Stoffwechsel

The text describes some aspects of Semper’s Stoffwechsel theory (Stoff: material, wechsel: change) the meaning it had and has for the architectural debate. The transition from nomadic huts and tents to stone Architecture, from the wooden temple to the temples made to last forever, and in general all the passages of “replacement transfiguration” have marked the milestones in the history of Architecture, announcing turning points, changes of paradigm, technological revolutions, nowadays the reinforced concrete that deeply affected our way of building, suggesting a new relationship between civil Architecture and monument. The Stoffwechsel theory is not understandable if we do not consider it together with the other great theoretical contribution of Semper, the Bekleidungsprinzip (literally: the closing principle). For Semper, Architecture is made of core and envelope. But while the envelope can change to accommodate the epochal, cultural and technological innovations, the core and its spatial laws remain unchanged. It is the space generated by the structure that represents the stable and permanent element. Semper’s attention in his writings highlights the envelope. It is one of his contemporaries, the historian Gustav Schmarsow who, with controversial arguments against Semper, unexpectedly proposes the interpretative key to understand the mutual relationship between space and structure. The Cartesian space that gives order and rationalizes man’s work, represents the immutable principle of Architecture. It is a principle that is found both in the shelter as well as in the monument. It is the materials and proportions that make the difference. The core remains unchanging. This is demonstrated by Mies van de Rohe’s invention of the curtain wall, which dematerialises the envelope baring the space it contains. In the illustrated examples, very different buildings are compared, starting from the Maison Dom-ino. In each example the structure is highlighted as a lowest common denominator. The paper ends with the comparison between an office building in Belgium and the multipurpose building of an Indian Academy. Both spaces are defined by the pattern of regular pillars and delimited by a transparent glass envelope in the Belgian design and by the semi-transparency of a bamboo trellis in the Indian design. The envelope is the variable element that gives the building its character and appearance. The structural distance between the pillars and consequently the space it contains is the same. In this comparison, the principle of universal space generated by the structure becomes evident.