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ENERGY STAR Labeled Building Profile

1899 L Street
1899 L St, NW
Washington, DC 20036
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1899 L Street is a 12-story, class B office building located in the heart of the central business district (CBD) in Washington, D.C. The 198,831-square-foot building consists of offices, street level retail spaces, and an underground garage and was constructed in 1978.


Transwestern began managing 1899 L Street in November of 2004. At that time, 1899 L Street was suffering from deferred maintenance, and the building equipment was original. The building had an energy performance score below 50 on EPA's Energy Performance Scale.


The Transwestern team quickly developed a plan to address the building's equipment deficiencies. Some of the items included were:
The main cooling tower was replaced in early 2005, including variable frequency drives (VFDs) on the two fan motors.
The two Trane centrifugal chillers, a 400 ton unit and a 320 ton unit built in 1995, were overhauled in 2006 and 2007.
-- A VFD was installed on the retail condenser water cooling tower.
The supply fan and return fan motors on one of the two main air handling units that serves the building were replaced with high efficiency motors.


The Transwestern team made it a priority to familiarize themselves with the design of the building's HVAC plant and the operation of the energy management system. Soon thereafter, they discovered that some equipment was not operating as designed and other equipment was not even controlled at all. This presented some unique challenges in providing a comfortable working environment while at the same time conserving energy.


Two air handling units (AHUs) serve the majority of the building. The interior AHU supplies the core of the building with conditioned air, and the exterior AHU supplied the 466 induction draft units (IDUs) with preconditioned air that could be tempered in the summer with chilled water by a chilled water valve installed on each unit. In the winter, the preconditioned air is tempered by a 1,000 watt resistance heating element installed on each unit. The team quickly learned that in the summer, power to the induction risers was secured, which inhibited the perimeter office occupants from controlling the IDUs individually. This caused the chillers to consume more energy to cool the building. By restoring power to the induction risers and enabling the IDUs to be controlled individually, the set points on the discharge air and chilled water could be adjusted accordingly.


The following are some examples of improvements that the building ownership enabled Transwestern to implement to reduce energy consumption:

-- The Energy Management System (EMS) was upgraded to include additional monitoring and control points.
 A computer preventative maintenance system was purchased and installed to schedule, log, and track equipment maintenance and repairs.
     -- The team performs preventative maintenance on each piece of equipment regularly, making certain filters, coils, and strainers are clean.
A base building lighting list was created to ensure the installation of energy-efficient light fixtures for new construction/tenant renovations.
A time clock system was installed to control the lights in elevator lobbies.
Occupancy sensors were installed in offices, halls, restrooms, pantries, and copy/work rooms to turn off lighting during periods of inactivity.
-- Windows were tinted to reflect solar load and reduce building temperature.
Air handling unit controls were typical for a constant volume system but there were major restrictions in the return air pathways. Additionally in some areas, there were not any transfer grills installed as required by the original design. Consequently:

-- Return air pathways were installed as required.

-- The air distribution systems were inspected to locate and remove obstructions in the return air ceiling plenums.

The ability to replace equipment, upgrade controls, and better understand the design and operation of the building has benefitted the team as well as the tenants at 1899 L Street. Over the past 4 years, electric supply rates have risen 51 percent, while the utility expenses at 1899 L Street have only increased by 4 percent. Year to date 2009, the gross KWH consumption continues to gradually decrease while building occupancy has simultaneously increased.


Transwestern has been recognized by the U.S. Environmental Protection Agency (EPA) as an ENERGY STAR Partner of the Year (2004, 2005) and as a Sustained Excellence Partner (2006, 2007, 2008, and 2009) for its outstanding contribution to reducing greenhouse gas emissions through leadership in energy management.



Please note: Narrative information in this profile has been provided by 1899 L Street Tower LLC c/o Transwestern Carey Winston or a representative of this facility. Other building information was verified and submitted to EPA at the time of application. Building energy performance, operating characteristics, and ownership/management may be subject to change over time.

Building Owner:*
1899 L Street Tower LLC c/o Transwestern Carey Winston

Property Manager:*

Year(s) Labeled (Rating):
2009 (88)
2010 (82)
2011 (80)
2012 (78)
2014 (75)
2015 (77)
2016 (76)
2017 (80)

Facility Type: Office

Total Floorspace: 159817 sf

Year Constructed: 1975

Contract Type: None

Technologies Used:
   Stage 1-Recommissioning
   Stage 2-Lighting
   Stage 5-Heating and Cooling Plant