The concept of the public and the private spheres has structured the life of cities and societies, delimiting zones for different behaviours, individual and collective. The borders between those spheres are one of the most important tools of political and social organization that a community may use, and their performance has evolved historically to suit particular distribution of power. In the age of globalization, the redefinition of these categories and the determination of the limits between them is one of the crucial processes taking place in our cities, to which architecture and urbanism can effectively contribute.
With the current issues of energy preservation and security affecting architecture, there is a tendency towards opaqueness where the border between inside and outside, private and public will become increasingly reinforced. The sharpening of borders and the homogenization of interior spaces is the most immediate outcome these pressures on the envelope. On the other hand, the process of privatization -and now nationalization- points at an alternative tendency towards an increasingly tenuous threshold between public and private domains. The contradiction between these two tendencies is likely to increase the complexity of the membrane in response to the redefinition of the relationships between the body and the face of the building and its surroundings. The envelope as a device to homogenize content versus differentiate and draw external links may draw discussions of the limit between Public and Private linked to Democracy vs. Totalitarianism and Economy vs. Politics.