A Danish Team Passed an Uphill Test to Deliver a Power Plant with a Ski Slope on Top
BY AMY WILKINSON
PHOTOS COURTESY OF AMAGER RESOURCE CENTER
“Hedonistic sustainability.” That's how Bjarke Ingels, founder of architecture firm Bjarke Ingels Group (BIG), describes the newest Danish waste management facility, CopenHill. Completed in October 2019 in Copenhagen, Denmark, the facility is far from typical.
At the base of the structure, also known as Amager Bakke, is a state-of-the-art waste-to-energy plant, capable of converting 440,000 tons of waste into energy each year (equivalent to electricity and heating for 150,000 households). At the summit is a lush recreational park, featuring a 450-meter (1,476-foot) dry ski run and hiking trail as well as an 85-meter-high (279-foot-high) artificial climbing wall, reportedly the tallest in the world.
The design isn't just about fun and games for local residents—it's also built to push the Danish capital into the new frontier of sustainability. Project sponsor Amager Resource Center hopes the new US$670 million facility will serve as an integral step toward Copenhagen becoming the world's first carbon-neutral capital city—a goal it hopes to achieve by 2025.
Amager Bakke replaced the 50-year-old Amager incineration plant, and plans for that switch stretch back more than a decade, with engineering firm MOE winning the engineering consultancy bid in October 2009. BIG came into the picture in 2011, winning an international design competition with its wedge-shaped structure and sloped green roof.
“The major feasibility question for the project team, as I remember, was the idea of having people on the roof,” says Peter Madsen Nordestgaard, technical director of steel structures, MOE, Copenhagen. “We had to answer: Is it safe? Can the municipalities accept it?”
—Peter Madsen Nordestgaard, MOE, Copenhagen, Denmark
But the design demanded a novel approach to the interior as well. To achieve the desired slope, the team arranged all machinery and rooms inside by height. Visitors can ascend to the roof by platter lift or carpet lift. Or they can use an internal elevator with full glass panels that offer a glimpse at the inside operations: furnaces and turbines converting waste to energy around the clock, as well as 10 stories of administrative offices, including an education center for workshops and sustainability conferences.
The team also designed the facade with the interior in mind. Massive aluminum blocks—each measuring 1.2 meters (3.9 feet) high by 3.3 meters (10.8 feet) wide—alternate with glazed windows, creating a weave pattern that allows daylight to stream deep into the facility, reducing the need for overhead lighting.
With so much complexity, project plans allotted Mr. Nordestgaard an entire year to sketch and render the building's superstructure in 3D before sending out the plans for steel contractor tender. In order to keep things moving, the team divided work on the building into sections so that each compartment could be independently constructed and puzzled together later.
“Our contractor from Germany could deliver some of the first part of the building in the one end while we were still making detailed designs of the connection at the other end for optimizing planning,” Mr. Nordestgaard says. Involving the contractor early in project plans also meant less back-and-forth during execution, he says. “All contractors have different ways of doing things, so it's good to involve them before you've finished with your detailed designs, so you can adapt.”
From the beginning, the superstructure design team had to account for the dense foliage along the massive ski slope of its roof—meaning the weight of every last rock, bush and tree had to be tallied.
The MOE team worked with landscape design firm SLA for the green space plan and developed practical solutions for problems the steep incline posed. For one, how would realistic topographical elements be rooted in place without having them slide right off the hill? The landscapers ended up sourcing a special material for the hiking trails that they could cast by hand, on-site, allowing them to secure items directly to the slope. Another challenge: Would the design use real or fake trees? Fake trees would weigh less, because they wouldn't need heavy soil to take root. Ultimately, the team stuck with real trees, which helped achieve the project's larger strategic goals of promoting sustainability. The team prioritized local plants to mimic the Nordic wilderness, planting 300 pines and willows along with 7,000 bushes.
As a first-of-its-kind structure, there were few lessons learned to apply for teams tasked with reinforcing the parts of the superstructure that would carry the foliage and its surrounding soil. While the team drew inspiration from other man-made slopes around Europe, there was no escaping the project's groundbreaking nature.
“You can collect something similar but not exactly like this,” says Sten Willer Christensen, project director, MOE, Copenhagen.
SKI IN THE SKY
The business case for a dry ski slope atop the facility wasn't always certain, says Patrik Gustavsson, managing director and CEO, Amager Bakke Foundation, Copenhagen. “Denmark has no real mountains and little snow, and skiing on an artificial surface is something new,” he says. “This, together with the uncertainties of the project, made building a business case a very concrete challenge. Would there be enough people deciding to go skiing? How would users react to the synthetic surface?”
The Amager Bakke Foundation was established to coordinate project funding and oversee ongoing operations of the site. To help build support and ensure residents would engage with a snow-free space, Mr. Gustavsson researched both the number of customers at similarly sized ski slopes and the number of active skiers in the region. A consultancy firm that specialized in sports parks was hired to conduct a specialized feasibility study. Based on that data, it was estimated that between 42,000 and 57,000 visitors might use the site annually, which was enough to win over sponsors.
“A big challenge in the project has been to help all involved stakeholders understand that this isn't an engineering or sports or architectural project alone,” he says. “It's a project that combines a multitude of interests, which requires a holistic approach to design and implementation. The complexity has been tremendous.”
The team collaborated with Mountainworks, a U.S. firm, to settle on the artificial trail's design. To create a smooth artificial slope, the team chose green plastic (meant to evoke the strategic agenda of the project) laid atop grass. The small blades of plastic sticking out of the sheet are coated with silicone to reduce friction, so skiers glide downhill easily.
Meanwhile, the team found subtle ways to incorporate safety features. Any waste management facility must include safety measures for on-site workers who might need to make an emergency exit during operations, but a broader mix of end users meant CopenHill's design plans had to take a much wider lens.
“We had to make simulations of escape routes for ordinary people on the roof—not only for skilled laborers and workers in the power plant,” Mr. Christensen says. That meant adding escape routes and signage along the rooftop recreation area and ensuring such paths could accommodate crowds.
To heighten safety, the facility was also built in such a way that if one part collapses, weight could be distributed to other parts of the structure, allowing enough time for a safe exit. “This has been a key parameter to ensure that the escape routes make it possible to evacuate,” he says.
DPA PICTURE ALLIANCE / ALAMY STOCK PHOTO
PHOTO COURTESY GOTTLIEB PALUDAN ARCHITECTS
SETTING A STANDARD
While discussions were underway in 2012 about new goals for recycling, the government issued a stop-work order. Nine months would pass before final signoffs were granted, meaning the team had to work double time to minimize impact on the final schedule.
“I had one to two months to increase our personnel by approximately 20 skilled engineers,” Mr. Christensen says. “I used my contacts all over Europe to get people I could trust.” He also reallocated engineers from other projects within the firm to help pick up the slack.
But that creative resourcing and adept project planning has paid off for future initiatives. After work on Amager Bakke wrapped up, MOE was able to quickly leverage lessons learned around scheduling and project planning as it constructed a power plant next door. Launched in 2016 and on pace for completion this year, BIO4 will be one of the world's largest wood-chip-powered plants, working in tandem with the Amager Resource Center to deliver heating and power the city.
“It started even before the Amager Resource Center project was complete,” Mr. Christensen says. “But, with a bit of planning, most of the people we used on the Amager Resource Center project could be transferred to this new project.” A win for MOE and a win for Copenhagen's future sustainability. PM
Sten Willer Christensen, project director, MOE
Location: Copenhagen, Denmark
Experience: 38 years
Other notable projects: Piti Power Station, which opened in 1999 on the U.S. island territory of Guam.
Pro tip: Approach project proposals with a critical eye from the start. “We start evaluating the tender material and review the scope in regards to the schedule and quality of the personnel. We don't wait to be awarded a contract to get started, because if you don't look at proposals through a project management lens early enough, you'll move into trouble.”