The 300-metre Commerzbank Tower in Frankfurt, designed by Foster + Partners and completed in 1997, is celebrated in the glass industry as a pioneering example of double-skin façade technology. Its envelope showcases how architectural glass can deliver transparency, performance, and sustainability in a high-rise context.
The façade features two distinct glass layers. The outer skin is composed of single toughened laminated safety glass, approximately 8 mm thick, installed as planar glazing. This layer acts as a protective barrier against wind and rain while maintaining a crystal-clear, low-iron transparency that maximises daylight.
The inner skin uses full-height, double-glazed insulated units with low-emissivity (low-E) coatings. These units balance thermal performance with optical clarity, reducing heat loss in winter and limiting solar gain in summer. Many are operable, allowing occupants to manually control fresh-air intake.
Between the skins lies a 200–252 mm ventilated cavity. This space houses solar-control blinds, sheltered from weather yet optimally positioned to cut glare and heat. Ventilation slots at the top and bottom of the cavity enable natural airflow through stack effect principles. 
Fabricated by specialists including Josef Gartner GmbH and recorded in Permasteelisa Group’s historic portfolio, the façade remains a reference project for glass engineers worldwide. Its integration of laminated safety glass, insulated glazing, and controlled cavity ventilation helped redefine glass’s role from passive cladding to an active environmental system.
Source: Glass Balkan
