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Re-envisioned by HKS, the U.S. General Services Administration’s (GSA) $122 million historic renovation of the 350,000-square-foot Federal Building at 50 United Nations Plaza (50 UNP) in San Francisco was dedicated at a ribbon-cutting ceremony on November 6.
GSA’s regional administrator, Ruth Cox, emceed the event, with nototable attendees and speakers including Congresswoman Nancy Pelosi, House Democratic Leader; The Honorable Dan Tangherlini, GSA Administrator; The Honorable Edwin Lee, Mayor of City of San Francisco; Michele MacCracken, Associate Principal and Senior Vice President, HKS Architects; and Cliff Garten, Cliff Garten Studio.
Scheduled for occupancy by more than 500 GSA Region 9 employees, the renovation of 50 UNP, funded by the 2009 American Recovery and Reinvestment Act, is among the GSA’s historical restorations slated to achieve LEED-Platinum certification. The ambitious renovation and repositioning project is the building’s first major upgrade since original construction was completed in 1936.
Designed by Arthur Brown Jr., architect of San Francisco’s City Hall and three other landmark Civic Center buildings, 50 UNP was the final structure completed in a seven-building complex comprising the San Francisco Civic Center, which was placed on the National Register of Historic Places in 1987. The D-shaped building, including an occupiable basement and a 24,000-square-foot interior courtyard, is an excellent example of Second Renaissance Revival architecture, with period-defining features such as distinct horizontal divisions, a rusticated base and classical ornamentation including columns on exterior elevations. The six-story, Beaux-Arts building has been vacant since 2007.
To transform the structure into a high-performance green building, modernizations included a complete seismic upgrade and new foundation; hazardous materials abatement; roof replacement; high-performance, energy efficiency upgrades; A.D.A. compliance and accessibility upgrades; and installation of new mechanical, electrical, heating and plumbing systems. The interiors were reconfigured to create a more efficient, comfortable office space.
“50 UNP has retained its historic exterior and the most significant interior spaces, while bringing the interior workplace into the 21st century,” said Michele MacCracken, AIA, LEED AP BD+C, associate principal and senior vice president with HKS and 50 UNP project manager.
The project leaves intact the center courtyard with an inviting, contemporary design by Cliff Garten, as well as the double-loaded corridors of the four “wings” of the rectangular building that introduce new “nodes” or openings from the corridor into the office spaces in almost all of the wings.
Selected interior spaces, such as the ornate entry lobby and the Nimitz Suite, have been upgraded with minimal visible change, while historic features and finishes have been protected and revived to their original appearance. The building’s historic light fixtures were retained but completely rewired with a modern electrical system, which helped preserve the distinctive period character of the building.
The building’s exterior changes are nearly imperceptible. Much of the building was preserved under historic preservation laws, including the exterior façade, the lobbies, corridors, main stairways and historic office spaces.
Keeping their commitment to the environment, the GSA aligned its sustainability standards with its desire to attain LEED-Platinum certification. 50 UNP is one of seven representative examples of the City Beautiful movement in San Francisco, and a key element in the Civic Center Historic District. As the GSA’s Region 9 Headquarters – housing landlords and builders for the federal branch of government on the Pacific Rim – 50 UNP becomes a showcase for appropriate sustainable measures in a significant historic building.
Indeed, GSA predicts that 50 UNP will realize an annual energy and CO2 emissions savings of approximately 67 percent, in contrast to a comparable building without an EPA ENERGY STAR rating.
50 UN Plaza offers large, operable windows and ceiling fans that, when coupled with the mild California climate, eliminate the need for air conditioning. The windows, spaced 13 feet on-center, also reduce the dependence on electrical lighting and the associated thermal gain. Additionally, the central courtyard ensures that no workspace is more than 20 feet from a natural daylight source.
The main lighting sources are high-efficiency, dimmable fluorescent lights. LED lights are in place for task lighting and the primary source for exterior lighting. Occupancy and daylight sensors control fluorescent lighting to reduce the building’s energy consumption. Solar panels on the north wing roof are harvesting energy for the building’s use and the new green roof, covered in vegetation, will reduce the urban heat-island effect while treating storm water runoff.
“Beyond the simple renovation of a single building in downtown San Francisco, the modernization of the Federal Building at 50 UN Plaza encompasses a wide range of ambitious goals at the center of a sustainable agenda: how to save what we have, reduce what we use, and at the same time, allow people to be healthier and happier in their work environment,” said Kirk Teske, HKS principal and chief sustainability officer. “We think our team hit all the marks.”
The original steam radiators – which are in remarkably pristine condition – were reused and equipped with individual controls for heating. Domestic water usage is reduced by 40 percent by replacing the original plumbing fixtures with water-saving modern equipment. For the landscaping, highly efficient drip emitters have replaced spray irrigation. A grove of birch trees planted in the central courtyard connects building occupants to the natural environment, a practice that has been shown to increase both efficiency and tenant satisfaction.
According to MacCracken, one of the more significant challenges HKS faced on the project was what to do with the original windows, which required refurbishment rather than replacement. The original double- and triple-hung wood-framed, divided lite windows were completely restored to their original state with low-VOC paint, sash replacements, new hardware and counterweights to make the windows fully operable and new energy efficient glass to reduce solar heat gain.
The building’s location at the center of one of the world’s more environmentally forward cities helps support GSA’s sustainable agenda. The site is adjacent to several modes of public transportation, including Bay Area Rapid Transit (BART), the municipal railway and several regional bus lines. Bicycle racks and changing locker/shower rooms are provided for employees who choose an emissions-free commute and ride their bikes to work.
The project was completed in two phases. HKS was awarded the design contract in August 2009 with the design effort commencing immediately. The majority of early Phase I work included the demolition/environmental remediation portion, completed in May 2010 by Hathaway Dinwiddie, the general contractor. The Phase II renovation work was completed this July, on time and under budget.
HKS, Inc. is a leading architectural design firm ranked among the top six architectural engineering firms, according to Building Design+Construction magazine. Since its founding in 1939, HKS has completed construction projects totaling more than $75 billion in more than 1,263 cities located in 80 countries. The firm operates from 27 offices worldwide.
For more information, contact Julie Wellik at firstname.lastname@example.org.