BRAC 133—Washington Headquarters Services
New construction: BRAC 133—Washington Headquarters Services; Southland Industries
Location: Alexandria, Va.
Firm name: Southland Industries
Project type, building type: New construction, office
Project duration: 3 years
Project completion date: Aug. 9, 2011
Project budget for mechanical, electrical, plumbing, fire protection engineering only: $125 million
Southland Industries was the engineer of record and installing contractor for five trades: sheet metal, piping, plumbing, fire protection, and controls. As part of the BRAC program, the project was required to adhere to a strict, accelerated schedule set forth by BRAC guidelines. In addition, the project started approximately a year later than originally planed. Ultimately, the project was delivered 5 weeks ahead of schedule. Another challenge for the BRAC 133 design team was that the building request for proposal (RFP) indicated that ASHRAE 90.1, U.S. Green Building Council LEED Silver, and the Energy Policy Act of 2005 were part of the contract requirements. During design, the project team was able to exceed the minimum energy goals, which enabled the building to be awarded with LEED Gold certification. The magnitude, schedule, complexity, and scope of the project combined to create a challenging engineering project.
The BRAC 133 project in Alexandria, Va., is a 1.7 million-sq-ft office tower owned by the Department of Defense. Southland utilized its engineering ability to develop a system that consumed approximately 27.5% less energy than a similar building utilizing an ASHRAE 90.1 baseline model. The building utilizes an innovative fan-powered induction terminal unit (FPIU) system with outside air (OSA) provided by a dedicated outdoor air system (DOAS). The fan-powered induction unit is a modified series fan-powered variable air volume terminal unit equipped with a filter, primary (outside) air valve, supply air fan and electrically commutated motor (ECM), heating coil, and sensible only cooling coil. Dehumidified OSA is supplied to the zone for humidity and CO2 concentration control. Induced air is filtered and then cooled or heated through the use of a sensible only cooling coil, or heating hot water heating coil. Induced air is supplied to the space along with outdoor air to maintain the zone temperature, humidity, and CO2 level setpoints. The building is supplied with two chilled water-cooling loops. A 42 F (5.6 C) latent chilled water loop is utilized for dehumidification of outdoor air and cooling in zones where a high latent load is present. A 55 F (12.8 C) sensible chilled water loop is utilized to provide sensible only cooling to the fan-powered induction units and information technology (IT) loads. The use of the warmer, sensible chilled water loop yields significant increase in waterside economizer usage along with increased chiller efficiency. The net result is a high-efficiency cooling system that provides optimal occupant thermal comfort. Without Southland’s engineering and energy modeling capabilities, the BRAC 133 project would not have met its project goals.
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