GHT Ltd.: WAMU - 88.5 - American University

System overhaul at a radio station.


The basic schematic of the dedicated outside air system (DOAS) incorporated for the systems replacement at WAMU's new state-of-the-art facility, using central plant, DOAS terminal units (similar to VAV), chilled beams, and energy recovery. Courtesy: GHT Ltd.Engineering firm: GHT Ltd.
2014 MEP Giants rank: 67
Project: WAMU - 88.5 - American University
Address: Washington, D.C., U.S.
Building type: Other
Project type: System overhaul (e.g., mechanical system upgrade, fire protection system overhaul, etc.)
Engineering services: Electrical/power, HVAC/mechanical, energy/sustainability, and plumbing/piping
Project timeline: 1/1/2013 to 6/26/2014
MEP/FP budget: $298,000


WAMU, American University’s nationally renowned public radio station, had outgrown its 23,000-sq-ft home at the school’s Brandywine Building. The station required a new space that could accommodate multiple simultaneous broadcasts, provide office and administrative space for more than 100 staff members, and support future growth. In 2012, American University acquired an existing office building at 4401 Connecticut Avenue in Northwest Washington, D.C., to serve as the radio station’s new headquarters. Originally built in 1987, the 95,000-sq-ft structure required a significant renovation and systems replacement to accommodate a world-class broadcast facility. The energy load required by the studio and broadcast equipment necessitated upgrades to the existing electrical service with provisions to ensure around-the-clock broadcast operations. Design challenges for the new mechanical system included properly ventilating and conditioning spaces with around-the-clock operation needs while being sensitive to the acoustical demands of a studio environment, as well as incorporating flexibility for office and administrative space with a denser staff population and fewer operating hours.


WAMU and American University chose a design-build approach for the renovation and selected a team led by Coakley Williams, with Gensler serving as the project architect. GHT Limited served as the design engineer for all mechanical, electrical, and plumbing (MEP) needs of the systems retrofit and subsequent fit-out. The building’s existing mechanical system was removed and replaced with a dedicated outside air system (DOAS), a highly efficient HVAC system that preconditions required outside air separately from space conditioning air to save energy. The DOAS system delivers the cooled and dehumidified outside air to terminal units in each occupied area, where sensible cooling is performed using chilled water from the building’s central plant. At WAMU, the terminal units consist of fan-powered DOAS terminal units boxes in general office spaces and active chilled beam units in studio spaces, which move a mix of outside air and recirculated plenum air over fan coils and then into the zone that needs to be cooled. DOAS terminal units provide flexibility for the office areas, while chilled beams support a quiet environment for the studio spaces. The core of the system consists of two air-cooled chillers (335 tons combined) , two boilers for heat, and domestic hot water. The chilled water plant provides lower temperature water to a 100% outside air to condition the outside air as well as account for the latent heat in the space, and also provides “cool” water to the DOAS terminal units for sensible cooling. The upgraded electrical service includes new switchgear, panels, and additional capacity to serve the needs of the data center and broadcast facilities. A new distributive redundant uninterruptable power supply (UPS) supports the station’s ability to continue operating in the event of a power outage with the use of a new 750 kW generator located at the roof. Program space includes three broadcast studios and two news studios with dedicated control rooms; multiple editing rooms; and a theater where content is performed in front of live studio audiences. WAMU’s new home also features a mix of open and closed offices for news, programming, sales, marketing, and management staff, as well as several conference rooms and a data center.

Download a presentation about this project here.

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