Rathaus der Zukunft – City Hall of the Future

Client: Berlin City Hall

Location: Berlin, Germany

Date: 2024

Type: Civic

Area: 20184m2

Budget: €185.12 million

AZPML

Alejandro Zaera-Polo, Maider Llaguno-Munitxa, Ivaylo Nachev

Studio Witt

Jan Pietje Witt

General Aims

The building has three primary ambitions:

1.To provide connectivity across all departments to enhance synergy between them and with the public.

2.To create a structure maximum flexibility so that the building can accommodate programmatic changes in the future.

3.To achieve maximum sustainability through the compactness of the building mass and the adoption of a low-carbon materiality: timber.

Urban and Architectural Performances

The building has two very distinct sides:

1.One pointed to Otto-Braun Strasse and the NW, presenting a big-city architecture regular window pattern and a 40% window ratio on a well-insulated envelope, which wraps around the SW and NE sides, which step down toward the SE. The envelope will be built using technical terracotta ceramics, reminiscent of the Berlin brick buildings. The terracotta ceramics are designed with a ribbed motif which will provide finesse to the detail. The socle will be clad in granite like in the Berliner tradition. Windows will be triple glazed and natural ventilation will be available through traps on the side of the windows to simplify the detail and reduce air leakage.

2.Another side will be pointed toward the SE and the Stadtzimmer, and will be built as a tilted, single glazed envelope, with embedded PV-cells, which will maximize solar intake while enclosed a terraced and vegetated atrium connecting all programs, and linking the ground level public space with the rooftop public greenhouse.

Overall Concept

Our proposal for the future Rathaus in Berlin Mitte is aimed to provide a landmark building which will engage with Berlin’s Groβstadt Architektur lineage, while providing an open infrastructure open and capable to engage the public. The building has been designed as a very compact, single mass, organized around a central atrium which will provide visual and physical connectivity between the different departments, while acting as a thermal regulator and air-circulation inducer. In the summer, the atrium will act as a natural ventilation engine, making the air move upwards through buoyancy while extracting the air from the rooms naturally. In the winter it will act as a thermal buffer where the air will be naturally heated by the greenhouse effect.

The building includes 13 levels of administrative and public program with one level of technical facilities, and is crowned by a public greenhouse where citizens can access freely as a viewing point and a resting space.

The program is organized around a vertical atrium located on the south side of the building plot.

Atrium as a public space and as environmental regulator

The vertical atrium will create a collective space shared between all departments and the publicly accessible facilities, while acting as an environmental regulator: it will act as a solar collector in winter, using greenhouse effects to naturally temper the interior space, and in summer it will act as a ventilator through buoyancy, which combined with evapotranspiration from the interior vegetation and with water sprays, will contribute to lower the temperature of the public space. An open stair located in the atrium will also foster the connectivity between departments, which can be easily connected through an open stair.

The top floor will feature a “Tempietto” type greenhouse which will be used for weddings and public events.