Feats of Fabrication: Palazzo Italia's "La Vela"

Glass wave-like roof stretches imaginations, presents exciting challenges for fabrication and installation
Katy Devlin
September 9, 2015

A 43,000-square-foot wave of glass and steel drapes over the new Palazzo Italia in Milan, Italy. Dubbed “La Vela” (The Sail), the glass roof is the architectural centerpiece of the six-story pavilion, built for Milan Expo 2015, the international exhibition that takes place May 1 to Oct. 31 on 490 acres of fairgrounds just outside of Milan. The exhibition is host to more than 140 participating countries and is expected to draw more than 20 million visitors.

The design for the Italy Pavilion was chosen through an international competition in 2013, with Italian firm Nemesi & Partners Srl creating the winning project—a 155,000-square-foot building clad in an intricate branch-like façade of decorative cement panels and topped with an undulating glass roof.

“Palazzo Italia [was] conceived as a landscape-like architecture where the building, through its structure and volume, takes on the appearance of a tree/forest into which visitors can plunge for a thrilling experience,” said Diana Bracco, president of Expo 2015 and commissioner for the Italian Pavilion, in a release.

“Our architectural design for the Italian Pavilion takes inspiration from an urban forest,” added architect Michele Molè of Nemesi & Partners. “The intertwining lines generate an alternation of light and shadows, of full and empty spaces, from which a natural architecture comes to life.”

The glass roof completes the architects’ vision, as an interpretation of a forest canopy, allowing natural light from above to flood the interior space, according to Nemesi & Partners officials.

“The dome reaches up to a height of [174 feet] over the interior square of the Pavilion of Italy, where the large glass skylight lets the natural light go through over the central [atrium] and the main corridors,” describes Roberto Arias Fernandez, head of communications for the glass fabricator, Tvitec. “This gigantic structure represents the symbolic center of the whole architectural project.”

The roof structure features large architectural glass and photovoltaic panels in a wide range of shapes. The complexity of the design, with the varied panel sizes and shapes, presented notable challenges to Tvitec, according to company officials.

“’La Vela’ was one of those projects that, based on the difficulty, becomes a new challenge, and once the project is finished, the dream has become a new reality,” according to Tvitec’s leadership team, Javier Prado, Alberto Sutil and David López. “It was a project based on irregular shapes with huge dimensions. Each small detail was of maximum importance in order to match the final target.”

The insulating and laminated glass panels were fabricated at Tvitec’s facility in Cubillos, Spain. “One of the most important technical difficulties of the glass supply for this spectacular project was the processing of dozens of large panes with different geometry: triangular, rectangular and trapezoidal,” says Tvitec’s Arias. “The fabrication of every single unique shaped glass was extremely complicated.”

To ensure the glass was cut precisely, Tvitec relied on computer technology. “For such design it’s extremely important to work with the right software to avoid having large tolerances in glass cut. Otherwise, all the different shapes would not have matched perfectly,” Arias says.

The roof canopy weighs 386 tons and features a complex structural steel system of tubular steel armor primary supports, cross-section profiles and vertical struts in the form of plates. Stahlbau Pichler engineered and supplied the steel structure, and completed the canopy installation.

The project team relied on computer modeling throughout the process. 3D and BIM models were used during design, with every component of the structure included, ensuring the project could be actualized. In addition to computer modeling, the team also completed a full-size mock-up of a segment of the glass canopy.

The attention to precision in the fabrication and design processes extended into the installation as well. “A good logistic plan as well as good glass labeling was really crucial,” Arias describes. This ensured that installers from Stahlbau Pichler received the right glass panels at the right time during the installation process.

The project is a feat of complexity, and also of efficiency. Nemesi & Partners designed Palazzo Italia to be near zero net energy. The use of photovoltaic panels and the high-performance glass in the canopy helps the project achieve its energy performance goals. The insulating, laminated units feature low-iron glass with a SunGuard Light Blue 52 HD coating from Guardian Industries. The glass “contributes to the promoter’s main target: to get a high energy-efficient building beyond its outstanding aesthetics,” Arias says. The photovoltaic glass panels were supplied by EnergyGlass.

“On top of the energy saving and efficiency criteria, strict guidelines and requirements have been taken into account in order to secure the integrity of ‘La Vela,’” Arias continues.

In addition to the rooftop glass, the project also features glass curtain wall panels beneath the “tree-branch” façade. The curtain wall was engineered and supplied by ABeC Façade Engineering.

Nemesi’s design partners included Proger Engineering & Management, engineering and cost management, structures and systems; and engineer Livio de Santoli, sustainable energy. The general contractor was Italiana Construzioni Spa. The tree-branch façade was supplied by Italcementi SpA and Styl-Comp Group.

The Palazzo Italia building is the only permanent structure at Expo 2015. After the conclusion of the expo, the pavilion will be used as an art space for traveling exhibitions.

Katy Devlin is editor for Glass Magazine. E-mail Katy at kdevlin@glass.org.