The Princeton Envelope Group (PEG) is a design and research unit at the Princeton University School of Architecture. Headed by Alejandro Zaera-Polo and coordinated by Urtzi Grau. The unit is engaged in a three year research program on the Politics of the Building Envelope the conclusions of which will be published in a forthcoming book by Actar Press, Barcelona+New York.


Diagram compares the footprint, occupiable floorplate and naturally lit floorplate for existing towers: Taipei 101, Commerzbank, Petronas Tower, Lippo Tower, Torre Agbar, Chicago Spire, Marina City, Aqua Tower,Silver Towers, 860 880 Lakeshore Drive.

This graph shows the relationship between floorplate area and facade ratio for towers with different footprint shapes. All the curves assume a 3.3 meter floor to floor height typical in residential tower construction. The points represent existing towers showing how real life cases correspond to the idealized model. The circle is the tower footprint with the smallest facade area per unit area of interior. As shapes become more elongated or corrugated the facade ratio per unit area of interior increases.