A Balancing Act at Miami Federal Courthouse

It seems that successful design often requires balancing competing priorities. The new Miami Federal Courthouse, a collaborative project of HOK and Arquitectonica, is no exception. The General Services Administration, in conjunction with the Department of Energy, is imposing stringent energy goals for all new Federal Courthouses. Based on several runs of the Life Cycle Cost Analysis (LCCA), the design team had met the BECON goal of 550 MJ/SM at the end of the Design Development phase.

As the team proceeded into the Construction Documents phase, further analysis of the 9/16-inch laminated glazing revealed that the actual U-value for the glazing was 1.12, as opposed to the value of 0.69 required to meet energy goals. The glazing is required to meet the large missile requirement of the Florida Building Code for hurricane design. The design team had utilized the material throughout the building to maintain a consistent aesthetic appearance. Another design challenge has been meeting the blast criteria for the project. The 9/16-inch laminated glazing proved to be so strong that it was imposing blast loads exceeding 850 PSF on the framing members of the curtain wall system.

The team’s design solution involved utilizing laminated-insulated glazing within the small missile zones of the building to meet the requirements for hurricane design. The 9/16-inch laminated glazing will be installed at the lower level Atrium Lobby, which is shaded from the South Florida sun by a perimeter colonnade. The U-value for the new glazing type is 0.34, which exceeds the DOE requirement. Additionally, the material meets the blast criteria and reduces the pressures on the curtain wall framing system.

The increased performance of the glazing allowed the team to reduce the size of the chillers, pumps and cooling towers, offsetting the first cost of the glazing. As a result, not only will the new building meet the energy goals, hurricane requirements and blast criteria; but it also will exceed the energy goals and prove to be more energy efficient from a life cycle cost perspective. The new project is slated to begin construction in July 2002.

Contact Tim Blair, HOK Florida