Click HERE for the Article Out Loud
There is a need for more resilience as it applies to emergency preparedness in the design, construction, and renovation of the built environment. Conventional design of buildings by architects and engineers meets code and aligns with the owner’s or developer’s programmatic requirements. However, unless the program specifically calls for safety, security, or environmentally resilient design, these elements are not usually included as a focus in the design. This does not mean that traditionally designed buildings are not safe or cannot withstand the effects of weather or seismic instability. Given that architects and engineers are professionally responsible for the health, safety, and welfare of the general public, they are required to produce buildings that meet code. However, the current conventional design of a code-compliant commercial structure does not always require additional thought to potential threats outside the envelope of the building. Put another way, a building will be accepted as a successful building and will likely serve the owner as a good investment if it:
Keeps the occupants cool in the summer,
Keeps the occupants warm in the winter,
Meets all required structural and energy codes,
Has a properly designed exterior that keeps out the regionally appropriate weather, and
Meets the owner’s aesthetic and programmatic requirements.
This process can be improved by including an all-hazards approach to building design that considers not only the function of the building during normal operation but also the safety of the occupants and the surrounding community by considering the possible threats to the building from any regionally specific threats.
All-Hazards Design Process
The most important step in an all-hazards approach for a resilient facility is to consult the area's Threat and Hazard Identification and Risk Assessment (THIRA). This resource should identify all known and possible threats to consider during design. Consult the Homeland Security Comprehensive Preparedness Guide (CPG) 201 for details on the THIRA and related information. Once the threats and hazards are identified, a stakeholder group should be assembled to include all relevant parties from the owner’s team as well as local providers such as fire, law enforcement, emergency medical services, emergency management, utility providers, and if relevant, outside agencies. By utilizing an integrated team at the outset of the design process, gaps in planning can be avoided that, if not identified, could produce catastrophic results.
Acknowledging that financial pressure is always a concern in decision-making, there must be a method to prioritize the threats and the appropriate response in design and construction. These threats are typically represented in a risk matrix from low-impact/low-frequency to high-impact/high-frequency. For example, a building designed for the Gulf Coast might classify a hurricane as a high-impact/medium-frequency event. In contrast, a nuclear power plant might classify a meltdown as a high-impact/low-frequency event. Both conditions require appropriate planning to mitigate potential impact but having the impact/frequency matrix allows for thoughtful prioritization of risk and allocation of resources.
“By utilizing an integrated team at the outset of the design process, gaps in planning can be avoided that, if not identified, could produce catastrophic results.”
Codes and Prescriptive Design
Although building codes have progressed a long way since their inception, they are, by nature, a retroactive measure. Building codes, historically, have been enacted in response to a failure. They have not been universally proactive despite calls for various restrictions to be put in place. Since building codes are part of a municipality’s jurisdictional power and are not arbitrarily applied, there may be resistance to adopting a code that could place unnecessary financial hardship on public or private development.
An example of a new code enhancement is the requirement in recent building codes for a storm shelter in K-12 schools or similar functions. The shelter must safely hold the entire building population for a duration outlined in the code (such as 90 minutes for a tornadic event). However, a similarly vulnerable population, such as sleeping students in university residence halls, does not have the same code requirement and could potentially be viewed as a financial hardship for some owners.
The approach to this, primarily relating to safety and security, is known as Crime Prevention Through Environmental Design (CPTED). The tactics and techniques of CPTED are beyond the scope of this article, but the four primary principles of CPTED are:
Natural Surveillance – allows for visibility by legitimate occupants to their surroundings;
Natural Access Control – access onto the property;
Territorial Reinforcement – identifiable features to clearly designate property boundaries; and
Management and Maintenance – upkeep of the property to demonstrate diligent ownership.
These principles are intended to inform the design and construction of buildings in a way that creates safe spaces. Critical attention must be given to avoid creating fortress-like buildings that are visually unappealing and uncomfortable to occupy. This same advice applies to buildings that are resilient to disaster.
Another concept from security design that applies equally to facility resilience is the principle of concentric layers of protection. Like when resisting criminal intrusion, multiple layers of damage can be inflicted by human-caused or natural disasters. The analogy of an onion is often used to describe this concept. By placing multiple layers of protection around sensitive or critical areas, these areas are shielded from threats. In relation to weather, this applies to building materials and construction methods to create sheltered spaces within these facilities. Having multiple layers eliminates the need to depend on one layer to provide total security because there is a redundant layer in case the outer layer is compromised. Suppose the design or programmatic requirement demands the reduced effectiveness of one of these layers (such as an all-glass wall looking into a large assembly space instead of a solid wall). In that case, the other combined layers of security must compensate for this shortfall to provide the same net level of protection to the occupants.
Practical Approach to Operation
Even the most effective design process in the world cannot overcome the element of human error. Daily operations of a facility must be considered to produce a facility that can be effectively and efficiently maintained in the manner intended. An example relating to school security might be the placement and operation of exterior doors relative to the HVAC system. If a building is not designed for proper humidity and temperature control, daily users are likely to prop open a door to get fresh air, thereby producing a serious security vulnerability. In the case of emergency management of a building, numerous quality-of-life considerations must be considered for both operation and process. The following is an abbreviated list of examples:
Establish familiar relationships with all local emergency service providers and allow them to tour the facility regularly to maintain familiarity.
Consider a comprehensive building identification system that provides exterior signage identifying window and door locations. These should use reflective letters of sufficient height to be seen by emergency vehicles responding to the facility.
Provide multiple locations to shut down outdoor air intakes and ventilation dampers if the THIRA shows proximity to possible sources of chemical risk like highway, rail, or industrial plant use.
Locate outdoor air intakes out of reach of unauthorized personnel to avoid introducing toxic substances into the airstream. A rooftop location is preferred.
Locate emergency generators, if they are part of the program, at least 25 feet from the building, parking lots, or any occupied structure. If generators cannot be separated from the public in this way, an explosion-proof enclosure may be utilized. These types of enclosures must not allow unauthorized personnel to enter them or hide contraband out of sight within the enclosure.
Ensure that appropriate public address capability is provided throughout the facility to complement the fire alarm system. If possible, consider multiple means of mass communication for all facility and grounds occupants, regardless of whether they are assigned users. Geofencing for emergency SMS messaging may be considered.
Ensure that the facility has adequate shelter-in-place capacity for the maximum occupant capacity. The event duration must be identified and considered when determining the space needed. For example, standing room is sufficient for most emergencies, but shelter-in-place for longer-duration events such as a hurricane may demand more square footage.
Identify if the facility needs backup power to maintain functional operation. A warehouse has very different power requirements than a hospital, for example.
Conduct proactive maintenance and functional checks of all critical systems.
Blast Resistive Design Strategies
Although blast damage would typically be seen as a high-impact/low-frequency event, some building uses may make them a credible target for terrorist activity. If so, the Federal Emergency Management Agency’s Risk Management Series Primer for Design of Commercial Buildings to Mitigate Terrorist Attacks (FEMA 427) should be consulted for detailed considerations of blast resistive design strategies. The exterior shape of the building can have significant effects on the ability to withstand explosive forces as well as high winds and airborne projectiles. Whenever possible, locate buildings with a setback from uncontrolled vehicle thoroughfares to minimize risk from vehicle ingress.
Although descriptions of the above concepts and strategies for an all-hazards design process are not an exhaustive coverage of the topic, they illustrate the strategic view necessary to produce more resilient facilities.