Eco-design decision making : towards sustainable engineering design of large made-to-order products
Sustainable design provides an holistic, life-cycle approach by which design engineers can minimise negative impacts and maximise positive impacts, thus ensuring that current industrial progress is not achieved at the expense of future generations. In the context of sustainable design, large made-to-order (LMTO) product sectors must address some unique issues: " The design process may be in the order of years, involving the client, the design contractors, co-venturers, suppliers and regulators. 9 The one-off nature of the design may limit the opportunity for reuse of design knowledge. 11 The existenceo f the possibility of catastrophico ut-of-envelopee ventsl eading to large scale safety and environmental impacts. " There is potential for high energy and resource consumption. " . Some LMTO products may cause local and transboundary environmental impacts. 0 There may be long term, post-decommissioning impacts. 0 Some aspects of the product life-cycle may give rise to impacts on social welfare. Engineering design is a process of decision making both during option synthesis and option selection. The first part of this research examined the current integration of environmental objectives and attributes with industrial design decision making processes using qualitative research methods. In particular, design selection was considered as the case-study focused on the activities of two case-study design contractors. The second part of the research proposed a framework to assist the consideration of environmental and societal impacts using transparent, systematic methodologies based on Multiple Attribute Decision Making (MADM) approaches. Two MADM methods were compared in relation to a case-study regarding the selection of an option for a produced water treatment system; Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Concordance and Discordance Analyses by Similarity to Ideal Solution (CODASID). Due to the subjectivity and uncertainty associated with information relating to sustainable design, a fuzzy set-based methodology was also investigated. In order to simulate the intuitive processes of human decision makers, the application of linguistic terms to evaluate sustainable design attributes was explored. This method was applied to a group decision making case-study to determine the best option for replacing a heat exchanger situated in a pond water cooling system. Comparisons were made between the fuzzy MADM method and the decision obtained from a group-based discussion. Finally, the third part of the research specifically addressed perceived risk attributed by the public to proposed large made-to-order products or processes, accommodating the societal element of sustainable design. Public risk perception was decomposed into measurable indices which were suitable for application to the fuzzy MADM method. The final aggregated evaluation, representing the overall perceived risk associated with the product in question, was then examined under different tolerance scenarios in order to make an informed judgement with respect to product viability. These three core research elements provide the foundation for managing the environmental and societal aspects of sustainable engineering design of large made-toorder products, thus providing an important addition to the wider concept of integrated product design.