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September 23, 2004
Photo courtesy of Sparling
Engineers used extra space between floors to make additional room for lighting controls, circuit panels and future panels.
Coordinating the building systems in the new U.S. Federal Courthouse required strong collaboration among electrical, mechanical and structural engineers.
Engineers tasked with fitting the building's "guts" into the most efficient footprint also faced challenges such as adhering to three sets of design criteria and facing heightened security for building and prisoner areas.
The trend that civic buildings be attractive and approachable yet invulnerable to internal power outages or terrorist threats has summoned all engineering disciplines to a more rigorous and collaborative design process.
E-mails and teleconferences may be the norm for some aspects of project coordination, but nothing beats meeting face to face.
Early in the project, electrical engineer Jim Duncan of Sparling, along with structural engineer Jon Magnusson of Magnusson Klemencic Associates and mechanical engineer Mark Leinenwever, promoted an engineering forum separate from the regular project meetings for electrical, structural and mechanical engineers. This kind of communication may seem like standard practice on projects of this magnitude, yet it was an innovation developed in tandem with the steel core structural system.
"The unique needs of each discipline created by the courtrooms, earthquakes, security and building height demanded the creation of a structure very different than anything that has been built before," said Brian Dickson, a structural engineer for Magnusson Klemencic Associates.
"It really took additional collaborative effort and invention for all the building systems to work so successfully."
For the electrical design it was critical to understand early on where power and telecommunication cabling could run to avoid the central core structural systems where these services are generally located. The engineering forum determined where electrical conduits, busways, cable trays and mechanical ducts would run relative to penetration of the structure. The team then reported its determinations to project architect NBBJ. This collaboration made a significant difference in achieving the overall project goals.
"Technology and building systems are changing at an incredible rate, requiring a new approach to engineering design," said NBBJ project manager Jim Tully.
"Flexible design and integration of electrical, mechanical and structural engineering allowed simultaneous coordination and quicker, more effective design decisions."
Other meetings between the subcontractors and design consultants were extremely helpful in clarifying issues during construction. Conflicts were discussed up front, not in the field.
Flexibility for the future
U.S. General Services Administration buildings such as the courthouse are designed to be flexible and easily reconfigured if space needs change.
Working from the GSA guidelines, electrical engineers met with each user group to define individual design criteria needs. Anything engineers could do to reduce the complexity or costs of equipment yet provide optimal building flexibility was a key objective. The priority for flexibility is reflected in the following:
Raised floor. A raised floor supports a flexible floor plan. The challenge was to specify a floor box module to fit a 6-inch floor space, meet the power and telecommunication needs of multiple tenants, and minimize the quantity and sizes of equipment by standardizing where possible.
Another challenge was to allocate space for an unknown quantity of telecommunication cables, which are generally not specified until later in the project. Collaborating with the other disciplines and building tenants, electrical engineers conducted research to provide a typical number of telecommunications pathways without knowing what the final requirements would be. The engineering forum was especially helpful in this regard since main corridor areas were spaces where every system needed to distribute services.
Keep AV spaces flexible. In the audiovisual world, courtroom presentation technologies are constantly improving. As a result, equipment requirements and cabling infrastructure are subject to frequent change.
Given the typical five-year cycle of many AV components, system design and equipment selected at the beginning of a project may be outdated at the time of procurement and installation.
On this project, the raised floor provides a flexible platform that allows the court's AV designer to change specifications and update systems to current equipment where desired. Local U.S. District Court architect Dennis Berhalter was instrumental in orchestrating the AV needs of building tenants, from getting the right players on board to making final decisions when interests conflicted.
"Keeping infrastructure flexible for AV systems is non-negotiable," said Berhalter.
"It was critical to ensure that the basic infrastructure incorporated all of the tenants' system pathway and interconnection requirements."
Future capacity. Much of the value of electrical design is in building capacity for future growth. Courthouse designers sought to provide adequate power system equipment sizing to accommodate future load increases or new equipment. Working closely with Seattle City Light, physical space was reserved for additional transformers should the owner require them.
Not surprisingly, continuity of service and coordination of all systems was a major concern. Collaboration among engineers was critical to satisfy code requirements yet avoid penetrations through the steel core.
To reduce the risk of power outages, four main switchboards serve the tower office spaces, including separate power for mechanical services. Ventilation equipment is located primarily in the penthouse area, and refrigeration equipment is located in the basement. The office power loads are split between the other two services.
If future maintenance or modification of the power system is required and the building manager needs to de-energize one side for service or changes, half (or more) of the building power will still be available. The busway distribution system was designed with wall separation between power risers to improve the safety and reliability of the main power distribution system.
All of the floors have either a computer/technical power source or a "normal" general-purpose power source. The transformers for the dual-power system were installed on alternating floors rather than on each floor to maximize space and control costs.
To meet tenant grounding requirements, equipment-bonding conductors were provided in all circuits not just where required by minimum code requirements to provide better electrical service without the expense of isolated ground conductors.
Electrical outlets are color-coded to help manage power sources and solve power system-related equipment disturbances.
Restrictions in the building footprint and programming for the courtroom floors required "vertical thinking" for placement of the typical floor distribution panels, transformers and related electrical systems equipment.
Few buildings this size have much, if any, extra height between floors due to significant costs associated with each added foot of height. In the courthouse, the floor height above the seventh floor is greater than in typical office high-rises due to the extra ceiling height required for the courtrooms.
Given the tight floor plan, electrical engineers used the extra floor-to-floor spacing for build "double-decker" mezzanine space above each floor's electrical room. This space accommodates lighting controls and branch circuit panels as well as future panels. All electrical and telecommunications rooms were stacked vertically. Choosing the right location for the stacked spaces required close coordination with the architect to maintain the GSA's and court's criteria for both initial and future equipment spaces and capacity.
As new construction continues to promote innovation, collaboration among engineers and architects will become even more critical.
"We are pleased not only with how this facility looks and feels to users and visitors, but how well it works," said GSA project manager Rick Thomas.
The new U.S. Courthouse shows how a meeting of engineering minds is the best way to solve multidimensional coordination issues and bring lasting value to a project.
John Parry led the electrical engineering design for the U.S. Courthouse and is an associate at Sparling, an electrical engineering and technology consulting firm with offices in Seattle and Portland.