Similar in scale to the Kahn building, the 300-foot-long, 22-foot-high building is composed of two parallel wings stretching from north to south, connected by two glass passageways. To the rear, the west wing will have a green sod roof, which appears to rise out of the ground with berms on either end and concrete retaining walls on the sides. The front, east wing is topped by a glass, steel and wood roof system. The wafer-thin top layer of this system, which features louvered photovoltaic cells, hovers above the east wing's most prominent feature: enormous laminated wood beams that appear to float above the concrete and glass walls and which are held aloft by square concrete columns.

The plan and elevation of the east wing, which faces the Kahn building, is tripartite, which mirrors the tripartite plan and elevation of the Kahn building. This is the most overt of the Piano building’s numerous echoes of its esteemed predecessor. The facade’s central, 100-foot-long recessed glass entrance bay is flanked by two crisp, light gray concrete bays of equal length. A subtle verticality offsets the emphatic horizontality of the facade with mullions repeated at five-foot intervals and with four columns. The columns reappear on the north and south sides of the east wing, but more closely spaced as a colonnade.

Twenty-nine pairs of wooden roof beams, weighing a total of 435 tons, span the interior and extend to the exterior as an overhanging canopy. As well as providing support for the roof system, the 100-foot-long beams of laminated Douglas fir add visual weight and warmth within largely continuous, changeable and airy interiors.

“In its marshaling of light, materials, scale and plan, Piano’s lean post-and-beam structure will provide an enduring counterpoint to Kahn’s solid, vaulted forms,” says Eric M. Lee, director of the Kimbell.

Most visitors will reach the entrance of the Piano pavilion from a new underground parking garage. It is likely that their first sight will be Kahn’s masterful entrance portico. By situating his structure facing Kahn’s, Piano has reinstated the primacy of the west entrance of Kahn’s museum, correcting the tendency of visitors up to now to enter at the lower-level east door, which Kahn considered the secondary entrance. The positioning also rewards visitors within the Kahn building with a thrilling view across the landscape and through layers of glass to a dramatic light well at the rear of Piano’s new building.

As always in his museum designs, Piano continues to experiment with ways to animate and direct natural light, here with a roof system that is notable for its integration of the large wooden beams into a system of north-opening aluminum louvers, fritted glass, solar cells and stretched, silk-like scrims. He also channels light and provides unexpected sightlines by dramatically slanting some of the building’s walls. The most dramatic example is the deep and broad concrete light well that provides a spectacular backdrop to the stage in the 298-seat auditorium, with bright red, raked seating. Canted walls also channel light in two sets of stairwells connecting the upper and lower levels: one leading from the main entrance to the underground garage, and the other descending from the upper level to the lower auditorium entrance.

While retreating from view when seen from outside, the west wing of the pavilion is deceptively spacious. It not only accommodates the auditorium but also houses a smaller exhibition space for light-sensitive works, a library and spaces for education.

In the east wing are galleries of elegant, refined concrete and glass, flooring of white oak and a roof-and-ceiling system that harvests natural light, preserving a palpable sense of the day outside while providing optimal light levels for the art. Natural light, carefully filtered, will be supplemented by artificial light when appropriate.

It is expected that the Kimbell’s renowned permanent collection of European art will regularly be on view in the Kahn building, with other masterworks from the collection—including superb examples of Precolumbian, African and Asian art—on display in the Piano pavilion. The principal function of the new building’s southeast gallery space will be to display temporary exhibitions. Notes Lee: “With this expansion, for the first time, the Kimbell will be able to showcase the breadth of its small but extraordinary permanent collection while simultaneously accommodating changing exhibitions.”

As well as the $135 million expansion project, which includes the creation of an underground parking garage, the Kimbell has also undertaken the renovation of the Kahn building and a landscaping program for its campus designed to preserve as much space as possible for open lawn, ornamented with shrubs and trees.

A New Green Building
Highly energy efficient, with a green roof accessible to the public, the Piano pavilion will use only half of the amount of energy required for the operation of the Kahn building.

“Because only a third of the interior is above ground, the museum will see greatly reduced demands for heating and cooling,” says Renzo Piano. “In this way, it is the overall design, as well as the solar technology built into the roof system, that yields important energy savings. This is the way it should be: designing for energy savings is not an ‘add on,’ but, rather, the proper way to build.”

The New Kimbell Campus
The Piano and Kahn museum buildings occupy a three-and-a-half-acre campus of public green space. The new landscaping is designed to extend Kahn’s vision and maximize green space to the greatest possible extent. The Piano pavilion was designed with this goal in mind: its 19,200-square-foot green roof, which is tucked behind the front wing, connects to the lawn on its south side, offering the public an elevated view of the Kahn building—and other sites in the Cultural District—from a lawn for repose and recreation.

Some 320 new trees are being planted around the site, including 47 thirty-foot-high Allée elms that will visually connect the Piano and Kahn buildings. The elms will reestablish the much-loved pattern of the trees that were removed for the construction of the new building—trees that once lined a street that had been transformed into a lawn before the Kahn building opened in 1972. In addition, 52 mature yaupon holly trees, each measuring 12–15 feet tall, are being planted in the grove outside the Kahn building’s west entrance. As it has for decades, the shade of the yaupons will provide a transition from the light of day to the magical light of Kahn’s interior.

The Construction Team
The cool and silken sheen of the architectural concrete, an important element of the design of the Piano pavilion, was achieved under the supervision of the Dottor Group of Venice, Italy, and Reg Hough of Rhinebeck, New York. The concrete was poured in place by Capform of Gallatin, Texas. The wooden beam system was designed in collaboration with the New York–based Guy Nordenson and Associates as structural engineers, and the east curtain wall in collaboration with FRONT as facade consultants.

The executive architect is Kendall/Heaton Associates, Inc., of Houston; the construction manager is the Beck Group of Dallas/Fort Worth. The mechanical engineers are Arup Consulting Engineers, London and Summit Consultants, Fort Worth.

The project is being managed by Paratus Group, project managers, of New York City.

The Renzo Piano Building Workshop is the designer of Europe’s tallest building, The Shard—which opened in London in summer 2012 in time for the Olympics—and of some of the world’s most beloved museums, large and small, including three in Texas: The Menil Collection and Cy Twombly Gallery in Houston and the Nasher Sculpture Center in Dallas.

More information may be found at www.kimbellart.org.