Digital Mockup: Steps into the definition of a Friction-Joined System for a Responsive ETFE Façade for Highrise Buildings Daniel Cardoso, Dennis Michaud Abstract Figure 0. Waterjet Cut models of two Façade Systems The inclusion of technological devices in the built environment may eventually have a profound influence on architecture and may lead to new design philosophies that solve tectonically the dialogue between traditional materials and computer networks; this document describes an exploration on a façade system that articulates distributed network computing and flat-cut, friction-joined architectural elements in order to improve the energy-efficiency, flexibility, and visual quality of a high rise building. The exploration takes advantage of the material properties of ETFE foil and of the processing capabilities of a micro-computer unit network in order to propose a new kind of implementation of electrochromic smart windows that allows for changing opacities of the façade elements in response to human touch. An investigation on design tools and the role of physical representation in the design process itself, the work described in this document was developed using a variety of rapid prototyping tools and CAD software. Physical prototypes and plans of two different designs for the system are presented and discussed, followed by a 1in = 25ft scale physical representation of a larger implementation of one of the details along a verisimilar high rise building. The varied range of representations allowed for a critical evaluation of both systems at different levels, contributing to the understanding of the constraints inherent to two-dimensional friction joint assemblies, and revealing problems related to detail representation in rapid prototyping models. While providing a review on electrochromic smart windows and distributed network computing technologies we outline the fundamental principles of a new system that uses ETFE cushions instead of glass as the base for touch-responsive electrochromic smart windows; the study presented in this document proposes a series of discussion points around the use of combined physical and virtual representation strategies in architectural design.1 Introduction Façade systems are to a great extent responsible for both the energy-performance and overall aesthetic qualities of a building. ETFE cushions have been largely used by architects since the 1980s as an alternative to glass because of their similar transparency, higher thermal isolation properties, and energy- and cost-efficient assembly and production processes (Robinson-Gayle 2001). Architectural applications of this material are in most cases roofs for large atria and other big-scale spaces, showing ETFE cushions to be a viable alternative to traditional glazing. In recent years architectural thinking has been concerned with the pervasive presence of electronic devices and information networks as important components of urban space. This concern has led many architects to see the overlaying of digital technologies on buildings as a relevant design problem, and thus some have begun to seek for a deeper understanding of these technologies in order to integrate them within architectural practice (Manovich 2000). Recent works of architecture such as the Prada Store by Rem Koolhaas, Jumpcuts by Diller + Scofidio (Figure 1), and NYSE Trade Floor by Asymptote Architecture (Figure 2) strive for an aesthetic integration of communication networks and electronic displays within their buildings. This integration between physical space and electronic media, however, occurs only on at the surface level, as these projects use electronic devices merely as digital fixtures that are superimposed on a traditional architectural structure. This study examines the tectonic integration between computer networks and architecture through the application of ETFE cushions on the façade of a high-rise building, exploiting the soft nature of this material in order to embed an electronic network that provides functionality and touch-responsiveness in the façade. As a first step, an architectural reading of Renzo Piano Workshop’s New York Times Headquarters provides us with some of the main arguments that give form to our system; second, we present the design and further evaluation of two different friction-joined systems developed using different software and fabrication techniques; third, the implementation of one of these systems in a larger scale model within a verosimilar architectural context. Parallel to these, a basic review of MCU technology and of the smart windows technology allows us to assess the technical feasability of the system. The final sections examine the generality of the results and suggest some discussion points on the implications of the work regarding two aspects: • The touch-responsive electrochromic smart pillows as integrated elements of a high-rise building. This issue can be reduced to the following questions: a) Does the inclusion of a network of computers inform the design process with new variables and considerations? b) What are the implications of using ETFE on high-rise buildings? And c) Is it actually possible to create a touch-responsive smart ETFE pillow? • A critical view of the design process as related to the different software and rapid prototyping tools used. This issue can be summarized in the following questions: a) How does the problem of scaling for digital fabrication affect the design process? and b) What were the major implications of using a parametric software package in2 the development one of the designs and a more “traditional” CAD system in the other? The goal of this document is to shed light on to these questions. Image removed for copyright purposes. Figure 2. Diller + Scofidio’s Jump Cuts in Venice California Image removed for copyright purposes. Figure 3. Asymptote Architecture’s New York Stock Exchange Floor, from http://www.asymptote.net Piano Lessons We identified some of Piano’s building most relevant attributes in terms of the visual aspects of the façade solution: • Horizontality • Color quality (related to thermal performance) • Transparency And some technical attributes as well: • Light – Heat Performance • Standardized small scale components Here are some of the design considerations and learned lessons from Piano’s façade. • The changing distance between rods throughout the façade