Evaluation Method of Design Products Based on Eco-Efficiency

Abstract

Evaluation methods of Environmental burdens have been improved. Some of those methods indicate intensity of environmental burdens in money unit to make them comparable to production cost. Moreover, from sustainability point of view, improvement of functions is as important as reduction of environmental burdens. Namely, environmental burdens and functions have to be balanced. Therefore, we aimed to develop the evaluation method of design products that is able to optimize balance between them. We had developed the evaluation method of environmental burdens, which indicates potential of economical loss caused by environmental impacts and defined it as Societal Cost. This is used for evaluation of environmental burden. In this paper, we improve this method by adding the Function Value. To compare the value of functions with environmental burdens, every evaluation criterion has to be integrated in single score, and it is desired to be money unit. We derived value of functions by using the information theory and defined it as Function Value. Eco-Efficiency Index evaluates products. This is based on the concept of Eco-Efficiency and calculated by dividing Function Value by Societal Cost. Societal Cost: Pollutants cause many environmental impacts and many kinds of losses through their lifetimes, and most of them can not be converted into money except the loss of productivity. Societal Cost indicates the social loss of productivity by the decrease of human health caused by the increase of disease or disaster originates on emission of pollutants. Function Value: To evaluate products’ value in single score, value of each functions existing in product has to be quantified and integrated. The information theory is applied for this method. Amount of information of each function is derived from probability of satisfying consumer. However, functions have different importance. Therefore, amounts of information of functions are added up after weighted by Relative Importance of each function, which is determined by using QFDE. We defined it as Integrated Amount of Information. It is also important to think the span of utilization. To express the relation between product’s value and time in use, three types of depreciation methods are applied. They should be chosen in accordance with aging characteristics of product. Eco-Efficiency Index: Eco-Efficiency Index is defined as Function Value divided by Societal Cost. This definition is based on the concept of Eco-Efficiency advocated world wide, which mean obtained value per unit amount of environmental burden.