City Palace, Humboldtforum, Berlin, Germany

In 2016 Bildau & Bussmann was awarded the project of planning and manufacturing windows for the reconstruction of the historical portal facades of Berlin's City Palace.

There are box casement windows, each consisting of an exterior and interior window. The exterior window meets the aesthetic needs of the historic facade, while the interior window is built to fullfill all insulating and security requirements of a modern museum building.

The windows are up to 5 m (16' 4") wide and 9 m (29' 6") high, with surface areas of up to 45 m² (484 ft²) per element.

To withstand the enormous wind loads that such large window surfaces are subject to, the windows are reinforced with structural steel. To maintain the historical look of the exterior, these reinforcements are concealed within the wood profiles. Up to one ton (2.000 lbs) of steel was built into a single unit.

Additionally, Bildau & Bussmann was in charge of the entire production planning and implementation. A team of six engineers worked together on this for over a year.

The planning and manufacturing of the portal windows for the Berlin City Palace is considered one of the technologically most challenging and ambitious current window projects in Europe.

Cross section mezzanine arched window

Depiction of opening functions and steel reinforcements