Value evaluation of eco-products for design decision support

Abstract

Designing environment-friendly products, known as eco-products, has become an essential practice in many manufacturers mainly due to increasing consumer awareness to the environment, governmental regulations and marketing strategies. Most of the scientific literature on eco-product design deals mainly with the improvement of the environmental performance. Engineers and eco-product designers need large quantities of information for evaluating environmental performance of eco-products. However, other considerations relate to the creation of eco-products should not be overlooked, such as product form aesthetics and functionality. This research moves beyond technical evaluations of environmental performance of eco-products by developing a new design decision support approach for evaluating the eco-product value (EPV) as perceived by consumers. To do so, this research develops a new approach using Kansei engineering, neural network (NN), and multiattribute decision making (MADM) methods in order for product designers to achieve optimal eco-product form design based on combinations of EPV attributes. An experimental study on office chairs is conducted to illustrate how the EPV evaluation model can be developed and used to evaluate the value of a given eco-product. The Kansei engineering method is used to translate consumers’ feeling of the office chair into product form elements, and help product designers understand consumers’ perception. Product samples are collected from 100 collected office chairs by using multidimensional scale and cluster analysis, by which 27 representative office chairs are chosen for the consumer-oriented experiments. Morphological analysis is used to extract 7 design elements as well as 20 types of form components. In addition, the value of eco-products is measured by three dimensions, characterised by aesthetic, functional, and environmental attributes, which are derived from both the literature and expert product designers. The aesthetic, functional and environmental dimensions consist of 7, 3 and 5 perceivable EPV attributes respectively. Each EPV attribute is assessed through a consumer-oriented experimental process. Results of Quantitative Theory Type I analysis have indicated the relative importance of office chair form elements to EPV attribute images. To enhance the applicability of this approach, NN models are applied for providing a mechanism to support the eco-product design decision making process by establishing a database of design alternatives. Then, MADM models are used to obtain the value of a given eco-product with weighted design attributes in an EPV evaluation model, which integrates both the consumer’s and designer’s viewpoints as a whole. The best design decision for a given design setting has a maximum weighted value among all design alternatives. In addition, the correlation between EPV attributes and eco-product form image is analysed by using Pearson correlation analysis to the product form image word pairs and EPV attributes. The result shows a weak non-linear relationship between EPV attributes and product form images. As such, eco-product designers can consider these two variables separately when designing eco-products. The value evaluation approach developed in this research is novel in that the target eco-product design parameter is the consumer perceived EPV which is measured in aesthetic, functional, and environmental dimensions. This is different from existing techniques for eco-product design and evaluation. The approach is verified through an application to office chair design for emphasising environmental perception. Specifically, office chair design sketches are developed based on the result of MADM analysis. The outcomes of this research have a great potential for solving practical EPV selection and ranking problems by applying the EPV attribute weights given by the product designers. Various experimental results can be used as insightful guidelines for selecting an eco-product from product form design element combination for a given EPV attribute.