Co-Auteur I/O WALL: INTERACTION DESIGN THROUGH ASSOCIATIVE PARAMETRIC MODELING David Gerber Southern California Institute of Architecture Mark Meagher Ecole Polytechnique FØdØrale de Lausanne Jeffrey Huang Ecole Polytechnique FØdØrale de Lausanne 0. Abstract While the disappearing computer offers a compelling vision for the future of human-computer interaction, its reality de- pends very much on design decisions made at the level of the architectural detail. This case study outlines a series of design proposals developed to explore the formal and tec- tonic implications of embedding computer hardware and functionality in building interiors. Students in two studios at the Southern California Institute of Technology were asked to design a wall of shelves capable of detecting and displaying patterns in the use of the shelves and surrounding spaces over time. The goal in both studios was to imagine new forms for the building interior based on the dimensions, range, optimal spacing, and other characteristics of the embedded computer hardware (sensors, microprocessors, and LEDs), as well as on the interactive potential of the wall. Each student project resulted in a prototype interactive system which is parametri- cally defined for fabrication and for future reconfiguration. The design proposals were evaluated according to a set of criteria that we established to assess the effectiveness of the parametric system and the success of the form as a mapping of the interactive capabilities of the building interface. 1. Introduction 1.1 Building Interfaces The integration of computer functionality in the built environ- ment is already becoming commonplace, both in the home and in contemporary institutional buildings. Networks of sen- sors are used to monitor temperature, humidity, and carbon dioxide levels in the air; solar radiation on the facade; and the presence of building occupants. This information can then be used to optimize the effectiveness and efficiency of building environmental systems, to time the raising and lowering of operable sunshades, and to automatically open doors as peo- ple approach them. Standards are being developed for wire- less [1] and wired [2] communication between controllers and input/output (I/O) devices such as sensors, automated building components, and information displays. The integration of I/O devices in the building has provided architects with a new range of tectonic expression, particu- larly in the articulation of output devices and the temporal variation that they can bring to the building interior and the building envelope. The 1988 Institut du Monde Arabe building by Jean Nouvel in Paris is one early example of a computer output device  the motor-controlled diaphragm sunshades on the faade  that is enabled to become a highly expressive architectural element. The tectonic expression of the mo- torized diaphragm and its dynamic response to seasonal and daily changes in the environment is both a reinterpretation of a traditional element in Islamic architecture (the mashrabiya), and an iconic representation of the building and of its function as a center of Islamic culture [3]. Many other buildings since the Institut du Monde Arabe have explored this capacity of computer output devices to pro- vide a dynamic tectonic expression of computer-controlled functionality. The types of output devices used have ranged from motorized faade elements (the transparent glass lou- vers of Jean Nouvels 2004 Torre Agbar Headquarters) to