Kevin Ian Schmidt

At its most basic, layered security refers to concentric rings of site and building security. These rings typically progress from the exterior boundaries of a site to the exterior building shell to increasingly secure areas within the building. The rings are not always symmetric or well defined, but each one represents an increase in security hardening against external threats as one moves inward from the site boundary or building exterior.

In a layering approach, design consideration must be given to the flow of people and material as they move though public, private and restricted building areas. Controlled paths need to be established in conjunction with each layer of security. This is where design with security concerns in mind can minimize implementation and future operating costs.

Equally important are the internal security layering requirements that segregate building spaces from one another — a key requirement when multiple tenants or departments with differing security needs occupy a single building.

Securing Core Areas

Most buildings share core areas that include vertical transportation, electrical and telephone rooms, janitor closets, and public amenities like parking areas, lobbies and toilet facilities. A successful security design must not only plan for the flow of people and material during occupied and unoccupied hours, but also consider how this flow affects the sharing of public and service areas.

For example, building access from surface or underground parking facilities needs to be segregated and directed to a common access control point to minimize security staffing and other operating costs. Because of past incidents in high-profile buildings, underground parking may in the future be limited or not be provided at all.

When designing security to maintain segregation of building areas, life safety code requirements must be observed, and the required emergency egress paths must be maintained using appropriate egress hardware. Though it sounds simple, this is one of the most difficult requirements to implement because it requires comprehensive understanding and interpretation of building codes and close coordination of door hardware, security system and fire alarm system requirements.

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Design Principles for Security

Proper design and use of the built environment can assist in effective security layering. The following four design principles are key:

1. Natural surveillance: The ability to keep potential threats easily observable in parking areas and building entrances.
2. Territorial reinforcement: Defining private and public areas in the facility or campus using landscape plantings, pavement designs, gates and fences
3. Natural access control: Design of streets, sidewalks and building entrances to indicate clearly the public access routes and to discourage pathways outside the secure areas, using structural elements to complement electronic access control.
4. Target hardening: Design using features that prohibit entry or access, such as window, door and air intake location; locks; dead bolts; electronic card access; and closed circuit television (CCTV).

To enhance security, building exteriors will in the future likely be designed with fewer windows and other openings; exterior windows and doors at the lower floors will be reinforced. Fresh air intakes will no longer be at grade. The number of outside entrances for pedestrians on foot or from parking areas will be reduced to channel the flow to lobby security stations that can be staffed with the minimum number of personnel.

Underground parking, loading docks and service entrances will be located and designed to segregate and effectively control the flow of personnel and goods using transition areas. Building service areas, toilet facilities, corridors, and electrical and telecommunication closets will be located so that the building’s net usable space can be subdivided, segregated and secured as needed to meet the requirements for each tenant or department’s security, while maintaining the code-required means of egress.

Technology’s Role in Layered Security

In addition to physical barriers, a layered approach to security typically requires electronic security systems — different combinations of things like badges, biometrics, card access, door alarms, CCTV and package scanning machines in different combinations — along with personnel trained to make the final decisions. The effective placement of these systems can reduce staffing requirements.

The upper box on page 53 shows the placement of card access devices and personnel to control access to building core areas from the outside while minimizing staff needed to handle visitors.

In the example shown, everyone who wants access to non-public areas of the building is directed to the turnstiles that control access to the elevators. Visitors can gain access when authorized by the security personnel.

In a building similar to the one in the example, delivery trucks could gain access to the loading dock after being cleared by the security staff. Depending on the security level required, access to the freight elevators can be further controlled after inspection of the cargo.

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Further security layering can be implemented for personnel and material that have been cleared for access to tenant spaces. The bottom box on page 53 shows a typical arrangement of multiple-tenant floors. Tenant security is maintained with the use of card readers to control access into the space. Tenants that need to track personnel who enter and leave their spaces can use their own card readers. Tenant personnel can gain access to the toilet facilities while maintaining security; the use of keys or card readers at the toilet facilities is an option that needs to be evaluated separately. Those making deliveries from the freight elevator need to request access to tenant spaces via telephone or intercom.

CCTV systems with motion detection can provide continuous monitoring that is useful not only to grant access to the protected spaces, but also to provide forensic evidence needed to investigate security-related incidents. Digital CCTV provides for easy retrieval of information on demand without the time-consuming searching required by older analog systems.

Although security layering is a valuable strategy for controlling the flow of people and materials within the building, it isn’t the whole story. Operational plans are needed to limit access only to suppliers and staff with legitimate need. Deliveries of supplies from known sources should be coordinated in advance. Delivery times may have to be restricted to off-peak hours to avoid unnecessary delays to building occupants. For particularly sensitive areas, requirements for background investigations of outside contractor staff may need to be established to prevent “Trojan horses,” such as bugging devices, from being introduced into the building during construction, maintenance or deliveries. Emergency plans need to be developed and tested with the building occupants to address different types of security-related emergencies. Exit and emergency pathways need to be established for different scenarios.

Special measures and additional staffing may be required for special events, such as social functions and tenant relocations, where a large number of strangers may require access to secured areas.

In new buildings, security layering can be integrated into the original design in a very cost-effective manner. But, of course, occupants of existing buildings are demanding increased security as well. In most of these buildings, security improvements are more costly to provide because of significant additional staffing costs or building modification costs to redirect the flow of people and materials. Many existing buildings were designed with multiple entrance pathways; these buildings must add significant security staff or make costly changes to the building itself to provide minimum levels of security. Building owners will have to treat those additional expenses as a cost of doing business; tenants are demanding increased security, and those measures carry additional costs. Another challenge for existing buildings is that the security layering approach requires both building owners and tenants to accept changes in behavior without developing a trench mentality.

When it comes to upgrading security from what was acceptable in the past, there is no free lunch. To put it another way, no pain, no gain.

With new buildings, costs can be minimized. Doing that requires building owners to remember two key points: first, that during the design process it is never too early to plan for security; second, that many tools are available to provide security. And it’s not just building owners who need to think in a new way about security in new buildings. The increased demand for security also will require a change in the mindset of architects and engineers. Design professionals will have to consider how to incorporate into building designs the sometimes conflicting desires and requirements of building owners, occupants, vendors, visitors and governing agencies.

If everyone on the design and construction team focuses on security early and consistently, security does not need to be expensive and in many cases can be incorporated with minimal impact on the tenants who spend a great deal of their everyday lives in the building.

It’s also important to remember that effective security requires the building owner to address both operational and security technology issues as well as architectural factors. For example, it is critical that the issues of security staffing and training be addressed. With solid planning and an awareness of the tools available to designers, building owners can achieve the security levels they need without high ongoing costs.