There are over 180 fire incidents in Norwegian schools per year. Even though most of these fires are small, they can still produce a large amount of smoke. Ideally, the existing comfort ventilation systems would be used to control the smoke movement from these fire spreads to increase fire safety and limit the damage. Traditionally, this has been done by closing both exhaust and supply ducts to prevent the smoke spread to other rooms. However, this solution can be expensive because it requires fire-rated dampers to ensure that the ventilation ducts are closed properly. Furthermore, closing these ducts during a fire can also lead to a pressure-buildup that makes it difficult to open or close doors, thus complicating evacuation process.
The BRAVENT project will explore how well suited the existing ventilation systems are to control smoke spreading and to ensure fresh air in escape routes. The strategy to be investigated is to use the comfort ventilation system to extract smoke instead of shutting down the ventilation system with fire dampers. This strategy may be especially suited for the most common fires in schools, namely small fires with moderate heat generation.
However, there are some challenges associated with adapting the extraction strategy for schools. For example, building layouts vary significantly, and this results in a corresponding difference in the ventilation systems. In addition, smoke extraction may lead to soot accumulation in the ventilation system, which can compromise the indoor climate.
The project started at Q2 in 2021. During the first year, the project began to map ventilation systems in schools in Oslo, Trondheim and Bergen, as well as to collect information about reported fire incidents in schools. Tests of the ventilation system in selected schools have been conducted to document the function of the ventilation systems during a fire alarm. The ventilation was tested during different scenarios (e.g., normal operation, night mode). Further tests in additional schools are planned.
The project will establish a best practice ventilation solution that ensures efficient smoke control in the event of a fire. The potential for soot accumulation will be assessed through fire testing of the key ventilation components. Finally, the effectiveness of the extraction strategy for small fires will be verified through large scale fire experiments and computer simulations.
There are over 180 fire incidents annually due to arson in Norwegian schools. The fire service responds annually to some 110 fires in schools. Most fires are minor in terms of heat release rate and damage caused by heat, but substantial amounts of smoke can be produced, which may cause damages beyond the room of origin.
The public sector reports that a lack of design guidelines has caused a wide spread of different ventilation strategies and systems in their buildings. Additional challenges occur when older buildings are modernized with new ventilation and control systems that need to be adapted to the existing constraints of the buildings. System tests conducted in schools have shown that the ventilation system's fire mode disturbs the pressure balance in the building to an extent where self-closing doors will not close and closed doors may not be opened due to pressure differences. During evacuation, this may lead to smoke spreading through doors that was intended to close and that evacuation routes are blocked.
The innovation concept of this project is to use the existing comfort ventilation system to control smoke and pressure in the event of small-size fires schools. With the increasing complexity of the ventilation systems, ventilation systems check-ups have become a daunting task for building managers, particularly in buildings with fire dampers, as they are typically installed in not easily accessible areas and are hard to test and reset. The innovation includes a control plan to evaluate fire safety of the existing ventilation system and a guideline on how to design a cost-effective fire safe ventilation system. Such concept can be easily adopted to all buildings equipped with comfort ventilation system.
If the proposed concept is proven to be effective, not only a better pressure and smoke control can be achieved during a fire, municipalities can reduce installation and maintenance cost by reducing the dependence on fire dampers.