What Is Resiliency?
Robert Grupe / December 2017
Q: Can you provide some clarification on the use of the term “resiliency” as it relates to building construction?
A: The term has been used in many ways and is currently in vogue. In psychology it defines the ability of the human spirit to overcome adversity. In nature it refers to the ability of a species to adapt to an evolving environment. Following that logic, for construction the term describes how a structure or a building material reacts to extreme conditions. What makes this relevant is that there is a general push to mandate provisions within building codes and standards that require new levels of resiliency in design and construction. The drivers behind this push are various agencies of the federal government, including the Federal Emergency Management Agency, the Department of Homeland Security and the National Institute of Building Sciences. FEMA has established what is termed a “MAT,” or Mitigation Assessment Team program. The goal is to increase the damage resistance of future building stock by forensic investigation of buildings impacted by natural and man-made disasters. From Hurricane Sandy to the Oklahoma bombings, FEMA experts have investigated structures and ultimately made recommendations for code changes that enhance building resiliency. Recent current events serve to underscore the importance of this line of thought.
A good source for information on the subject can be found in the document “High Performance Based Design for the Building Enclosure—A Resilience Application Project Report” published by Homeland Security and NIBS. To lay the foundation on resilience, the publication defines the term “attribute.” These attributes are performance-oriented objectives that a building should be designed to incorporate. The attributes are specified as safety, security, energy conservation, environment and durability.
Safety is the ability of a structure to withstand natural hazards. Hazards or events include fire, flood, seismic and wind. Security is resistance to man-made events such as blast and ballistics. Energy conservation focuses on how energy efficient a building is, and environment is how much the building components impact our environment. The final attribute is durability, and it can be seen as the structure’s ability to resist moisture migration and the debilitating effect of water intrusion.
To some extent resiliency is already embedded in existing standards, building codes and design practices. For example, the term “critical and essential buildings” represents certain types of buildings that must withstand and function in the aftermath of an earthquake. Hospitals, fire services and public safety fall into this category. Therefore, by code they are designed and constructed using a higher level of seismic restraint.
Recognizing that building codes must evolve with time; the model codes are on a three-year cycle. This means that every three years, a new version will be published. Changes to the code are done in an open, transparent method, and proposals to a code change are given within the three-year cycle. In this last cycle, many submitted changes were based on the concept of resilience. Most were defeated, but with the rise in the number of natural disasters, one can assume the proposals will return.
What does this mean for the contractor, and what may happen in the future? The good news is that many of the materials and assemblies used today can be argued to be resilient. Fire resistance is a core attribute in the systems that contractors currently install. Many of the materials are considered non-combustible, or at the very least can be used as an integral component in a fire-resistive assembly. Seismic, blast and even ballistic resistance can be designed into a system. This is supported by many of the tests completed to date. Highly thermal efficient systems can be designed and installed using existing technology and materials. Restricting moisture migration in an assembly is achieved through design and construction techniques.
The bad news falls into the category of perception. While existing data may support the resiliency of the materials and systems contractors typically use, they are not recognized as such. This means the argument may have to be made simply to thwart a system substitute. Architects may feel forced to use alternate design solutions to acquire resiliency.
Should the concept of resiliency gain momentum and become codified for the general building stock, there may be some changes that will naturally follow. Code change always fosters product and system innovation. The code requirement of an air barrier, for example, led to a new generation of products. The firestop industry emerged as a result of changes in the building code. This can lead to new opportunities and a broader scope of work for the contractor.
It’s too soon to say that the industry is headed to more resilient construction. Most of the proposed changes were voted down but may have a different result in the next cycle. However, the contractor should monitor the development of this trend. Based on the definition provided by NIBS, the systems installed today are elastic and to some degree already resilient.
Robert Grupe is AWCI’s director of technical services. Send your questions to email@example.com, or call him directly at (703) 538.1611.