UN City / 3XN

Architects: 3XN
Area: 45,000 m² + 8,000 m² basement
Year: 2013
Photography: Adam Mõrk
Project Director: Jan Ammundsen
Project Leader: Gry Kjær
Project Team: Peter Feltendal, Simon Hartmann, Søren Nersting (Façade Specialist), Laila F. Feldthaus, Stine de Bang, Pernille Uglvig, Andreas Herborg
Developer: By og Havn
Builder: CPH City & Port Development
Contractor: E. Pihl & Søn A/S
Landscape Architects: Schønherr
Structural Engineering: Orbicon
MEP Engineering & Fire: Orbicon
Manufacturers: CSK Stålindustri A/S
City: Copenhagen
Country: Denmark

UN City, the regional headquarters of the United Nations in Copenhagen, designed by 3XN, unites 11 UN agencies in a highly efficient and secure complex completed in 2013. Its star-shaped form facilitates both autonomy and collaboration, with a central atrium enhancing connectivity and daylight penetration. The headquarters integrates advanced sustainability measures, including a seawater cooling system, rooftop solar panels, and rainwater reuse, reducing energy consumption by 55% compared to similar office buildings. With LEED® Platinum certification, it stands as a model for environmentally responsible institutional architecture, balancing security, functionality, and sustainability.

UN City consolidates multiple United Nations agencies within a single headquarters in Copenhagen’s Nordhavn district, a former industrial port transformed into a vibrant urban area. The Danish government initiated the project to enhance operational efficiency by bringing these agencies under one roof. Designed by 3XN, the building features a distinctive star-shaped form, symbolizing both the independence of each unit and its collective mission. The structure’s layout ensures clear spatial organization while fostering collaboration. Each agency occupies a separate wing, all of which converge at a full-height central atrium that serves as the heart of the building. This atrium allows for visual and physical connections across floors, reinforcing interaction among staff. A sculptural staircase winds through this space, encouraging movement and engagement between departments.

The office design is flexible, supporting various work modes, from teamwork to individual focus. The building’s geometry places all workstations close to perimeter windows, maximizing access to daylight, views of the waterfront, and indoor comfort. The façade incorporates three-meter-long modular panels equipped with perforated shutters, enabling employees to control sunlight exposure from their computers while maintaining external views. Security considerations were paramount, as the headquarters needed to meet stringent international safety standards while remaining accessible. The design successfully integrates these elements, ensuring that security measures do not dominate the building’s character, preserving an open and welcoming environment.

Sustainability plays a key role in the project, reflected in its LEED® Platinum certification. A comprehensive range of energy-efficient strategies reduces environmental impact. The building’s roof features 1,400 m² of solar panels, supplying renewable energy. A seawater cooling system regulates indoor temperatures with minimal electricity use, and rainwater is collected for toilet flushing, reducing water consumption. The roof is covered with a plant-based, recyclable white membrane that reflects sunlight, lowering cooling demands. These features contribute to a 55% reduction in energy consumption compared to similar office buildings, achieving an annual energy usage of less than 50 kWh per m², making it one of Denmark’s most energy-efficient workplaces.

The official inauguration took place on July 3, 2013, attended by Queen Margrethe II of Denmark, Danish Prime Minister Helle Thorning-Schmidt, UN Secretary-General Ban Ki-moon, and other dignitaries. The complex houses 11 UN organizations and accommodates 1,500 employees from 100 different nations. Through its combination of advanced sustainability, security, and functionality, UN City stands as a model for future government and institutional buildings, demonstrating how architectural design can support both environmental responsibility and operational excellence.