Construction began last month on the new home of the U.S. Embassy in London. The cube-shaped building is located atop a colonnade base, within which the glass-enclosed lobby and entrances are located. © KieranTimberlake/Studio amd
Slated for completion in 2017, the first home of the U.S. Embassy in London to be located outside of Grosvenor Square is now under construction.
November 26, 2013—Historic cities do not typically lend themselves to sweeping new developments that are centrally located and include broad stretches of parkland, shopping, residences, and office developments along a riverfront. But London is getting just that in the 195 ha Nine Elms development, located along the city’s South Bank. Heavily damaged from bombing during World War II, the area had developed into a light industrial area in the postwar years. It is now undergoing redevelopment, which includes the construction of a new United States embassy that is ushering in a new generation of design for diplomatic missions.
November 13 marked the official ground breaking of the new U.S embassy. The design of the structure, conceived by the Philadelphia-based architecture firm KieranTimberlake, combines the dueling needs of high security and a welcoming appearance. The structure also strives to meet strict environmental standards. The cube-shaped building is located atop a colonnade base—within which the glass-enclosed lobby and entrances are located—and is visually dominated by its prismatic envelope, which generates its own solar power. It is situated in parkland that doubles as a security-conscious perimeter space without the need for fortress-like fencing.
“The inspiration [for the design] comes from a holistic understanding of all the elements—site, program, context, environment, security, [and] wellness—that makes up a project of international significance,” said James Timberlake, FAIA, a design partner of KieranTimberlake, who wrote in response to questions posed by Civil Engineering online.
“We knew that the Department of State and the U.S. government in their special relationship with the U.K. desired an environment for diplomats, and it was paired with being a ‘diplomat for the environment’ [in] a high-level performance, iconic building of great beauty and serenity,” he said.
Spiraling landscape architecture wraps around and into the
structure, creating indoor and outdoor gardens. The site merges
with the surrounding development that is currently under way
along London’s South Bank. © KieranTimberlake/Studio amd
In this age of increasing international terrorism, embassies have shifted from being locations of diplomatic welcome to security-conscious strongholds, according to the design and access statement on the structure that was filed with the Wandsworth Council, the local governing body of the borough in which the embassy will be built. “Recognizing that this message is both an impediment to successful diplomacy and an inaccurate representation of our values and aspirations, the Department of State has undertaken an ambitious project to rethink the architecture of embassies,” the design team wrote in the design and access statement.
As such, the new embassy in London is meant to be a “first step toward a new generation of embassies,” according to the statement, and one that is based on the premise that security and transparency need not be mutually exclusive.
The building is founded on a pile-supported raft foundation and includes a ground-source heat pump formed from closed-loop wells drilled 140 m deep. It also includes a central building core that offers typical elevator and stair circulation elements and restrooms. The first two floors are public levels designed for embassy business, and on the upper floors the internal core is surrounded by column-free, open office space that can host flexible workstations.
Vehicles can access the building on either side, via secured entrances that also provide access to an underground parking structure and underground loading dock, according to the design and access statement.
The building is wrapped in a double-layered building envelope. The outer envelope comprises individual layers of ethylene-tetrafluroethylene (ETFE) stretched over a network of thin aluminum members that work in tension and compression. The outer envelope wraps the building to the east, west, and south, acting as a screen that shades the building interior from undue solar gain. The envelope also collects solar energy via thin-film photovoltaic panels located on the lower portion of the ETFE foils. The prismatic pattern of the outer envelope has been shaped to allow daylight to reach deep into the floor plates without excessive heat buildup.
“At 95 percent transparency, [ETFE] is applicable as a substitute for glass materials, especially when material weight is a factor in sizing structural members,” the design team noted in the design and access statement. “ETFE is likewise chemically resistant to attack, performing very well in the presence of fresh water, salt water, weak acids, strong acids, weak alkalis, strong alkalis, and organic solvents.”
A central building core provides flexible, column-free office space
within the upper floors of the building. Six two-story garden
spaces will double as circulation points between the floors.
© KieranTimberlake/Studio amd
A high-performance, multilayered, glazed curtain wall with an aluminum frame forms the inner layer of the building’s envelope. It has been designed to meet stringent security criteria while optimizing daylight admission, views, thermal performance, and efficiency, according to statement. Rooftop mechanical equipment will be hidden beneath a full photovoltaic array.
While embassies are typically located on compounds with publicly accessible spaces, ceremonial and symbolic spaces, secured areas, and office spaces—often housed in separate buildings—this was not possible in London. The design team carefully choreographed the entrance and circulation points to keep these elements separate while at the same time contained within the same building. Separate entrance and egress points have been created for service deliveries, the public, and office workers and diplomatic visitors to the secure areas of the building. The embassy is designed for approximately 800 staff members, with a peak visitor total of approximately 1,100 visitors a day.
The concept of a spiral has informed the design of the building and its environs from the very beginning. “The ‘spiraling’ form of the landscape is expressed through grading, walks, and planting in a way that simultaneously opens out to the city beyond and spirals inward as it envelops and then moves up into and through the embassy building,” the designers wrote in the statement. Pedestrian and bicycle access to the site is guided by the pathways that surround the building, and are integrated into those of the larger Nine Elms development.
Inside the building, the spiral becomes tighter as it rises through the structure, encompassing six internal two-story garden spaces that also offer internal circulation points. Three of the gardens are conceptualized as fully interior “winter gardens,” according to statement, while three are placed so can function as exterior terraces. “These gardens are a combination of real and [created] elements which depict American landscapes … representative of the home country,” Timberlake said. They will also act as gathering spaces for employees and visitors, he said.
The gardens represent six zones from around the United States: “Pacific Forest,” “Midwest,” “Canyonlands,” “Gulf Coast,” “Mid-Atlantic,” and “Potomac.”
Security measures have been seamlessly incorporated into the landscape architecture to allow for visual continuity and connection between the site and the Nine Elms development, according to Timberlake. The landscape architecture also integrates well-known U.S. design elements and plantings that have become part of the U.K. landscape over the last 300 years.
The 2,300 sq m pond that frames the north side of the building offers multiple functions. It collects rainwater and acts as a storm-water catchment, according to the design and access statement. It also serves as a collection point for excess nonpotable water from the building’s on-site water treatment system, according to the architects. The pond water will also be used for drip irrigation of the landscape and to support the internal gardens.
“The exterior landscape, which incorporates many critical sustainability features—the pond, the meadow, et cetera—all use landscape language and species that are U.S. landscape elements that the British brought back to the U.K. during the colonial periods, and now have established themselves as integral in the U.K. species array,” Timberlake said. “So this new building is integrated fully into a landscape and rooted well into the fabric of the city.”
The building is located on 2.16 ha between the Battersea Power Station, listed as a Grade II* structure with English Heritage, and the Vauxhall Transport Interchange. (See Battersea Power Station to Become Commercial, Social Center,” Civil Engineering magazine, May 2005, pages 23-24.) Once the new building is completed, the U.S. Embassy will move from its Eero Saarinen-designed building in Grosvenor Square, which has been its home since the building was completed in 1960. This will be the first time since diplomatic relations opened in 1785 between the newly formed United States and Great Britain that the U.S. embassy will be located outside of Grosvenor Square, according to the architects.
The New York City-based engineering firm Weidlinger Associates, Inc., is completing the structural and blast engineering for the project; the global engineering firm Arup is completing the mechanical, electrical, and plumbing engineering, as well as the sustainability and civil engineering design. Philadelphia-based OLIN collaborated with KieranTimberlake on the landscape architecture.