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Fire, Life Safety

Creating fire safety resilience

Collaboration and specialized design considerations will provide resilience for more buildings and cities as they prepare for fire and other events impacting life safety

By Mackenzie Hill August 14, 2020
Courtesy: Christine Pongratz, Arup

 

Learning Objectives

  • Understand that a measure of fire resilience is inherently built in the applicable codes and standards.
  • Appreciate that a holistic view of resilience requires understanding the cascading effects of hazards as well as an impact variance dependent on vulnerability.
  • Learn about the tools available to aid the discussion between governments, owners and developers with designers, consultants and contractors to assess current resilience capabilities, set resilience and life safety goals, incorporate resilient solutions and improve life safety.

The topic of fire and resilience has been and currently is at the forefront of many people’s minds, well before a pandemic, quarantine and protests. As fall is quickly approaching, the thought of fire is typically paired with fond memories around camp fires, a cozy evening in front of the fireplace or the looming devastation of wildfire season. The idea of resilience typically encompasses risk management, applying additional measures to account for the hazards and reducing losses associated during and after an event.

Resilience, for the purpose of this article, will be defined as the ability of systems to adapt and mitigate current and future shocks and stresses. This definition can then be applied to different aspects related to scale for individuals, buildings, communities and cities to adapt. It can be applied to shocks and stresses such as fire, flood, seismic, wind or human-created events and the impact the shock and stresses have. Though resilience is involved in all aspects of the aforementioned scales and topics, the focus will be on buildings and cities as it relates to fire and life safety.

One way to reduce the impact of a fire on life safety is to learn from the past. Historically, out of great tragedy comes the greatest development of the building codes and increased safety measures. This can be seen through some examples in history.

The Great Fire of London, which destroyed the majority of London in 1666, lead to the creation of the first firefighters (fire brigade) and the London Building Act of 1667. The building act required noncombustible construction from brick and stone, restricting wood and thatch use, increased the width of streets and limited the stepped construction and overhangs over the streets, among many other design considerations and requirements. The fire brigade contributed to fire safety and fire resilience at the building scale and city scale.

The Great Chicago Fire of 1871 also destroyed much of the wood-built city. After the fire, Chicago city officials mandated the use of fire-resistant construction materials for new buildings and the iron industry developed fire-proofing of steel construction, which has since transformed skylines around the world.

The collapse of the World Trade Center reshaped how the U.S. and the world looked at terrorist threats to buildings and security. The investigation conducted by the National Institute of Standards and Technology produced a report, “Status of NIST’s Recommendations Following the Federal Building and Fire Investigation of the World Trade Center Disaster.” The report discussed 30 recommendations for building codes and standards, many of which were implemented during the following code cycles. The recommendations for high-rise buildings taller than 420 feet included improved structural integrity, increased fire resistance and fireproofing bond strength, redundant water supply risers for each sprinkler zone, an additional egress stair, egress path illumination and provision of fire service access elevators.

The loss of life and tragedy of the events listed above have shaped and influenced how buildings are designed. The modification and implementation of current building codes and standards fundamentally incorporate a level of resilience into future buildings, adapting the code to account for what was previously lacking to reduce the risk of future fire events and improve life safety.

Codes and standards for resilience

The purpose of the building code is to provide uniform minimum requirements to protect the public health, safety and welfare of the occupants in buildings and structures. Building codes and standards provide an expected level of safety related to the construction of the building and the life safety measures inherent in the design, which accounts for many individual disrupters at the time the building is designed and constructed.

However, as seen with the recent California wildfires, some communities that were designed per the guidance in the California Building Code for buildings in the Wildland-Urban Interface (CBC Chapter 7A) succumbed to the intensity, speed and overall devastation of the wildfire. Certain jurisdictions in the Wildland Urban Interface outside of California may adopt the International Wildland-Urban Interface Code.

Most building codes and jurisdictions only consider structure fires and not the shock of wildfires. This is a gap not addressed in the planning codes, zoning laws and building codes that the recent wildfires have highlighted with devastating consequences.

While adhering to codes and standards does not guarantee life safety, it is the objective. But extreme events or cascading hazards may overwhelm fire and life safety systems. Unanticipated hazards or human behavior may also compromise life safety.

While building design and construction is required to comply with relevant codes and standards, is there sufficient resilience built in the design to account for the potential shocks and stresses the building will experience during the buildings expected life cycle and operation? Are the ways the buildings operate, managed and maintained providing sufficient flexibility and resourcefulness in their procedures and design for the occupants within the building to withstand various shocks and stresses?

It is noteworthy to mention that the building code typically does not require the building design to incorporate multiple failures simultaneously, other than power requirements and some specialty use requirements (e.g., emergency power and high-rise buildings).

For example, the fire pump is sized to accommodate the single worst design area based on flow and pressure requirements. These maximum requirements may occur in the same area or two different locations based on the system demands, but only one design area is considered flowing at one time. When a fire event occurs in a building, it is expected that there will only be a single fire and the fire will be contained by the operation of a single design area.

Because the code requires building designers to look at the building for isolated events or a specific combination of failures, the same typically applies to the owners and clients unless they have corporate or insurance requirements or until an unpredictable multifaceted disruptive event occurs that negatively impacts life safety or business continuity.

Disruptive fire or other events

Some of the disruptive events to evaluate when considering resilience should include natural hazards and man-made hazards, as well as combinations within and between each. Natural hazards would include but are not limited to the risk associated with wildfire, seismic events, floods and wind (hurricanes and tornadoes). Man-made risks include failure of systems created by humans: power failure, loss of water supply and communication failure; or caused by humans: active shooter, arson and terrorism.

Examples of disruptive events occurring simultaneously:

  • An earthquake causes the building water supply to break, negating the fire suppression system. A fire occurs in the building due to the damaged electrical system. The smoke and fire could then travel through the building where the elevator shaft walls and egress stairs are disjointed after the seismic event because the seismic bracing failed as it was not sized to withstand the force of the earthquake.
  • Elevated tension related to unforeseen circumstances lead to a person to have irrational anger toward a department distributing the limited available resources and becomes an active shooter in that business.
  • Severe winds and hot temperatures cause significant loads on utility power lines and transformers, which leads to the system creating sparks that are carried by wind beyond the noncombustible platform. This ignites adjacent vegetation, transforming from an ember to unmanageable wildfire in hours with the potential to destroy entire cities, displacing thousands of people.

There are significant amounts of individual potential shocks and stressors and the potential of cascading hazards as described above, the idea of designing for resilience may seem daunting. If governments, developers, design professionals or building owners want to design for resilience, the questions become: Where should resilient design start? What elements should be the priority for resilience? Is there a way to quantify that priority?

Figure 1: The City Resilience Index wheel shown outlines the four dimensions and 12 goals to assess resilience. Courtesy: Arup

Figure 1: The City Resilience Index wheel shown outlines the four dimensions and 12 goals to assess resilience. Courtesy: Arup

Designing a resilience index

The City Resilience Index, developed in partnership with the Rockefeller Foundation, is the world’s first comprehensive tool for cities to understand and assess their resilience strengths and weaknesses, enhancing their ability to shape policy and prioritize investments to become more resilient places. The City Resilience Index is a comprehensive approach based on extensive research and collaboration with experts and cities around the world and their partners to analyze and determine a city’s resilience profile and compare the city’s performance over time.

The research included a literature review of 150 references, 45 frameworks and 14 cases studies. Data were compiled from 24 cities, with the majority of information used from six cities and engagement with 45 experts from a range of industry specialties. To date, more than 200 cities around the world have used the City Resilience Index approach to understand their resilience strengths and weaknesses, further validating what matters most to how a city functions when facing chronic stresses or sudden shocks.

The structure of the City Resilience Index is graphically symbolized as a wheel stemming from four dimensions, which is the foundation in determining resilience of a city: health and well-being, economy and society, infrastructure and environment and leadership and strategy.

As designers and engineers, the most influence to the City Resilience Index is in the infrastructure and ecosystems quadrant where the indicators include reduced exposure and fragility, effective provision of critical services and reliable mobility and communications. This is where building and planning designs have the most impact and can incorporate robust and redundant systems to account for potential shocks and stresses. Designs will implement the applicable codes and standards and apply an appropriately scaled hazard analysis expected for the local area. However, being mindful of the other quadrants and how all are integrated with one another will build on the overall resilience of the city.

The four dimensions are then correlated to 12 goals determined by 52 indicators or contributing factors to achieve resilience. Each indicator typically has three assessment questions, 156 in total, which could be answered for a qualitative or a quantitative analysis. Using a qualitative and quantitative approach allows cities to measure its current performance as well as project the impact the mitigating factors being implemented will have on a more resilient future.

The qualitative aspect of the assessment accounts for a range between the best and the worst case based on the specific indicator. The qualitative questions provide an understanding of the current situation and the general resilience trajectory of the city. Measuring city resilience as a quantitative approach can only truly occur following a real shock or period of stress. The assessment at the time of the event becomes the benchmark that allows the city to identify areas within the City Resilience Index that need to be improved as well as compare the city’s performance over time.

Figure 2: The Framework for Fire in Informal Settlements wheel showcasing the disaster cycle and resilience assessment factors. Courtesy: Arup

Figure 2: The Framework for Fire in Informal Settlements wheel showcasing the disaster cycle and resilience assessment factors. Courtesy: Arup

The City Resilience Index defines city resilience as the capacity of cities to function so that the people living and working in cities — particularly the poor and vulnerable — survive and thrive no matter what stresses or shocks they encounter. This resilience approach focuses on enhancing the performance of social and systemic issues in cities, which may not be experienced by the majority but significantly impact the most vulnerable and marginalized. The City Resilience Index also considers the impact of multiple hazards on the city rather than the loss of a single structure due to an event.

Fire hazard resilience frameworks

Arup has worked on multiple projects and internal research to consider specific hazards to develop frameworks and designs to create resilient solutions. These frameworks include energy resilience, climate risk and adaptation, water resilience, child-centered urban resilience and fire safety in informal settlements. Arup’s advance technology and research team has created a rating system framework for resilience-based earthquake design initiative (REDi Rating System). It informs owners and designers of various criteria that would need to be achieved so that, after a seismic event, the operational downtime is limited to meet the resilience objectives of the owner.

A framework specific to a fire hazard to discuss in relation to vulnerable populations is A Framework for Fire in Informal Settlements. Informal settlements as defined by this framework are unplanned and often densely populated residential areas where inhabitants may lack security of tenure, have poor-quality housing, have both limited support infrastructure and service and have a high vulnerability to fires and other hazards. Informal settlements include slums, refugee camps and internally displaced persons’ camps.

There currently is limited information on construction guidance, enforcement and fire safety of informal settlements. These communities lack fire safety guidance, programming and resources. The framework structure is a holistic view of how to mitigate the risk of fire and reduce the impact to a vulnerable population, which needs to be analyzed within each local context.

The foundation of the framework is based on four components termed as the “disaster cycle”: mitigation, preparedness, response and recovery. For each part of the disaster cycle, there are three aspects that the hazard can be viewed in relation to: household/building, community and city. The disaster cycle is one way to view and consider vulnerability and resilience to a particular hazard. The components are defined in the framework:

Mitigation: Measures to prevent or reduce the likelihood, severity and consequences of fire.

Aspects: natural environment, built environment, causes and catalysts.

Preparedness: Strategies, procedure, resources and training that influence and inform stakeholders’ fire response and recovery.

Aspects: Organization and planning, awareness and training, fire safety resources.

Response: Actions taken during a fire incident to save lives and protect property and critical infrastructure.

Aspects: Communication, evacuation, firefighting.

Recovery: Actions taken in the aftermath of a fire incident, both immediately to assist with health care and welfare and longer term to return communities to normal life and bring about improvements in fire safety.

Aspects: Welfare and support, lessons learned, reconstruction.

While the Framework for Fire in Informal Settlements is specific to a single hazard and community and is intended to aid in the development of additional assessment tools, the methodology and structure is adaptable for other hazards and scales.

Creating resilience against nature

It is important to understand how the natural environment influences the design of buildings, communities and cities. Engineers should take into consideration that the most vulnerable populations may be living in areas that have high risk of experiencing devastating loss when exposed to shocks and prolonged stresses. While there are many dynamics that can attribute to a vulnerable population, the parallels to the framework will be made with populations that are socioeconomically disadvantaged.

Much like informal settlements, other socioeconomically disadvantaged neighborhoods may be disproportionality exposed to more shocks and stress and have less resources to aid in recovery. These include flood risk zones, very high fire severity risk zones and proximity to seismic faults lines. Buildings in these neighborhoods are likely to be older and unlikely to have been updated since they were first built, resulting in reduced construction safety measures applied in comparison to a newer building. Although the cause and catalysts may be the same experienced across a city, the impact experienced by these communities is typically more significant and the recovery process is much longer dependent on the resources available.

Like with any preparedness strategy, the results are only as beneficial as the applicability to the local context, community ownership with the recommended strategy, regulatory enforcement of the strategy and overall community and city planning. It is worth noting that regulatory enforcement is not applicable to informal settlements or homeless encampments. The access and availability to safety resources could be disproportionate between the economic profiles of the population and communities.

Response during a shock and stress is directly related to the preparedness and recovery of a community. If the community is very well prepared, has plans for specific shocks and stress, the population  is knowledgeable about the plan and implements the correct measures (communication, evacuation and public service response), then the impact to life safety would be reduced.

Alternatively, there is an increased risk to life safety when there is no clear plan, miscommunication, direct communication is untimely, the community is not aware of the plan or chooses not to follow the directives, there are insufficient evacuation routes or insufficient emergency vehicle access locations.

After any shock or prolonged stress, the recovery of the communities will differ. Dependent on the recovery plans created and funds available, assistance programs to provide mental and medical attention, water, food, sanitation facilities, shelter and legal support will differ based on the community’s available resources, the number of people affected and the estimated period of time to offer aid.

After the welfare and support is offered to the population, an assessment of response should be undertaken to understand what areas of the preparedness plan worked well, what areas need to be improved, as well as acknowledge any gaps that were seen that could be developed and implemented in a revised strategy. Should reconstruction of the building, community or city occur?

The lessons learned should be integrated with the new design as well as compliance with the applicable life safety measures in the codes and standards. The framework states, “Recovery is a dynamic process where the immediate needs of survivors must be balanced and aligned with long-term strategic objectives to build back better.” This recovery process is then directly linked to the mitigation process when design consideration is to build safer and more resiliently.

Figure 3: In commemoration of the 350-year anniversary of the Great Fire of London, a wooden model of 1666 London was created by burn artist David Best. Arup’s fire protection engineers were asked to complete a fire safety assessment, testing and advise on the risk to the audience, buildings and the environment. Courtesy: Christine Pongratz, Arup

Figure 3: In commemoration of the 350-year anniversary of the Great Fire of London, a wooden model of 1666 London was created by burn artist David Best. Arup’s fire protection engineers were asked to complete a fire safety assessment, testing and advise on the risk to the audience, buildings and the environment. Courtesy: Christine Pongratz, Arup

Future resilience plans

Consideration of the future is also imperative. With the staggering rate of technology innovation and product development, it is essential for designers, contractors and authorities having jurisdiction to understand the risks and limitations of new products and ensure that appropriate life and life safety measures are being taken for occupants within the building as well as first responders.

The codes and standards development may not keep up with the product development before clients want them to be incorporated into project. The implementation of these new products may improve the buildings resilience, but not at the expense of life safety. The designers need to consider the potential risks and provide sufficient safety measures to reduce the risk to life safety.

The future also will have a rapid population increase, with much of the population projected to be concentrated in cities, which may cause a decrease in affordable housing. This has the potential to cause an increase to the number of informal settlements and homeless encampments. In addition, climate change may bring  severe events more frequently. These factors should be considered by governments, owners, developers, designers, consultants and contractors as they consider future plans.

Designing for fire and life safety means complying with the building code and providing enough measures within the building and structure to safeguard the occupants until they can get out of the building to a determined location safely. There is a level of resilience incorporated into the design codes and standards based on historic fire incidents, however, if buildings, communities and cities want more robust, adaptive and integrated systems to operate during and after abrupt shocks and periods of stress, then a holistic view of resilience is required. Bespoke solutions maybe required to achieve the desired resilience for buildings and cities in unique locations, with unique contents and unique exposures to hazards.

There are frameworks and methodologies available to aid the dialogue between owners and government officials and designers and consultants to consider cascading hazards and create the right level of resilience and life safety for the local context.


Mackenzie Hill
Author Bio: Mackenzie Hill is a senior fire protection engineer at Arup. For the past nine years, she has been based in the U.S. and U.K., worked on projects around the world and is involved in many aspects of the built environment.