SUITLAND, Md. - As part of Executive Order 13123, Greening the Government Through Efficient Energy Management, which charges the federal government to promote energy efficiency in building design, construction, and operation, Select Energy Services Inc. (SESI), recently completed construction of a new 1,000-ton central cooling plant at the Washington National Records Center (WNRC). This project added new efficient chillers, cooling towers, pumps, and optimal controls to serve WNRC's cooling load. The work totaled $8.63 million in cost-effective measures and is expected to generate $1.11 million first-year savings. These savings should support the investment over a 15-year financing term.

SESI followed a design/build approach to accelerate the implementation and generate savings, which result from the greater efficiency, optimal control, and the reduction in the simultaneous overcooling/reheating that would result from the rebalancing of the existing stack air-handling units of the chiller plant, according to the company. "The new plant houses two premium-efficiency chillers that are driven by electric motors and variable-speed drives," said Wesley Burns, SESI project manager.

A pre-fabricated pump skid that incorporates variable-primary pumping and associated controls delivers the chilled water. All of the motors in the plant are high efficiency and are variable-speed-drive controlled. The distributed control system selects the proper combination of chillers, pumps, and tower fans, operating the plant as efficiently as possible.

"The new chiller plant is more adequately sized for the anticipated loads on the building and will operate more efficiently than the previous central plant equipment, particularly at part-load conditions," said Burns.

Publication date: 12/05/2005