such buildings would produce larger external plumes and hazards (assuming all other parameters equal). The literature reveals only indications of this, and how the actual exposure relates to different test methods for assessment is unknown. Here we utilise a series of full-scale mass timber compartment tests to quantify the exposure to the external façade. An incombustible external façade is instrumented with gauges at positions corresponding to reference data from several different assessment methods. The results show that there is an increase in plume duration, height, and temperatures when increasing the areas of exposed timber, but that this increase is less for normal- to large-opening compartments, than was previously seen in small-opening compartments. Also, normal variations in external wind speed have a larger influence on plume heights than the effect of doubling exposed timber surfaces. Test methods used for regulatory compliance differ significantly not only in exposure but also in pass/fail criteria. The proposed European large exposure method and the BS8414 method exhibit exposures on par with the severe end of what could be expected from mass timber compartments, whereas methods like SP Fire 105 and Lepir II produce significantly less severe plumes. However, the safety level is always a combination of exposure and assessment criteria. This data can help justify assessment criteria from a performance perspective. © 2023 The Authors. 

The project BREND investigated risk with alternative fuel vehicles inside ro-ro spaces. BREND 2.0 is a continuation and has in particular investigated two of the major risks identified in BREND, namely the risk of toxic gases from electric vehicle fires and the risk of a pressure vessel explosion for fire exposed biogas or hydrogen vehicle tanks. Simulations of electric vehicle fires inside a ro-ro space based on real input fire data has been performed. Field experiments that investigate the conditions that can lead to pressure vessel explosion were made with fire exposed biogas and hydrogen tanks. Recommendations are given about how ro-ro space fires in alternative fuel vehicles, or indeed any vehicle fire, can be managed.

Electric vehicles (EVs) and other vehicles with alternative energy carriers (such as hydrogen) are becoming increasingly common, and with them new fire risks. This report provides the technical details of computational fluid dynamics simulations carried out as part of the BREND 2.0 project to assess the tenability conditions within a ro-ro space from EV fires, via assessment of temperatures, radiation and spread of toxic species. The simulations primarily considered variation in compartment ventilation and fuel source. In all scenarios a selection of gaseous species, gas temperatures and radiative intensity are recorded at point locations and as 2D slices across the ro-ro space. From the gaseous species fractional effective concentrations, for irritant gases, and fraction effective doses, for asphyxiants, can be calculated to provide an assessment for tenability conditions in each scenario. This report contains the results of the simulations and some general observations but no detailed analysis of the implications of the results in terms of safety of EV fires on a ro-ro space.

Thermal propagation is one of the major challenges when batteries will be used in dwellings in large scale. It means the exothermic reactions in the cell are out of control and can lead to a fast release of flammable and toxic gases. In a system involving a large number of cells, thermal runaway can rapidly propagate from one battery cell to the whole system, which means substantial fire and explosion risks, an event that is important to mitigate and prevent. Multi-physics simulations together with full-scale testing is a cost-effective method for designing safer batteries. This project aims at simulating thermal runaway initiation and propagation using a multi-physics commercial software GT-Suite. 

A battery thermal runaway model containing 12 prismatic cells based on 3-D Finite Element approach was built using GT-Suite. The computed thermal runaway time instants versus thermal runaway cell number were compared with full-scale experimental data with reasonable agreement. Quantitative sensitivity study on the model input parameters and model space and time resolutions on the computed start time instant and time duration of thermal runaway were performed. The thermal runaway model was then extended with an electric equivalent sub-model to simulate the short circuit. With the electrical model acting as the input to the thermal model, the most interesting output of the simulation is the change in temperature of the cells, dependent on the current in the cells, with respect to time. The current is determined by the value of the external resistance through which the short takes place and the voltage level of the battery pack. The obtained results from the above short circuit simulations can only be used as a starting point and not as absolute values for neither triggering the thermal model nor for accurately simulating a battery under an electrical load. Furthermore, GT-Suite was applied to simulate the gas dispersion inside a room. A comparative study of the dispersion of toxic gases during thermal runaway, utilising an arbitrary release of HCN to represent the battery gases, in a small compartment with natural ventilation was investigated and the results compared the same situation simulated in FDS. The pipe based modelling supported by GT-Suite has limited applicability and overestimated the concentrations close to the ceiling whereas the lateral concentrations where underestimated. 

The multi-physics model for battery thermal runaway process is promising and worth to be applied with care for designing safer batteries in combination with full-scale testing. 

The level of protection for personal protective equipment (PPE) in firefighting is important for Swedish shipowners; they want to be sure that the equipment they provide is sufficiently safe for the types of fires that can occur onboard. Shipowners also want to be updated on risks related to the carriage of alternative fuel vehicles (AFVs). Safety products and equipment used onboard ships with a European flag must be certified in accordance with the Marine Equipment Directive (MED) and follow the regulations in the International Convention for the Safety of Life at Sea (SOLAS). For fire suits, this means that they must be certified according to one of three standards listed in MED. Two of these standards cover suits used in special cases, with very intense radiant heat, and should only be worn for short periods. The third standard, EN 469, is the same standard that is referred to the PPE Regulation 2016/42, making EN 469-approved fire suits used among European firefighters ashore. However, EN 469 contains two different performance levels where the lower level is not suitable for protection against risks encountered when fighting fires in enclosures. Based on a user study and a risk assessment for AFVs, a set of suggested changes to MED and SOLAS were prepared, together with a set of recommendations for operators that were found important but not subject for regulations. A ready-to-use quick guide, containing the most important results, has been developed for operators.

Façade fire testing has been high on the agenda worldwide due to the increased hazard of many occurrences of severe fire spread on façades. There is also international work going on to create a European standard for façade fire testing. In this context it is interesting to clarify what different national test methodologies are based on. This report is a review of the development that led to the Swedish standard for assessing fire performance of façades, SP Fire 105. The review starts from the development in the 1950s with assessing fire exposure from compartment fires and follows further development until 1990s. The fire exposure in the first edition of SP Fire 105 published 1985 was based on two test campaigns including external flames from room fires performed at Lund University during the late 70-ties and early 80-ties. In the early 90-ties the geometry of the air intake in the combustion chamber and the opening under the test specimen was slightly reduced leading to a lower effective thermal exposure of the façade than in the first edition of SP Fire 105. An important observation done already in the 1950s at the Swedish fire laboratory in Stockholm and in the late 1970s at Lund University was that the wind is influencing the test results when doing experiments outside.

The aim of this project is to provide the basis for risk assessments relating to the risk of lithium leaks in the DONES project. This report firstly summarizes the current knowledge of risks and reaction features at different scales with liquid lithium. Note that the review is limited to fire behaviour of lithium in its liquid state and does not consider additional risks connected with breeding tritium or corrosive effects of impurities. Some of the questions important for this project are to limit the lithium reaction with water, limit the spread of fire started by a reaction with lithium and extinguish flame of lithium induced fires. The second part of the report consists discussion of some initial small-scale experiments, undertaken to provide a basis for limiting the extent for further larger tests, and a proposal for an experimental device where lithium reactions can be studied in a controlled environment, i.e. with controlled amount of oxygen, nitrogen or humidity in the experiment. This will then be the basis for risk assessment for liquid lithium loop in the DONES facility.

Different countries world-wide have different legislation concerning the performance of facades exposed to fire and often significantly different ways to assess this performance. Although it is recognized that standard façade fire testing aims to distinguish façade systems that limit fire spread to an acceptable level from systems that do not, it has historically been considered important that the fire exposure of such tests is representative for real fires.

In this study five real scale compartment fire tests, constructed of Cross Laminated Timber and Glued laminated timber were performed with instrumentation on a façade extension above the ventilation openings, providing a means to compare façade performance tests against the exposure generated by realistic compartment fires. The fuel load and openings of four of these tests were determined from a statistical analysis to represent severe fire exposure within a realistic range. Of these tests the surface areas of exposed Cross Laminated Timber and Glued Laminated Timber were varied, allowing an assessment of the influence having internal areas of exposed timber surfaces on the façade fire exposure.

For these tests, an increase of roughly 40 m2 exposed surface area (from ~54 to ~94 m2 or from 113 % to 196 % of the floor area) resulted in a temperature increase of roughly 100 to 130 °C at the façade at all heights up to 3.5 m above the opening. Additionally, an increased fire plume height of 0 to 1 m was observed. The most significant effect of increased exposed areas was a prolonged duration of the flashover phase.

The British BS 8414 standard façade fire tests and the recently proposed European façade fire test have been identified to be the most representative for the tested residential fire scenarios in terms of façade fire exposure. Temperature measurements of the North American methods (NFPA 285 and CAN/ULC-S134) are towards the end of the tests also close to the those of the compartment tests. The Swedish SP Fire 105 test imposes the lowest exposure for a relatively short duration to the façade. It should, however, be noted that a lower exposure in the standard test method does not with necessity mean lower threshold for regulatory compliance as the test criteria also differ between different countries.

One of the tests were characteristic of open plan office buildings and it was shown that the fire exposure is both shorter and lower compared to typical residential compartment tests. All standard tests that were used for comparison here exhibited both longer and higher exposure than the office building compartment test.

The present paper investigates a travelling fire scenario in an elongated structure (Length 18 m × width 6 m × height 3 m) with a controlled fire source of six trays filled with diesel (width 4 m × length 0.5 m). The fire spread is controlled manually by initiating fires consecutively in the pools. Fire dynamics simulator (FDS) is used to a-priori investigate variations in geometry, material data and fire load, whereas simulations using the final design and measured heat release rates (HRR) were performed after the test. The input to the model beside fire source and geometry are thermal material data. The FDS simulations were used to determine the appropriate size of the downstands (2 m from the ceiling in the final design) on the side to create a sufficiently one-dimensional fire spread. The post-test simulations indicate that although there are a lot of variations not included in the model similar results were obtained as in the test.

Five real scale fire tests of compartments constructed of cross-laminated timber (CLT) and glued laminated timber, compliant with product standards specified in current US model building code, were performed. Four of the tested compartments were designed to result in a representative and severe fire scenario in a residential fire compartment, using a probabilistic approach. The other tested compartment had additional openings and a greater opening factor, which was aimed to be representative of buildings designed for business occupancy. The interior of the compartments had surface areas of exposed mass timber that varied from approximately the area of the floor plan to approximately two times the area of the floor plan. The tests included measurements to study the internal compartment exposure, the temperature development at gypsum protected surfaces, the temperature development in the structural timber, oxygen concentrations at locations of interest and exposure to exterior surfaces of the wall and façade above the openings. The fire in the compartment with a greater opening factor had two layers of fire-rated gypsum board protection on the back wall and all other surfaces of CLT and glued laminated timber exposed. Despite having the highest peak combustion rate, this compartment fire had the least severe internal and external fire exposure. The fire decayed relatively quickly after flashover and continued to decay until the test was stopped at 4 hours after ignition. This fire resulted in less structural damage than the fires in compartments with fewer and smaller openings. The compartments with fewer and smaller openings had similar temperatures for approximately the first 10 minutes after flashover. The compartment with only the ceiling (including the glued laminated timber beam) exposed started to decay after 22 minutes of post-flashover fire and continued to decay until the end of the test at 4 hours after ignition. The other three tests had, in addition to the ceiling, significant areas of exposed wall and column surfaces. To accommodate for the extended fire duration that was expected in these configurations an extra layer of gypsum board protection was applied to the protected surfaces. The additional exposed surface areas of walls led to an increase of the fully developed fire duration by 6 - 9 minutes. One of the compartments included corners where two exposed walls intersect. Significantly increased damage was observed in the lower part of these wall corners, and an overall higher radiative exposure in the test with such corners. After more than three hours of decay, surface flaming developed on the walls in that test. The fires in the tests without such corners exhibited continual decay for the full 4-hour test duration. Post-test analysis showed that the structural damage was lower in exposed ceilings than at the bottom of the exposed walls for all tests. After the tests, remaining smoldering and hot spots were reduced using relatively small amounts of water mist. Overnight measurements to study the thermal wave going through the loadbearing structure indicated no post-test reduction of structural capacity.