We have successfully used this framework and assessment to build Alternative Solutions for exit exposure in buildings where the water supply was insufficient to add sprinkler heads for a water curtain solution.
We’d be happy to help you determine if this solution would work for your exit exposure condition.
Author: Stefan Germann, P.Eng.
Abstract
This paper details of the development of a framework and assessment tool that can be utilised:
In lieu of the prescriptive requirements detailed in building codes that require fire resistive barriers to separate exit routes from the radiative effects of fire and/or
To address egress past a burning object in an open floor area.
Contained within this paper is a methodology that can aid the user in:
Determining the level of radiation from a fire source imposed on an egress route that is adjacent to the source, and
Determining if the level of radiation will result in sufficient pain to prevent the use of the egress route.
Generally, the calculations are based around quantified fire engineering formulae and good engineering practice.
Introduction
Safe occupant egress under fire conditions is a fundamental requirement of any building fire safety design. Here in Canada, as well as in other countries around the world, this is typically addressed through the use of physical barriers that provide a level of fire resistance via solid construction or by sufficient separation distance. These measures aim to limit exposure conditions, regardless of whether the exit route or means of escape is internal to, or external to the building. The general exception to this is in open floor areas within a room or space within a building.
The use of solid construction or separation distance sometimes conflicts with the architectural vision of a building or space. This can become an issue when occupants are required to travel past a window opening along an exit route or an internal/external egress route where only a single path of travel is provided, as openings could expose occupants to expose occupants to high levels of heat which could delay or prevent egress.
Windows and other openings adjacent to egress routes are permitted provided they are either protected with appropriate closures or separated by sufficient distance from the egress route. Of particular consideration in British Columbia is the prolific use of water curtain alternative solutions to address the exposure hazard when either site constraints (separation distance) or architectural features (windows or other openings) don’t align with the prescriptive requirements. While water curtains can limit the exposure hazards through window openings and cool hot fire gases, these are typically used in buildings that are already provided with a sprinkler system, and would not provide much, if any, benefit compared to the complete sprinkler coverage that is already provided [1]. Additionally, water curtains can be hydraulically demanding as they are generally required to be calculated in addition to the base building floor area sprinklers.
The discussion below lays out a framework and hazard assessment tool using good engineering practices to address the design issue of occupants egressing past a window opening or a fire within an open floor, when a closure is not provided or there is not sufficient separating distance.
The main goal of the framework and hazard assessment tool is to assess the expected level of radiation from a fire that would be projected onto an occupant walking by to determine if the egress route is passable. While similar approaches are used internationally this framework is aimed specifically towards the regulatory system in Canada.
The framework and tool identify acceptable levels of performance and acceptance criteria based on sound fire engineering concepts to meet the objectives identified in the Building Code, as opposed to the prescribed Acceptable Solutions.
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