These two joining towers are sister buildings made of distinctly different construction systems.  The north tower is made up of a reinforced concrete frame with masonry block and facebrick. The south tower is a steel frame with a similar block and facebrick construction on the lower floors and a glass curtain wall cladding system on the upper floors. The repair program addressed all primary envelope repairs. Bone/Levine Architects assisted in an energy study to evaluate thermal loss and gain of the south tower’s upper curtain walls.