Bringing an Icon Into the Future: Willis Tower

Few buildings are as iconic as Willis Tower. Generations have a collective memory of this building playing a role in their lives, but time had caught up with this aging supertall. The way the building engaged with the city needed a fresh approach and understanding how Willis Tower is being reimagined by new owners is crucial to the success of old and new supertall towers. Sustainability, façade performance and reducing embodied carbon are at the heart of the transformation of Willis Tower. A new city block-sized podium structure, massive green roof with a grid shell dome, custom solid steel window systems, substantial infrastructure improvements and a façade artwork collaboration with the Olafur Eliasson are part of this case study. The façade design team worked closely with wind engineers to understand how to mitigate stack affects, plan for excessive cladding pressures and avoid pedestrian comfort issues. The resulting open and transparent new podium façade welcomes people in beyond the end of the workday while striking a balance with historic preservation. These are critical factors that go into sustainable efforts to save older tall buildings, many of which are too big to fail or replace from an economic standpoint. This paper and presentation will provide insight into the sustainable façade performance design process, material choices, contractor coordination efforts and challenges for a new benchmark in tall building revitalization.