When it comes to skyscraper design, engineers are often asked to build the “impossible.” But constructing Russia’s Lakhta Center tower—Europe’s tallest building and the world’s northernmost megaskyscraper—required truly creative engineering minds to overcome architectural and environmental challenges of magnitude.

Moscow design company Gorproject designed the 4.3-million-square-foot mixed-use complex, which sits on the Saint Petersburg waterfront. The tower soars 1,516 feet above the Gulf of Finland and will serve as headquarters of Russian gas giant Gazprom. Gorproject CEO Sergey Lakhman, Ph.D., an engineer and designated Honored Builder by the Ministry of Russia, has spent the past 15 years developing his design and engineering business with a specialization in high-rise design.

Lakhman calls Lakhta Center “the most complex object in Gorproject’s portfolio.” This towering anchor of a new sustainable economic center—built to withstand some of the most extreme climate conditions in Europe while exceeding Russia’s rigorous energy and safety requirements (and achieving LEED Platinum certification)—is a bold engineering feat. Here are five of the most impressive design and engineering challenges the Gorproject team faced.

1. Creating Iconic Architecture

Lakhta Center’s organic form consists of five wings that twist almost 90 degrees (0.82 degrees per floor), so none of its 89 levels repeat; this inhabitable sculpture’s extremely complex geometry can only be handled through 3D modeling and Building Information Modeling (BIM) software.

Architectural design, led by Gorproject chief architect and Saint Petersburg native Philipp Nikandrov, was inspired by the city’s historic spires and domes. Nikandrov designed Moscow’s iconic Evolution Tower, another twisting skyscraper by Gorproject. He tapped into that experience and achieved a similar effect through a fabrication process called “cold bending.” Because tempered glass can be safely bent to a certain limit, curtain-wall panels can be shaped into convex curves as they are pressed into frames, forming a smooth envelope. “Cold bending requires far less energy consumption than hot bending, which leads to lower cost and greater sustainability of the building construction process,” Lakhman says.

The Gorproject design team used parametric modeling to optimize the facade panelization in order to increase the number of standard 118-square-foot panels, minimizing costs and reducing installation errors.

2. Achieving Platinum-Level Sustainability

As a global energy company, Gazprom wanted its headquarters to exemplify the LEED standard for sustainability. Gorproject met demanding criteria for energy efficiency, water savings, and recycling, ultimately earning Platinum certification.

The Lakhta Center’s energy-efficient design highlights advanced heating, waste, and lighting systems and an “intelligent facade” that reduces energy consumption. Inside, infrared radiators replace conventional heaters; excess heat generated by the building’s mechanical, electrical, and plumbing equipment is channeled into the heating system.

Rainwater is recycled for irrigation, and the building uses a pneumatic-vacuum waste-disposal system. A computerized LED-lighting system maximizes light energy, inside and out. “Each of the light fixtures consumes 10 times less energy per linear meter than incandescent lamps,” Lakhman says.

Because the Lakhta Center lies in bird-migration routes, Gorproject was tasked with diverting flocks from crashing into its reflective facade. “Birds usually crash into mirrored-glass windows of skyscrapers because, at certain angles, they don’t notice the difference between the sky and its reflection in glass,” Lakhman says. “We proposed quite sparing architectural lighting, which does not blind birds.”

3. Protecting Against Extreme Weather Conditions

Lakhta’s flame-like silhouette (designed to resemble Gazprom’s logo) belies the fact that temperatures in Saint Petersburg hover near freezing seven months of the year. The extreme cold and humidity cause clouds cloaking the 328-foot spire to condense into ice on its surface, presenting a potential hazard of falling icicles. To prevent excessive ice formation, the design team proposed an anti-icing system in the form of radiant mesh-metal plates cladding the spire zone.

With summer temperatures reaching upward of 70 degrees Fahrenheit, weather extremes pose a major challenge for energy-efficient heating and cooling. The building’s double-skin facade is fitted with automatic shutters that provide natural ventilation to prevent overheating of its natural buffer zone between skins. And on sunny winter days, the buffer zone uses the greenhouse effect to reduce heat loads.

4. Ensuring Structural Strength and Safety

In a building that soars a quarter-mile aboveground, fire-protection systems are complex, with all elements—from structural supports to firefighting systems—designed and tested to meet rigorous safety standards. The Center can withstand a four-hour fire without incurring structural damage, and the tower will hold up even if 10 supporting columns collapse.

The project began in 2011, a decade after the 9/11 attacks necessitated safeguards that give building occupants time to evacuate. “We had to ask questions like, ‘How safe will the building be, and will it remain standing if such an impact occurs?’” Lakhman says. To test this, Gorproject created 3D models to simulate scenarios.

The design solution prevents progressive collapse by strengthening impact resistance. “Suppose an impact occurred, and as a result, one vertical-load-carrying element has broken,” Lakhman says. “The building must resist. There can be very large strains on it, and probably after that, it should be rebuilt. But people there should survive and have time to leave.”

Gorproject specified composite steel-concrete columns that provide five times the strength of traditional columns while occupying less floor area. The structural steel forms a sort of hammock: If one floor collapses, floors above and below will be safe.

The tower’s foundation has 264 piles driven 915 feet into the ground and 9,600 tons of metal reinforcement in 15 levels of grids. Fifteen stabilizing perimeter columns redistribute the building’s weight away from the core, so even with wind speeds near the top reaching 85 miles per hour, the skyscraper will remain stable. To keep a constant check on verticality, Lakhman and team designed an automated monitoring system—the first of its kind—using 3,000 sensors installed throughout the building.

5. Making a Smooth Transition to Building Management

After using 2D and 3D technology—including Autodesk AutoCAD and Revit—throughout the project lifecycle, Gorproject passed the BIM model to the owner for operation and maintenance.

“The BIM model was developed with an LOD [Level of Development] of 400,” Lakhman says. “BIM is the toolkit that helped to avoid a large number of serious mistakes during installation. We constantly worked out the geometric conflicts between different elements and systems in the design process. There were so many unique elements—architectural, structural, and engineering—we had to develop more than 6,000 new Revit families.”

The building’s complex facade can’t be maintained using traditional methods, so the Gorproject team literally rethought the concept from the ground up. “Each of the 15 curved ‘petal’ faces of the facade has its own pair of rails on two vertical sides,” Lakhman says. “A trolley travels along each rail, and a telescopic platform is fixed between them, making it possible to compensate for nonparallelism.” The trolleys can support maintenance crews; heavy equipment; and replacement facade panels, which can weigh up to 1,800 pounds.

Ultimately, designing the Lakhta Center was a tremendous challenge—but that’s what the Gorproject team lives for. “When you undertake such an ambitious task that no one has ever solved before, you stop reflecting about your life being in vain,” Lakhman says. “That’s why we in Gorproject try to create objects that can become part of life and make us really alive all the time.”