A Court with Appeal
The United States Courthouse and Federal Building in Central Islip, Long Island, NY, was envisioned as a departure from the traditional, monolithic look often associated with courthouse architecture. The design of the 822,000-sq-ft structure, by Richard Meier & Partners (New York) and The Spector Group (New York), was intended to break with tradition and create the feeling of awe expected of a courthouse through size, openness, and the generous use of natural light.
As part of the team that turned the design into reality, Syska & Hennessey's New York office played an important role in developing mechanical-electrical-plumbing (MEP) solutions that would satisfy functional requirements while maintaining the integrity of the architect's vision.
From the beginning of the project, the mechanical-electrical engineers were faced with challenges that had to be addressed within the parameters of the building's design and function.
To overcome these challenges effectively, the MEP systems had to be carefully researched, developed, and designed to provide energy-efficient and user-friendly solutions that would suit the building's dimensions and its architectural detailing. In addition, each system had to be equipped with the flexibility to accommodate a phased occupancy plan that calls for replacing office space with additional courtrooms over a 20-yr period. The structure was designed to house 23 courtrooms and 25 judges' chambers at the outset and as many as 39 courtrooms and 42 judges' chambers as demand increases. In the interim, the space will be occupied by other federal agencies.
The building's hvac requirements proved to be the most complex aspects of the project since they were affected not only by the phased occupancy plan, but also by the physical nature of the structure itself. Electrical and life safety systems also provided opportunities for ingenuity in design.
Glass Curtain Wall ExpanseTo create the open and inviting atmosphere that was sought for, the architect designed a 600-ft-long, 235-ft-high glass curtain wall across the south face of the building that allows for the entry of natural light and offers a view of the wide corridors and spacious waiting areas within. However, due to the insulating properties of the glass, the curtain wall also provide the potential for the interior waiting areas to become giant sweltering heat traps. It was assumed that greater cooling capacity would be needed to combat this effect, which would increase the building's utility costs.
The mechanical-electrical team developed several computer models to study the cycle of the sun, its intensity, and the resulting impact on the waiting areas. After careful evaluation of the data collected, the team recommended the installation of a "sunshade" across the glass facade that would allow an ample amount of light to enter while at the same time reducing the buildup of heat by deflecting a certain amount of the direct sunlight.
Working closely with the architect, the engineers devised a grid-like aluminum sunshade that minimizes the heat while melding seamlessly with the design of the facade, which incorporates aluminum along with the glass. The sunscreen, which extends 2 ft, 6 in. from the building wall, allowed the architect to maintain his aesthetic concept while preventing the heat trap effect and reducing cooling costs.
To further ensure a comfortable indoor environment, fan-powered boxes with linear diffusers were also installed along the perimeter of the facade at each floor to provide heating and cooling to the open areas. The boxes take the primary air from the central a/c units and mix it with return air from the ceiling plenum.
This solution was selected to maintain optimum heating and cooling conditions in the controlled climate of the spacious waiting areas. For both energy efficiencies and comfort, each fan-powered and variable-air volume (vav) box is controlled through the building management system.
Low-Temperature Air SystemUnique to the hvac design is the use of a low-temperature air system to provide the primary air handling for the building. The air temperature leaving off the coil of the system is 44 degrees F, which decreases the amount of air needed and allows the sizes of the ductwork and the vav boxes to be reduced. After a close examination of a life cycle cost analysis and the structural and building constraints, it was determined that this type of system was ideally suited to the building's air-handling needs.
The unusual floor-to-floor heights within the structure made the ductwork somewhat problematic. Because federal guidelines mandate a minimum 16-ft height in district courts, there is a floor-to-ceiling height of 19 ft on the fourth through the tenth floors where the courtrooms are situated. Thus, the 11-story structure is 230 ft tall, the equivalent of a conventional 20-story building.
Furthermore, there was scant space above the ceilings for the mechanical-electrical (M-E) systems, so the project's technical architect specified many penetrations in the steel in order to install the pipes and ductwork. Being able to reduce the dimensions of the ducts and vav boxes was thus particularly advantageous and shaved approximately $1 million off the construction cost of the project.
Additional elements of the courthouse's hvac system include six vav-handling units, ranging from 90,000 to 130,000 cfm, located in the penthouse level and providing service to floors four through 11. Each unit consists of two supply fans of 65,000 cfm each under a single casing, ensuring that at least a partial load can be provided should one of the fans fail. The units also make use of airside economizers and variable-frequency drives (vfd's).
In order to cool the building, three 830-ton electric centrifugal chillers were brought in to meet the primary cooling requirements, and one 300-ton electric centrifugal chiller to be used during off-peak, low-load periods. A plate heat exchanger was also installed to provide free cooling, and the condenser-water riser was fitted with capped valves at each floor as a contingency for future load increases.
63 Yards Of AtriumAnother arresting feature of the architectural design is a 190-ft-tall cylindrical structure on the southern facade that serves as the entrance to the building and leads into an airy atrium of the same height. For the rotunda, supply air was provided through the floor at the perimeter. Two supply fans were located in the basement and six smoke exhaust fans on the roof.
The rotunda system uses portions of the central hvac systems designed to shut down automatically in case of smoke. The system has an automatic and a manual override start/stop capability to exhaust the rotunda atrium and provide makeup air at the same time.
With all this equipment working diligently away to provide inviting conditions for those occupying the building, noise ultimately became an issue. A courtroom is a solemn place whose function is to dispense justice. The participants in a legal proceeding must be focused and alert, not distracted by the sounds of the hvac system.
To ensure that this would never occur, the M-E team designed the system with controls that are responsive to changes in occupancy and loads, and made extensive use of sound traps, sound linings in ductwork, and vibration isolators, all designed to reduce sound transmission to a negligible level.
The location and size (a maximum 2,000 cfm) of each fan-powered and vav box was chosen to meet acoustical criteria that specified different sound pressure levels in all eight octave bands for the different areas of the building, in conformance to the following requirements:
- Judges' chambers: NC-35;
- Courtrooms: NC-35;
- Conference rooms: NC-30;
- Jury assembly rooms: NC-40;
- Auditorium: NC-30;
- Press room: NC-40;
- Open plan office area: NC-40;
- Private offices: NC-35;
- Court support: NC-35/40; and
- Lobbies and corridors: NC-40.
Life Safety DesignLife safety was also a primary concern for the United States General Services Administration, the owner of the building, and the various federal tenants. To ensure the effectiveness of the sprinkler system, for example, two separate risers feed each loop in the system. In some cases, extended coverage heads were used. To augment the sprinkler system, stair pressurization and smoke purge systems were also installed. For added safety, the courthouse's security and door control system was coordinated and tied into the addressable fire alarm system.
This system incorporates state-of-the-art technology for point annunciation of addressable initiating devices. The design and location of the fire alarm data gathering panels and cable risers were planned so that modifications could be made with minimal disruption when the space conversions take place.
Taking into consideration potential emergency situations, two 1,250-kW emergency generators are housed in the penthouse to provide support for lighting, alarm systems, elevators, and other life safety systems, should the need arise.
The design phase of the project was completed and ground was broken in 1996. The $200 million federal justice center opened for business in June 2000 and was officially dedicated on October 16, 2000. ES