Education Executive Agency and Tax Offices
Northern Exposure: In the sea-swept Dutch state of Groningen, UNStudio and its partners create a building that rides the breeze.
A white form sailing over old woods and a highway bypass, the city of Groningen’s newly opened Education Executive Agency and Tax Office—known locally as the cruise ship or the lantern—is built to catch the wind. This is apt for a place that’s forever looked to trade and commerce over the blustery edges of the northern Dutch flatland toward the North Sea.
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Built for $185 million (€130 million) in four years by a broad private design and engineering consortium called Duo2, the government building stands over 300 feet with 24 working floors. The Duo2 collaborators feature a big team from Amsterdam—architects UNStudio; multinational engineers Arup; landscape architects Lodewijk Baljon; and general contractors Strukton. Duo2’s ambition is to create one of the most energy-efficient buildings in Europe.
The dense oak park across the street is a de facto partner in the project, bringing a hush onto the small city lane leading to the building entrance. If it feels a little ad hoc, that’s because it is, explains a UNStudio senior architect. The real main entrance is not yet built—it is part of a flowing pavilion, garden, and underground parking garage plan due for construction over the next few years. The garden will stream daylight to the levels below, and the garage will have space for 675 cars and 1,500 bicycles. This is a project still in motion.
Two distinct operations are housed here: the Dutch federal tax service and the university student grant system. Security is tight in the entrance and lower sections of the building, with the lobby and public-facing help stations sealed from the escalators leading from the ground floor to the first; a broad staircase leads from there to the next level where the big call centers for tax and loan servicing are housed.
Above this, the two building cores support an upper tower shaped like a ship’s smokestack for the student services, with a longer supporting prow underneath housing the tax office floors.
Complex operations are going on underneath the smooth exterior of the building’s skin. To look at the inclined columns and the skeletal structure of the building is to look at a cross between an airplane wing and the giant curving ribs of a whale. Visitors and harried tax customers stream in and out of the new lobby unaware of all this, footsteps padding softly on recycled-rubber flooring.
Rising through the stories of the building, one can plainly see the forlorn beige towers a few blocks away that until earlier this year used to house these same government functions. The half-stripped towers serve as a vivid and windowless contrast between present and past. A disheveled potted plant spotted through a cracked door in one of the old structures hints at the drab institutional spirit from which the new building tries to break. “We wanted new concepts that would be environmentally sound and allow us to be more efficient by using a new system of flexible workspaces,” says Hans Maat, project manager for the tax office. “But [the building] also has the benefit of boosting morale.”
While there are some who would complain about a tax office spending money for showcase shelter, the energy efficiency of the building should save costs. A Dutch energy-efficiency rating has been applied to the building with respect to its methods and use of heating, cooling, lighting, warm tap water, ventilation, and pumps. The rating coefficient is based on the overall energy use of new buildings versus similar buildings of the past. The Duo2 building gets a 0.74 rating against the standard 1.1 for office construction.
“This building shows how contemporary computational design can combine the complexities of the architectural ingredients needed in an office building, and then precisely control the major details of the project,” says Ben van Berkel, cofounder and director of UNStudio. Van Berkel says computer-assisted design gets really interesting only when one can apply environmental principles to the building innovations possible with it.
UNStudio and engineering collaborators Arup forged one of the building’s signature elements, the looping white aluminum “fins” banding each floor of the building to meet both ecological concerns and energy efficiency alike.
One way it does this is by guiding the wind over the top of the tree canopy below. The building site clashes with the local prevailing southwest wind, meaning the Duo2 building is often hit broadside with a stiff breeze. “Managing the wind in this project is very important because the building cannot disturb the nearby woods,” Arup mechanical engineer Jeroen Verwer says in a video clip about the project. If the winds swept directly down off the building, they would dry out the soil and damage the old-growth trees, as well as disturb bat habitats and the forest ecology.
So they created a more aerodynamic shape for the building and decreased the floor-to-floor height, Verwer adds. This height reduction, which shaved 21 feet from the original plan, also meant the saved construction resources could go into other design elements, like natural heating and cooling wells, more expensive recycled materials, and the fins on the facade.
Calculating the fin placement around the building was a job for Arup, as they vary in shape based on their location. The fins are more than a wind control. They also contribute to shading, daylighting, and ventilation efficiency. They are positioned to keep sunlight from coming directly into the office space during the summer, and to help in heating the space during winter when the sun is lower in the sky.
The reflected light means workers can use less intense overhead lighting. The lighting power density of the DUO2 building is 0.75 watts/ft2 instead of the 0.94 watts/ft2 in a typical Dutch office building, Arup’s Verwer says. Efficiency is aided by daylight and occupancy sensors. All this results in predicted lighting energy use of 0.68 kWh/ft2 (2.32 kBtu/ft2) instead of 1.69 kWh/ft2 (5.77 kBtu/ft2) for a typical office—saving 60 percent.
Wind is also a source for much of the building’s ventilation. On the lower levels fresh ambient air is pumped through the basement; for the upper tower, the vital 11th floor—which houses the data center, a major source of heat—is slatted with adjustable vents over a grill to catch the wind flowing down off the upper-floor fins and directly toward the building.
Fresh air is directed through vents in each floor, escaping through stylized punch-holes in the top of the room and directed out into the core, which draws the circulated air through the roof in a chimney effect. This vertical-motion ventilation technique, where the air moves from bottom to top in order to discourage microbial growth, is used in the sterilized rooms of hospitals. To stand in the 11th-floor breezeway in front of the grill is an illustrative way to test the system’s efficacy. It’s not quite Ghostbusters, but close enough.
Rounding out the building’s green bona fides are concrete core heating and cooling supported by four 300-foot-deep wells, two for cold and two for warm, which circulate water back and forth during summer and winter through the building to aid in climate control.
Human systems are part of the mix, too: there are few personal workstations. Utilizing a form of hoteling, colleagues clean desktops and store their items in lockers at the end of each day, finding open space when they need it. In this way a building with 2,500 workstations supports 3,500 employees.
Colors in each wing lend identity to the space, and workstations are numbered off a grid. The main corridors are different sizes—easy to tell apart. “And there is a panorama of the city always when you are looking out,” van Berkel says. “You can see two sides of the city. It orients you.”