Some concluding remarks
A review of previous studies into smoke management for dwellings, corridors, lobbies, stairwells, together with current practice and trends, has been completed. It provided an important input into the choice of fire scenarios and smoke management schemes to investigate in the experimental and numerical modelling programmes of the current research project into the smoke ventilation of common access areas of flats and maisonettes, allowing a set of generic geometries to be proposed, together with the associated smoke ventilation measures.
Smoke management of the common access areas can be divided broadly into that required for the corridors and lobbies, for the stairwell(s) and finally for the lift shaft(s). The focus for the current project is on the corridors and stairwells, for which the range of options available has been reviewed with the emphasis on the appropriateness for residential premises in the UK. While some attention has been given also to smoke management measures that can be used in the compartment of fire origin, these were not pursued further in the current project.
While stairwell smoke management was provided originally by natural ventilation, with combinations of vents at the top, base or at intermediate levels, the worldwide trend over the past decade or so has been towards mechanical pressurisation measures. When properly designed to account for building stack effects, open doorways etc, these schemes can provide smoke-free conditions inside the stairwell for egress and fire- fighting operations. However, in scenarios where absolute smoke-free conditions are not critical, or simplicity of design and maintenance issues are of importance, natural smoke ventilation of the stairwell is still a valid option.
Common corridors and lobbies can also be protected directly by pressurisation systems. However, for residential premises the practice is more generally to provide either natural or mechanical ventilation, or to provide no smoke ventilation measures. In the latter case, it is assumed that the travel distance is sufficiently short or the conditions not too onerous, so that evacuating people can each a stairwell or other area of safety without undue ill effect. This may require, however, that all persons on the fire floor evacuate at an early stage.
© Building Research Establishment Ltd 2005