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.


The spherical envelope’s dimensions are approximately equivalent in all directions; cubic, spheroidal, and polygonal geometries are also particular cases in this category. In principle, the spherical envelope has the lowest ratio between its surface and volume it contains. The specificity of this type is the relative independence that the skin acquires in relation to its programmatic dterminations, as functions are not strongly determined by adjancency to the outside and, therefore, by the form of the envelope. This often implies a wider variety of programs inside and a hetrogeneous environmental content. Spherical envelopes generally enclose a wide range of spatial types with specific functions, rather than a single spatial condition. Unlike other envelope types in which the border between public and private occurs on the surface of the container, the spherical type often contains gradients of publicness. Spherical envelopes often correspond to public buildings that gather a multiplicity of spaces, such as city halls, courthouses, libraries, museums, and arenas. In the spherical envelope the gap between expressive and environmental performances is at a maximum, with low environmental and high expressive performances.