FOUR Frankfurt is a large-scale mixed-use development redefining the former Deutsche Bank site in the heart of Frankfurt’s banking district. Developed by Groß & Partner, the project introduces a compact, vertical urban ensemble composed of four high-rise towers with differentiated functions and façade strategies. The architectural concept is led by UNStudio, while HPP Architekten is responsible for approval and execution planning, ensuring continuity between design intent and technical delivery.

The tallest structure within the ensemble, Tower 1, reaches a height of 233 metres and represents the most technically advanced façade package of the development. Primarily designed for office use, the tower adopts a unitised double-skin façade system, selected to address energy performance, user comfort, and regulatory requirements in one of Europe’s most demanding high-rise environments.

The confirmed façade scope for Tower 1 includes approximately 29,800 m² of unitised double-skin façade elements, supplemented by around 1,150 m² of post-and-rail façade areas and 2,700 m² of additional cladding zones. Fabrication and installation were delivered by Dobler Metallbau, with façade installation taking place between February 2022 and June 2023. Within the wider FOUR Frankfurt development, façade responsibilities are clearly divided: Dobler Metallbau executed the façades for the office towers, including Tower 1, while Josef Gartner was commissioned for the façades of the residential towers.

Façade engineering and performance consultancy for Tower 1 was carried out by Priedemann Fassadenberatung, supported by SGS, reflecting the project’s strong emphasis on façade performance, safety, and long-term operational efficiency.

The double-skin façade is composed of factory-assembled elements integrating multiple functional layers into a single unit. The outer skin consists of heat-strengthened glass (TVG), acting as a protective weather and impact layer. The inner layer incorporates triple-glazed units, providing high levels of thermal insulation and acoustic comfort. Integrated roller blinds are housed within the cavity of the double façade, enabling effective solar control while remaining protected from external exposure.

Ventilation is achieved through full-height ventilation grilles positioned adjacent to the glazing, rather than conventional openable windows. This strategy supports a controlled indoor climate and aligns with the building’s low-energy operational concept.

From a systems perspective, the façade utilises Schüco aluminium solutions, with the double-skin construction based on the Schüco AWS 75 platform. In selected areas, the façade combines Schüco FWS 60 curtain wall construction with the ASE 80 TC thermally insulated sliding system, enabling large glazed openings while maintaining performance targets.

The project also integrates approximately 600 fire and smoke protection door units across the four towers using Schüco ADS 90 FR 30 and FR 90 systems, supplied by RFE Rauch- und Feuerschutz-Elemente. At roof level, Tower 1 features standing-seam aluminium cladding executed with BEMO aluminium systems in an anthracite finish.

FOUR Frankfurt stands as a clear reference for contemporary high-rise façade execution in dense European urban contexts, where envelope design, system integration, and performance engineering are central to architectural and operational success.