A stately, neo-Renaissance office building from 1915 houses Shell’s headquarters in The Hague, The Netherlands. As part of a largescale renovation, a state-of-the-art structure is welcomed to the premises: one of the monumental courtyards is covered with a gridshell. The dome-shaped gridshell is covered with glass panels cold twisted on-site to reduce the amount of energy combined with a better visual quality compared to warm bended glass.
The glass and therefore grid size is defined as a result of a meticulous, parametric game: the perfect balance is sought between maximal stiffness for external load and minimal stiffness for cold twisting of the glass. This exercise increased the grid size from 1.6m to 2.6m reducing a large amount of material.
Where old meets new, challenges arise: no forces can be exerted perpendicular on the perimeter of the monumental courtyard, resulting in sliding connections in a horizontal direction. Moreover, during installation the structure may not rest on the scaffold. This brought another challenge to the table, as the only remaining connection to the existing structure is the ring beam. For this reason, the roof is divided into the largest possible self-spanning frames, with the limiting factors of transport and coating in mind. After installing these frames, in the centre of the roof a square-shaped gap of 21x21m remained that was filled up with a reciprocal frame division, installed with two cranes simultaneously.
