Building Resiliency

Designing buildings to withstand natural and man-made disasters through product specification
 
Sponsored by Construction Specialties
By Rebecca A. Pinkus, MTPW, MA
 
1.25 AIA LU/HSW; 1 AIBD P-CE; 0.1 IACET CEU*; AAA 1 Structured Learning Hour; AANB 1 Hour of Core Learning; AAPEI 1 Structured Learning Hour; SAA 1 Hour of Core Learning; MAA 1 Structured Learning Hour; NSAA 1 Hour of Core Learning; OAA 1 Learning Hour; NLAA 1 Hour of Core Learning; NWTAA 1 Structured Learning Hour; This course can be self-reported to the AIBC, as per their CE Guidelines.

Learning Objectives:

  1. List key natural and man-made disasters that affect the built environment.
  2. Define resilient design and how it benefits cities, communities, and the economy.
  3. Discuss how designing for resiliency can impact building design and improve occupant health, safety, and well-being.
  4. Describe the benefits of specifying products designed for resiliency.
  5. Explain how buildings can achieve a U.S. Resiliency Council (USRC) rating.

This course is part of the Resiliency Academy

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Climate-Related Events

Wildfires, drought, and extreme heat and cold events are all climate related, and they have all become increasingly common and more severe.

Wildfires are the most destructive, with impacts that can range from burning or melting building components to completely destroying towns, as was the case with Paradise, California. In addition to the immediate loss of the built environment, fires can cause power surges from damaged power systems, smoke and soot damage, and soil erosion—the latter of which can put the area at risk for flooding and mudslides.

While wildfires can start in any number of ways, from a carelessly tossed cigarette to an errant ember from an unattended campsite, the key is that they spread quickly and can impact structures within the region, usually via embers and firebrands, such as burning brush or trees, that get carried on air currents and land on building exteriors, which then ignite. Sometimes the embers or firebrands can enter a structure, for example, through an open window, and ignite the building from the inside. Regardless of the mechanism, once a wildfire impacts the built environment, it tends to spread rapidly.

Other climate-related events include droughts as well as extreme heat and cold events, which can impact the built environment through power outages (both hot and cold extremes), loss of thermal comfort, and loss of water sources. Extreme heat events occur when the temperatures are 10 degrees or more than the average high temperature and remain high for several weeks. Such events can trigger droughts, which have a cascading effect in communities, especially those with businesses that rely on agriculture.

Extreme cold events, such as polar vortexes, occur when the temperatures are at or below freezing for an unusually long period of time; for example, for several weeks. Sometimes, but not always, these cold events coincide with severe winter storms, which can knock out power supplies and leave buildings vulnerable to cold-related damage, such as burst pipes.

Geologic/Seismic Disasters

Finally, geologic and seismic disasters, such as landslides, mudslides, and earthquakes, can take a huge toll on the built environment.

Landslides and mudslides can both damage buildings caught in their paths. While similar in the sense that both are typically initiated by heavy rainfall in hilly regions where the soil cannot absorb the water and erosion has already occurred, the two differ. Landslides refer to the movement of earth and rock and occur on steep slopes, which crumble when the soil is destabilized. Mudslides, on the other hand, occur when an inundation causes groundwater to rise and the soil to lose friction. In either case, buildings can either be damaged as the moving earth impacts the building or as the soil beneath the building moves and shifts.

Earthquakes are another concern. The primary damage of earthquakes comes from ground shaking, with many different factors contributing to the damage, such as the strength and magnitude of the quake, how close a structure is to the fault, the local geology, and even the soil type. Ground shaking impacts buildings by moving them both laterally and vertically, both of which can cause the structure to fail from excessive deflection and deformation. In addition, earthquakes can often cause the ground to behave in ways that damage buildings situated on top of the zone. Given that buildings rely on a level, stable foundation, when the ground under them rapidly expands, or when the ground ruptures or the soil liquefies with a swell of groundwater or even suddenly sinks (subsidence), buildings can suffer.

In some regions, earthquakes are followed by tsunamis and flooding, and in other cases, the buildings may also be impacted by fires.

Current building codes for seismic resilience are designed to protect lives by specifying that buildings stay intact long enough for occupants to safely escape. In the event of a major seismic event, however, buildings may be damaged to such an extent that they are no longer safe for future use.

Man-Made Disasters

Natural disasters are not the only forces threatening buildings. Certain structures, particularly industrial sites, are also at risk of being damaged by man-made disasters, such as explosions. Facilities that produce or use combustible materials are especially at risk, and an explosion inside an industrial site can damage the building itself, all while putting the building occupants at great risk.

Regardless of the type of disaster, most also have cascading effects, whether they include fires after an earthquake, or power outages and infrastructure damage after a hurricane, ice storm, or blizzard. Such secondary effects only prolong the time it takes for a community to recover and rebuild. In terms of commercial spaces, this means businesses may be closed for longer, incurring yet another level of financial damage that may take months to recoup, if they manage to reopen at all. In the next section, we will look more in depth at the human and economic costs of natural disasters and, to a lesser extent, man-made disasters.

Resilient Design and How It Benefits Cities and Communities

Natural and man-made disasters happen. And we’ve seen that, at least in the case of natural disasters such as storms, floods, and wildfires, they are happening more often, and the damage is increasingly severe. Communities affected by natural disasters may suffer on a personal level from loss of life and property as well as income if businesses were affected. Depending on the disaster, roadways in and out of towns may be closed, disrupting the supply of goods and services, which can impact businesses lucky enough to avoid building damage. And the longer a business is out of service, the more likely it is to lose customers.

According to global insurance statistics, 40 percent of small businesses fail to reopen after they are affected by natural disasters simply because they cannot afford to repair the buildings. Moreover, 25 percent of the businesses that do reopen tend to fail within the year as long as they weren’t impacted for longer than five days; the longer they were impacted, the less likely they are to succeed. The U.S. Small Business Administration notes that up to 90 percent of businesses that were closed for five days or more are likely to fail within the first year of opening, and 75 percent close their doors within two years.5

But small businesses aren’t the only buildings to be affected when disaster strikes. Other commercial structures, such as office spaces, sports complexes, and aviation and transportation complexes can all impact the daily life of the community if they are out of commission. Even more critical are public structures such as schools, libraries, first-responder stations, jails, hospitals, and senior-care facilities, all of which provide critical services, especially in times of need. When such structures are not able to meet the needs of the community, other buildings must be able to pick up the slack. Hurricane Katrina comes to mind, for example, where the Superdome in New Orleans was used as a makeshift shelter for people who had to evacuate their homes. When conditions there became unmanageable, people were bussed to the Houston Astrodome, which housed nearly 25,000 hurricane victims.

Again, Hurricane Katrina serves as a good example of the problems that can arise with the cascading impacts from a natural disaster. In this case, hospitals were critical during and after the storm, and for the most part, many only suffered superficial damage from the storm. However, the cascading impacts on the infrastructure meant that, like many other buildings in the city, they had to be evacuated because of loss of power, water, and sewage services. In the days following the storm, 11 area hospitals were inaccessible because of the floodwaters, with a total of 1,749 patients in care. Because of the nature of the disaster, the hospitals also took in people who left their homes; the Louisiana Hospital Association (LHA) estimates that the hospitals housed more than 7,600 people in addition to the patients during the immediate aftermath of the storm.6

Examples such as Katrina show the extremes, but in the almost decade and a half since the hurricane, we have seen so many different versions of the extremes, whether through storms, fires, floods, or other disasters. Each time, vulnerable structures fail, citizens are displaced, and buildings that can withstand the disaster shelter those in need.

This brings us to the heart of resilient design: buildings designed to withstand weather extremes, seismic forces, or the impacts of natural and man-made disasters tend to do their job and do it well. Resilient design is an opportunity for developers, architects, and engineers to engage in measures that can protect lives and property, extend the lifespan of buildings, reduce the number and amount of post-disaster repair costs, and lessen the down-time before buildings can return to their necessary function.

Resilient Design: What It Is and Why It Matters

To fully understand resilient design, it’s important to understand what we mean when we talk about “resilience” in the building profession. According to the Resilient Design Institute, resilience is “the capacity to adapt to changing conditions and to maintain or regain functionality and vitality in the face of stress or disturbance. It is the capacity to bounce back after disturbance or interruption.”7 If we go back to the list of natural disasters and various secondary impacts discussed in the previous section, we see that this definition covers not only the built environment but also the surrounding communities and infrastructure. How long does it take for a town hit by a tornado, or a hurricane and flood, or a wildfire, to recover and get back to regular daily life? A built environment that is not resilient can take a long time to recover; however, a place that is resilient may suffer less damage and therefore be able to bounce back more quickly.

With that in mind, resilient design refers to buildings, landscapes, communities—and even regions—that are deliberately designed to withstand impacts that might otherwise damage or destroy the community. As with many health, safety, and welfare decisions, resilient design stems from seeing how vulnerable buildings and communities have fared in different disaster situations and turning those lessons into practical solutions.

Often, communities greatly affected by natural disasters shift their priorities to resilient design. Buildings in seismically active areas, for example, may be constructed to sway when the ground shifts or be built from materials that resist the secondary issue of fires. The same goes for areas that are often in the path of hurricanes or other severe storms, with design focusing on mitigating water intrusion and wind damage.

Resilient design relies on three key factors: hazard mitigation, passive survivability, and adaptation. Combined, these factors can help buildings, and thus communities, become more resilient against the impacts of natural and man-made disasters. Buildings and communities designed with resilient practices and materials can also be protected against the financial costs of damage, and thus play a role in benefitting the local and broader economy as well.

The Federal Emergency Management Agency (FEMA) defines hazard mitigation as “any action taken to reduce or eliminate long-term risks to people and property from natural disasters.”8 By extension, hazard-mitigation planning is “a process used by state, tribal, and local governments to identify risks and vulnerabilities associated with natural disasters and develop mitigation strategies to reduce or eliminate long-term risks.”9 Mitigation planning measures tend to stem from previous disasters and the lessons learned—and in terms of the built environment, those lessons are incorporated into newer versions of building codes. New lessons are being learned every time a new disaster happens, and mitigation strategies continue to improve. As a result, new structures often take into account factors such as roofs designed in shapes that have high-wind tolerance, rainwater management from roof run-off, or even slab-on-grade construction that eliminates basements (prone to flooding) in the first place.

As a way of keeping first responders and building professionals up to date, FEMA provides extensive programming and resources that address issues concerning communities as well as individual building strategies, available at www.fema.gov/hazard-mitigation-planning.

Passive survivability refers to a building’s ability to maintain the basic functions critical to keeping occupants safe and comfortable, specifically when power, heating, and/or water are lost for an extended time. Often, schools, hospitals, and civic buildings are designed with more passive survivability features than the average residential house, and as such they are often used as emergency shelters during disasters.

Adaptation in terms of building design considers mitigation over time, and the assumed changes and evolution of both building design and community responses. Buildings can be designed to include adaptive strategies that anticipate impacts of future natural disasters.

Resilient building design benefits cities, communities, and the economy by protecting lives and property, extending the lifespan of buildings, reducing the number and cost of post-disaster repairs, and minimizing building downtime.

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Originally published in Architectural Record

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