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Technical
How does fire engineering deal with operational changes to buildings?
Beth Corrigan Mott MacDonald
Adding champagne bars to stadium concourses or skateparks in shopping centres may sound like fun projects, but such building changes create fire engineering challenges. Mott MacDonald’s Beth Corrigan explains
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Fire engineering is essential to demonstrate that a building design is compliant, but operational decisions over the building’s life can affect its actual performance.
These changes can be accounted for during the design stages through early involvement of fire engineers and the use of the right software and information management tools, as well as early end-user consultation.
Performance-based fire engineering is developed around a defined set of assumptions: occupant numbers and behaviour, management arrangements, maintenance regimes, housekeeping standards and a known fire load. The problem is not that those assumptions are wrong, but that buildings rarely remain unchanged.
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Once the keys are handed over, changes like adding champagne bars to stadium concourses or skateparks in shopping centres can pull the building away from the scenario the fire engineer modelled at the outset.
Creating a ‘golden thread’ of information is vital to implementing a robust fire safety design that bridges the gap between design intent and the changes that come through real-world use.
For new buildings, the considerations needed to balance design with operational reality can be incorporated into the strategy at the design stage with flexibility for future changes. For existing buildings, proposed changes must be carefully considered and reviewed to ensure clients can satisfy their fire safety duties and responsibilities without adversely impacting occupant safety.
Understanding what might change
For large, complex assembly buildings such as airport terminals, shopping centres and sports stadiums, customer needs are constantly changing. This can prompt building owners to seek more innovative and exciting ways to enhance the customer experience and increase revenue streams.
As an example of the types of changes that could occur and their impact, consider the designs of sports stadiums, which are historically based on large open-air concourses. These were designed to be fire sterile, with food and beverage concessions located behind fire shutters.
However, as stadium owners look to provide enhanced experiences, food carts might be located in the concourse and the conventional ‘fire sterile, fire separation’ approach is no longer possible. This has the potential to impact the stadium’s evacuation strategy, but using fire engineering principles, it can be safely implemented with sufficient mitigation and engineering analysis.
Performance-based design is important for demonstrating building safety at the design stage. Use of modelling, such as zone modelling or computational fluid dynamics, can be key to demonstrating that the building can remain safe in the event of a fire when changes are implemented, or guide use of mitigation systems, including sprinklers or smoke control systems, to improve safety.
However, it is not always possible to safely accommodate all changes in use. Therefore, it is essential to manage client expectations by being clear about limitations and offering alternative solutions. Where the solution pushes the boundaries of what has been done before, it is critical to engage with local approval authorities early. This helps to reduce the risk of abortive work and client disappointment, while allowing the authorities to be part of the journey so they can make informed decisions.
Challenges set to increase
The next five years are likely to harden expectations around evidence, competence and accountability, particularly post-Grenfell. The government’s Fire Engineers Advisory Panel, established last year, may result in significant changes to the role and competency of the fire engineer.
However, the construction industry as a whole, not just the work of fire engineers, is being scrutinised more closely.
“The higher risk building definition focuses on taller residential buildings, but it is not difficult to see why higher risk buildings such as stadia and shopping centres might be in scope in the future.”
The Building Safety Act has already pushed the industry toward clearer justification and better information management, but that may be expanded in the future. Today, the act’s higher-risk building definition focuses on taller residential buildings and hospitals, but it is not difficult to see why higher-risk buildings such as airports, stadiums and shopping centres might be included in the scope in future.
The result of all these changes may be that there is less appetite from approving authorities to consent to fire-engineered solutions. In turn, this may result in more operational constraints for clients, making significant changes to a building more difficult.
To overcome these challenges, it is essential that fire engineers are involved in the early design stages and all relevant stakeholders are included in discussions so the design can be as flexible as possible. End-users’ requirements and management constraints need to be incorporated to future-proof designs and develop a realistic fire strategy. This will help address potential for change at the outset and move away from fire engineering that only focuses on day one of a building’s operation.
Beth Corrigan is principal fire engineer at Mott MacDonald.
