District Department of Transportation

Existing building retrofit: District Department of Transportation; GPI/Greenman-Pedersen Inc.

Source: GPI/Greenman-Pedersen Inc.

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Project name: District Department of Transportation

Location: Washington, D.C.

Firm name: GPI/Greenman-Pedersen Inc.

Project type, building type: Existing building retrofit, office

Project duration: 1 year

Project completion date: Sept. 29, 2007

Project budget for mechanical, electrical, plumbing, fire protection engineering only: $4.2 million

Engineering challenges

The project wanted to achieve U.S. Green Building Council LEED Silver certification, which required reduction of lighting energy consumption by 15% below the ASHRAE 90.1 2007 baseline.

Solutions

The lighting strategy used was to design the general ambient level to a maintained foot-candle average of approximately 30 foot-candles and provide LED task lights to raise foot-candle levels to 50 foot-candles per IES recommendations. LED exit signs specified further reduced energy consumption. Occupancy controls were used to control lighting throughout the space and reduce energy consumption. Wall-mounted infrared sensors controlled smaller enclosed spaces; ceiling-mounted ultrasonic sensors controlled corridors and open office spaces; ceiling-mounted dual-technology sensors (infrared and ultrasonic) controlled conference rooms; and wall-mounted dual relay infrared sensors controlled small conference rooms. All occupancy sensors were provided with either integral or external override off switches to allow users to turn off lights even when the room was occupied to improve energy savings. The project was awarded LEED ID+C Silver Certification.