Eco-Cube for American Embassy in London

— Having outgrown its 1960 embassy, a Kennedy-era modernist design by Eero Saarinen, the U.S. State Department has decided that London is too important to build one of its conventional insults to local sensibilities.

Sometime in 2013, a glass cube rising 12 tall levels atop a shrubbery-fringed mound and estimated to cost $500 million will sprout on the south bank of the Thames.

U.S. Ambassador to the United Kingdom Louis B. Susman announced the selection of a design by the Philadelphia architect KieranTimberlake yesterday in London. The firm, known for adventurous, energy-conserving designs at Yale University and in Washington, beat big-name Pritzker Prize winners Richard Meier, Thom Mayne (of Morphosis) and Pei Cobb Freed.

From renderings released by the State Department, the design looks to me like the architectural face of Obama-era diplomacy. The embassy is discreetly fortified and ambitiously, conspicuously green.

Diplomacy has been badly served by the last generation of embassies, in which security has trumped both utility and dignity. Repellant fortresses with pinprick windows set behind high walls in distant suburbs have become the rule.

Truck bombers dictate embassy design. To dissipate the force of explosions, the State Department insists on 30-meter building setbacks (about 100 feet). No site large enough was affordable within central London, so State banished the embassy to an unglamorous site on the south bank of the Thames near Vauxhall.

Hello MI6

Amid a jumble of motley warehouses and isolated by a main rail line, the embassy will rise from a five-acre plot on Nine Elms Lane as the centerpiece of an 18-acre residential and commercial redevelopment by Ballymore Properties.

At least MI6, the British secret intelligence service, is close by.

Green is an easy architectural image-maker in a messy world, and firm principal James Timberlake pledges to deliver a building that is carbon neutral—an audacious goal.

The all-glass office block is a welcome contrast to the defensive crouch of most American embassies, though it looks as if it is covered in high-tech tufted upholstery.

The pliable plastic material, called ETFE, will stretch tent-like over rods projecting from the outside walls. It will form insulating pillows that taper into vertical and horizontal fins. Tuned to optimal sun angles, the fins will harvest daylight when useful and shade when needed.

Photovoltaic film will be laminated onto the ETFE to collect solar energy when sun makes a rare appearance.

This strange building surface, both bristling and soft, is the most conspicuous element of an extraordinarily strict environmental regime. Even the tendency of birds to smash themselves into glass buildings has been taken into account.

Carbon Neutral

With an additional array of PV panels on the roof and a heating and cooling system that uses organic matter for fuel, the building will be energy independent. It achieves carbon neutral status by supplying heat to the rest of the development at times and feeding surplus power into the grid.

The glass cube sits aloof on beefy columns atop a shrub- covered mound, which will be partly open to the public as a garden. The mound's mass can dissipate the explosive force of a car bomb, while avoiding the menacing walls and fences that deface so many consular facilities. A pond on the north side offers a pleasing amenity, while acting as another obstacle to would-be bombers and a heat sink for the biomass plant.

Visitors, guests, and visa seekers, some 1,100 a month, will enter through a security checkpoint in a grass-topped pavilion set into the mound to separate gun-toting wackos from the main building.

Bunker Mound

With so much attention devoted to the green features and security, the design does not coalesce into a persuasive statement about America. The beefy columns uneasily prop the cube's expression of technological prowess over the mound. The prettifying plantings, can't fully disguise the mound's purpose as a bunker.

Even in less troubled times, embassy designs have tried on a variety of unconvincing architectural ideas of America, like anglicized Italian palaces or columned plantation houses. At Grosvenor Square, Saarinen unsuccessfully melded modernist openness, American informality, and old-fashioned dignity.

Of course, it's difficult to create a compelling statement when America's place in the world is hotly contested at home and its international intentions are debated everywhere. America can't even create a coherent climate-change policy.

This ambivalent embassy perfectly sums up the extraordinarily difficult Obama moment.