When the Goede Doelen Loterijen (GDL), the Netherlands’ largest group of charity lotteries, decided to consolidate its offices, its 600-plus employees had one request: to retain the park-like environment of their former offices, which were set in a series of historic villas near Amsterdam’s 120-acre Vondelpark. That wish inspired Benthem Crouwel Architects’ design for the dynamic roof topping the GDL’s new location in a building that had sat vacant for nearly a decade near the city’s Zuidas business district.
Like a tree canopy twinkling with metallic leaves, the underside of the skylight-studded roof features 6,840 polished-aluminum and folded ceiling tiles designed to send dapples of daylight across the surfaces below. Supported by six branching, tree-like steel columns, the 43,270-square-foot roof covers the 85,000-square-foot building and entrance plaza, unifies the GDL’s staff members, and broadcasts the organization’s social and environmental mission to the Zuidas neighborhood. To date, the lottery has reportedly contributed more than €7 billion (nearly $8 billion) to charities in developing countries. The extension of the roof over the entrance plaza invites the public to engage with the building, as does the addition of the restaurant La Lotteria.
“We wanted the roof, which is visible everywhere, to be recognizable and a symbol of the GDL,” says Saartje van der Made, a partner at Benthem Crouwel, which has offices in Amsterdam and Düsseldorf, Germany. The roof does more than offer shelter from the elements, she notes. “By adding a layer under the roof, the so-called ‘foliage,’ we prevent too much warming in the summer and [create] an ever-changing play of light, just like in real nature.”
The grand gesture also solved multiple architectural challenges, including the requirement that the building be net-zero energy. “By designing a roof that covers the entire plot … we were also able to collect as much rainwater as possible and install nearly 1,000 solar panels, making the roof one of the most sustainable features in the plan,” van der Made says. The photovoltaic system generates 300 megawatt-hours annually—enough to power nearly 100 households.
To design the ceiling and roof, the architects began with sketches and then used a laser cutter to explore the look and feel of the canopy’s tiles, or leaves, through scale models. Those models became vital as the team began contacting manufacturers to assess the design’s feasibility, says Benthem Crouwel building engineer Cees Zuidervaart. Representatives from the Rotterdam, Netherlands, office of Hunter Douglas “came up with a solution based on an existing ceiling system, in consultation with their development department,” Zuidervaart says.
The reflective tiles are manufactured from 95 percent recycled aluminum and 5 percent corrosion-resistant, high-quality aluminum alloy, according to Hunter Douglas. Each tile measures 2 feet square and is cut and bent to curve downward at different angles, making four triangular leaves. To create a repetitive yet variegated pattern, the architects designed seven tile types with varying degrees of “openness,” which were combined to generate a total of 58 different ceiling panels, or sets of four tiles, according to Hunter Douglas. Each panel was numbered to ease installation.
To account for wind loads, exterior ceiling tiles are 2 millimeters thick, whereas tiles inside the building are 1.5 millimeters thick. The exterior tiles also fit more snugly into the frame, a lightweight aluminum armature sprayed with a white finish so as to disappear into the sky overhead.
The armature supporting the foliage suspends from wide-flange steel roof beams that, in turn, tie into the building’s existing concrete structure and the tree-shaped columns. The branching columns, the largest of which is 50 feet tall and has a reach of nearly 60 feet, were manufactured by Bentstaal in IJsselstein, 30 minutes south of Amsterdam. The most prominent columns, in the building’s multistory atrium and its exterior plaza, are finished with a matte-gray, fire-resistant coating.
After two years of construction by Dutch contractor J.P. van Eesteren, the building opened in 2018 and earned an Outstanding rating in the BREEAM performance rating system, making it the most sustainable renovation in the Netherlands to date. (Its final score was 92.6 percent, 7 points above the bar for Outstanding.)
The recognition is in keeping with the GDL’s mission. “The organization consciously opted for renovation and expansion of an existing building,” van der Made says. In creating an iconic ceiling-and-roof system that mimics both nature and the GDL’s former site, Benthem Crouwel hopes to have made a building that is as beloved as it is beautiful.