Achieving sustainability through a cyclical process of evaluation and adjustment: a support system for urban design

This paper investigates the possibility of making visible what is usually invisible in the urban design conceptualization phase. An evaluation system, constituting a basic guide for the assessment of sustainability for urban design projects, acting both on the existing and the new fabric, is presented here. The proposed system translates the complex social and physical systems into measurable units of information, thus making them visible to decision makers. In particular, this work explores the concept of evaluation as a support tool for urban design; for instance, the results of the application of some indicator methods can be useful for representing themes that are crucial for assessing the sustainability of urban design projects. The study starts with the construction of a system of urban sustainability indicators by exploring the concept of assessment as a tool to support the communication of sustainability of urban design. Currently, numerous environmental certification and evaluation systems at the urban or district scale are available. These tools, starting from a set of criteria and indicators inspired by the model of a compact and efficient city, aim at guiding the urban design process. These indicator systems try to respond to challenges emerging from the complexity of the city. The focused use of sustainability indicators at the scale of neighborhood design (master-planning) allows the conceptualization of the design process in an action space of n dimensions, Mere n is the number of indicators chosen for this purpose. The indicators are selected according to the objectives, which can be identified by policy needs, by stakeholders or by the people to ensure the improvement of the quality of life. Urban transformations are played within complex environmental dynamics, so it is impossible to define a priori the space of action. Hence, it becomes necessary to consider the design as a process of continuous adjustment derived from the available design altematives: in fact, the design process reveals itself to be a navigation between small portions of that area in respect of Mich it is possible to evaluate different design altematives. For instance, it is possible to outline a generic situation with two criteria (cl and c2) and four altematives (a1, a2, a3, a4). In the research of the space of action, it is possible to have two directions for its modification: (1) modification of the set of criteria, (2) modification of the set of alternatives. Hence, this paper proposes an approach to design as a cyclical process of evaluation and as an adjustment of different project solutions, such as an exploration of the space of actions. In particular, this paper presents at first a system of urban sustainability based on indicators, which are derived from existing evaluation systems. Then, the system is applied for evaluating three different design proposals for the retrofitting of a social housing district from the 30ies located at the periphery of a European city. These alternatives allow to identify the portion of space of action in respect of which the process of evaluation and subsequent design can start.