Abstract
The contemporary manufacturing organisations recognise sustainability as an important concept for survival in the competitive scenario. Sustainability addresses triple bottom line namely profitability, people and planet. The concept selection in the context of sustainability is a typical multi-criteria decision-making (MCDM) problem. The case organisation needs to select the best concept among five concepts which are used to infuse sustainability during early product design and development phases. The decision-makers of the case organisation felt that technique for order preference by similarity to ideal solution (TOPSIS) is the appropriate MCDM technique for sustainable concept selection. The decision-makers' inputs have been gathered and the various steps in TOPSIS have been executed. Based on the distance of each concept from ideal and anti-ideal solutions as well as on the basis of closeness index, the concept Environmental Conscious Quality Function Deployment is found to be the best concept. The selected concept has been subjected to implementation. The results derived from the study indicated that TOPSIS is an effective approach towards sustainable concept selection.
Nomenclature
| x ij | = |
aggregated fuzzy performance ratings |
| W j | = |
importance weights |
| U | = |
fuzzy decision matrix |
| W | = |
weights matrix |
| R | = |
normalised decision matrix |
| V | = |
weighted normalised fuzzy decision matrix |
| I + | = |
ideal solution for each concept |
| I − | = |
anti-ideal solution for each concept |
|
| = |
distances of each concept from the ideal solution |
|
| = |
distances of each concept from the anti-ideal solution |
| c i * | = |
closeness coefficient |
Introduction
Sustainability is regarded as a key concept for survival in the competitive market. Sustainable manufacturing involves the creation of products that deploy processes with the objective of minimising environmental impacts, thereby conservation of energy, natural resources and safety aspects for stakeholders could be ensured. The three orientations of sustainability include material, product and process. Concept selection in the context of sustainability is a typical multi-criteria decision-making (MCDM) problem. Some of the MCDM tools include analytic hierarchy process (AHP), analytic network process (ANP), preference ranking organisation method for enrichment evaluations (PROMETHEE), Elimination and Choice Expressing Reality (ELECTRE), VIKOR (VlseKriterijumskaOptimizacija I KompromisnoResenje in Serbian, meaning multi-criteria optimisation and compromise solution), technique for order preference by similarity to ideal solution (TOPSIS), etc. In the present study, TOPSIS has been used for the selection of best sustainable concept. The reason behind the selection of TOPSIS is that it considers both ideal and anti-ideal concepts and is one of the most popular MCDM methods. In the present study, fuzzy TOPSIS approach proposed by Tsao and Chu (Citation2002) has been used. Five concept designs have been analysed from the perspective of sustainability among several sustainability criteria. The objective of the study is to select the best sustainability concept for implementation considering several sustainability criteria. The best concept has been subjected to implementation in the case organisation. The results derived from the study indicated the practical feasibility of deploying TOPSIS for sustainable concept selection in real-time manufacturing scenario.
Literature review
The literature has been reviewed from two perspectives of sustainability and MCDM applications in sustainability.
Literature review on sustainability
Yan et al. (Citation2009) have mentioned a shift in importance in manufacturing or marketing to sustainability in providing design services, such as economic, environmental and ethical issues, in several multinational companies and small- and medium-scale industries. They have attributed this shift to cost reduction incentives, legislative pressures, marketing strategies and environmental policies. The authors have mentioned that using sustainable product design, environmental impacts are reduced and business benefits cover a global view of design chain, optimisation of design process, customisation of methods, encouragement of creativity and cooperation of customers and suppliers. Gungor and Gupta (Citation1999) have elaborated upon the importance of environmentally conscious manufacturing and product recovery (ECMPRO) with respect to environmental and social issues. The authors have mentioned that ECMPRO is enforced primarily by governmental regulations and customer perspective on environmental issues due to the escalating deterioration of the environment, such as diminishing raw material resources, overflowing waste sites and increasing levels of pollution. Walmsley (Citation2002) defines sustainable development as a kind of development that aims for equity within and between generations, and adopts an approach where the economic, social and environmental aspects of development are considered in a holistic fashion. Wien and Binder (Citation2005) have developed a sustainability assessment tool for city regions. The authors have presented an approach to construction of sustainable solution spaces for decision-making (SSP). The authors have concluded that the proposed tool for constructing an SSP satisfies the requirements of an appropriate sustainability assessment, considering (i) normative aspects such as goal orientation, consistency and flexibility; (ii) systemic aspects such as simplicity, representativeness, parsimony and sufficiency; and (iii) procedural aspects such as transdisciplinarity. The authors have expressed the need for further research: first by empirically testing the tool, second by integrating the tool into a comprehensive planning framework, and finally by combining it with scenario analysis, multi-attributive evaluation tools and strategic planning methods. The authors have mentioned a third task of applying the tool to political decisions to determine whether they contribute to sustainable development or not. Marksberry and Jawahir (Citation2008) have developed a method to predict tool-wear/tool-life performance in near-dry machining (NDM). NDM is a sustainable process that has minimised the use and application of metal working fluids (MWF). The method is developed by extending a Taylor speed-based dry machining equation to include mist spray delivery parameters by modifying the tool coating effect factor. The authors have concluded that using mist spray applications can be successfully and more accurately predicted than using dry machining equations for NDM. The authors found that equation accuracy over a broad range of MWFs, nozzle position(s) and MWF volumetric flow rates was observed to be less than 10% on the average. The authors have emphasised that models developed for dry machining conditions cannot accurately predict NDM performance. The authors have mentioned that the new tool-wear/tool-life equation should be validated for a wider range of conditions including atomisation type, chip form/flow interference with spray mist field, cutting geometry and work materials than has been done in their study. Vinodh and Rathod (Citation2011) have applied Environmental Conscious Quality Function Deployment (ECQFD) to enable environmentally conscious design and sustainable development in an electric vehicle. The authors have applied ECQFD to determine the most effective electric vehicle design with regard to environmental improvement. Using ECQFD, the authors have proposed a design according to which changes were made to affect environmental consciousness at the early stages of the electric vehicle. The authors have expressed the need to modify the framework of ECQFD to enhance its effectiveness. Tseng et al. (Citation2009) have evaluated the performance of synthetic sustainable production indicator (SPI) in a multinational original equipment manufacturing firm. The authors have adopted fuzzy measure and ANP method to evaluate the performance of the synthetic SPIs. The authors have concluded that the products are the most important criteria, and other important criteria include reducing amount of hazardous waste generated, increasing the use of energy from renewable sources and reduction of waste generated by contracted service/material providers. Lauren et al. (Citation2010) have used carbon footprint as an environmental performance indicator for the manufacturing industry. The authors have used life cycle assessments (LCA) of several materials of major relevance to manufacturing industries to evaluate the ability of carbon footprint to represent the overall environmental impact. The authors have concluded that carbon footprint cannot be taken to represent the overall environmental impact due to the large variations observed among the type of material and the type of production, and the poor correlation between carbon footprint and human toxic impact. The authors have mentioned that the applicability of carbon footprint as an indicator of environmental sustainability in the design and manufacture of products needs to be documented on a case-by-case basis.
Literature review on MCDM applications in sustainability
Chiou et al. (Citation2005) have evaluated strategies for sustainable fishing development. The authors have used the non-additive fuzzy integral approach to construct an evaluation framework using AHP. The authors concluded that non-additive fuzzy integral is an effective approach and is more appropriate than the simple additive weighted method. Gervásio and da Silva (Citation2012) have developed a probabilistic decision-making approach for the sustainable assessment of infrastructures. The authors have used PROMETHEE and AHP to develop the model. The authors have applied the proposed approach to the comparative analysis of three bridges in order to select the bridge offering the best global performance in the perspective of sustainability. Isaacs et al. (Citation2008) have described a prototype visualisation tool (S-City VT) which will help stakeholders to understand and influence decisions regarding the sustainability of an urban development. The authors have mentioned that S-City VT models interactions between sustainability indicators using the ANP methodology. The authors have assigned the relative weighting of the sustainability indicators from the ANP model. The authors have mentioned that the tool can be extended by using more realistic techniques to represent traffic density indicators. The authors have expressed the need to implement crowd modelling into the tool to show how the population will move through the development. Bottero and Mondini (Citation2008) have assessed an urban transformation project in Italy, from a sustainability point of view. The authors have used the ANP method to perform the sustainability assessment of the transformation project. The authors have concluded that the problems related to energy efficiency, the aspects concerning the landmark and the new services for the inhabitants should be given highest importance. Kaya and Kahraman (Citation2011) have proposed an environmental impact assessment methodology in the context of urban industrial planning. The authors have used an integrated fuzzy AHP–ELECTRE approach to develop the proposed model. The authors have applied the proposed model to an industrial rehabilitation project prioritisation case in Istanbul. The authors have identified the most risky districts among the areas that are subject to rehabilitation. The authors have mentioned that in future research, the proposed framework can be applied to assess the impact of industrial development plans conducted for different cities or regions. They have also mentioned that similar studies can be conducted based on different fuzzy MCDM techniques such as fuzzy PROMETHEE, fuzzy VIKOR or fuzzy TOPSIS for comparative purposes. Zavadskas and Antuchevičienė (Citation2004) have analysed the problem of derelict buildings' redevelopment by means of MCDM techniques. The authors have used TOPSIS and compromise ranking method (VIKOR). The authors have performed multi-criteria analysis of abandoned buildings' redevelopment alternatives in Lithuania and have determined different priorities of sustainable redevelopment alternatives in areas of active, medium and regressing development. They have mentioned the need to apply a less sensitive method which could obviate false series of priorities due to the quality of the data. Awasthi et al. (Citation2011) presented an MCDM approach for selecting sustainability transportation systems under partial or incomplete information (uncertainty). The authors have used fuzzy TOPSIS for selecting the best alternative. The authors have selected the best sustainable transportation system based on various criteria such as operating costs, safety, security, reliability, air pollutants, noise, convenience to use, quality of service, etc.
Based on the literature review, it has been found that there exists a scope for MCDM application in a sustainable concept selection problem. In this context, in the present study, fuzzy TOPSIS has been used.
Case study
The case study has been conducted in a modular switches manufacturing organisation located in Coimbatore, a city in Tamil Nadu, India. The organisation is involved in the manufacture of rotary switches, modular switches and transformers. The organisation implements ISO 14001 environmental management system and there existed a need for the organisation to implement various sustainability concepts. In order to prioritise the sustainability concepts, this study was conducted. To select the optimal sustainability concept for the organisation, the decision-makers of the case organisation decided to use TOPSIS. The various sustainability enablers are economic (D 1), environmental (D 2) and social (D 3) sustainability. The five concepts considered are design for environment (DFE) (A 1), LCA (A 2), ECQFD (A 3), theory of inventive problem solving (TRIZ) (A 4) and life cycle impact assessment (LCIA) (A 5). The decision-makers (DMs) felt that the five chosen concepts are appropriate for the nature of the organisation. The concepts are evaluated based on 12 sustainability criteria, namely financial health (C 1), economic performance (C 2), potential financial benefits (C 3), trading opportunities (C 4), air resources (C 5), water resources (C 6), land resources (C 7), mineral and energy resources (C 8), internal human resources (C 9), external population (C 10), stakeholder participation (C 11) and macro social performance (C 12) (Vinodh Citation2011). The five concepts are being rated by three DMs, D 1, D 2, and D3, based on the 12 criteria using linguistic terms. The linguistic terms are then converted to fuzzy numbers. The decision-makers possess rich experience regarding the working culture of the organisation, and they are responsible for the implementation of sustainability concepts.
The research questions addressed are as follows:
| • | How to select the best sustainability concepts considering several sustainability criteria? | ||||
| • | How to overcome the vagueness associated with the conventional input from the DMs for the selection of the best sustainability concept? | ||||
| • | How to implement the best sustainability concept so as to advance the sustainable engineering concept? (Figure )
Figure 1 Hierarchical model used in the study.  | ||||
The linguistic variables and the corresponding fuzzy numbers are shown in Tables and .
Table 1 Linguistic variables for ratings.
Table 2 Linguistic variables for performance criteria weights.
The performance ratings for the five concepts are provided based on 12 criteria by the three decision-makers. These ratings are represented by the linguistic terms and are shown in Table .
Table 3 Performance ratings of five concepts with respect to 12 sustainability criteria.
The importance weights of each criterion are given by the three decision-makers as linguistic variables and are presented in Table .
Table 4 Importance weights of the criteria by the three decision-makers.
The aggregated fuzzy performance ratings and importance weights, x ij and W j are given as (Tsao and Chu Citation2002)
The fuzzy decision matrix and weights for each criterion are aggregated in a matrix as (Tsao and Chu Citation2002)
The aggregated fuzzy decision matrix and fuzzy weight for each criterion are presented in Table .
Table 5 Fuzzy decision matrix and fuzzy weight for each criterion.
The decision matrix is normalised in order to avoid complex operations in the decision-making process. The normalised matrix is given as (Tsao and Chu Citation2002)
The normalised decision matrix is presented in Table .
Table 6 Normalised fuzzy decision matrix.
The weighted normalised fuzzy decision matrix is given as (Tsao and Chu Citation2002)
The weighted normalised fuzzy decision matrix is given in Table .
Table 7 Weighted normalised fuzzy decision matrix.
The ideal (I +) and anti-ideal (I − ) solution for each concept is determined by using the ranking values of v ij (Tsao and Chu Citation2002).
The ideal and anti-ideal solutions for each concept is presented in Table .
Table 8 Ideal and anti-ideal solution for each concept.
Results and discussions
In this study, fuzzy TOPSIS was used as it is an outranking method; in the previous study, fuzzy AHP was used in the network category. Due to the advantage associated with the outranking method, it was desired to apply fuzzy TOPSIS. Also, the outranking methods perform better than the network-based methods. The objective of the study is to select the best sustainable concept for the case organisation from a list of five concepts. This is done by finding the distances of each concept from the ideal and anti-ideal concepts and then the closeness index is computed.
The distances of each concept A
j
from I
+ and I
− are now determined. Let and
be the distances of each concept from the ideal and anti-ideal solutions, respectively (Tsao and Chu Citation2002).
Table presents the distance of each choice from I +and I − .
Table 9 Distance of each concept from ideal and anti-ideal solutions.
The closeness coefficient , i = 1,2,…,m, is calculated as (Tsao and Chu Citation2002)
Table presents the closeness index of each choice.
Table 10 Closeness index.
The alternative A
i
is closer to the ideal point and farther from the anti-ideal point
as c
i
* approaches 1, the ranking order of all alternatives can be determined and the optimum choice can be selected according to the closeness coefficient (Tsao and Chu Citation2002).
Thus, based on the values of the closeness index presented in Table , we infer that the concept A 3 is the optimal choice. The ranking order of the different concepts as seen from Table is given as A 3>A 4>A 5>A 2>A 1. Thus, the optimal sustainability concept is A 3 (ECQFD). ECQFD is an effective approach which enables the case organisation to handle both environmental and traditional requirements in a scientific manner. ECQFD consist of four phases. ECQFD phases I and II are concerned with the identification of components that are focused on product design considering both environmental and traditional requirements. ECQFD phases III and IV enable the design engineers to examine the possibility of design improvements of components and to determine the improvement effect of design changes. ECQFD is used to identify the design options by performing trade-offs between environmental and traditional design requirements. In future, other concepts such as DFE, LCA, TRIZ and LCIA can also be implemented. DFE is a design where ‘the environment’ helps to define the direction of design decisions. In DFE, the environment is given the same status as more traditional product values. The environmental aspects in each stage of the product development process are considered in DFE, striving to achieve products that have the lowest possible environmental impact throughout their entire life cycle (Rose Citation2000). LCA is a method where the environmental impact of a product, process, services or system is assessed by taking into account every step in its life cycle. LCA is mainly used for analysing environmental impacts of products and industrial services (Parent and Lavallée Citation2011). TRIZ helps to provide means for problem solvers to access the good solutions obtained by the world's finest inventive minds. In TRIZ problem, definers and problem solvers must map their specific problems and solutions to and from the generic framework. The four main elements that make TRIZ different from other innovation and problem-solving strategies are contradictions, functionality, ideality and use of resources (Mann Citation2001). LCIA aims at translating the findings from an inventory in an impact profile that consists of 10–12 different environmental themes such as global warming, ozone depletion and acidification. A better understandable and more reliable result can be achieved based on this impact profile. The large volume of inventory information is made more understandable by the concentration of information (Saur Citation1997).
Conclusion
Sustainability enables the modern manufacturing organisations to develop environmentally friendlier products. Sustainability addresses three major dimensions, namely environment, economy and society. It involves several concepts such as DFE, LCA, ECQFD, QFD and LCIA. The selection of the best sustainable concept is a typical MCDM problem. In this study, outranking MCDM method, namely fuzzy TOPSIS, was used to select the best sustainable concept among five concepts, namely DFE, LCA, ECQFD, TRIZ and LCIA. The decision-makers' inputs have been gathered and the MCDM problem has been solved using TOPSIS approach. The best concept from the perspective of sustainability is ECQFD. The ranking order of the five concepts is A3>A4>A5>A2>A1. The selected concept design has been subjected to implementation. The result inferred from the conduct of the study is that TOPSIS is found to be an effective approach towards the selection of best sustainable concept.
Acknowledgements
The authors are thankful to Department of Science and Technology (DST), New Delhi, India, for sanctioning the fund towards the execution of project titled ‘Development of a model for ensuring sustainable product design in automotive organizations’ (Ref No.SR/S3/MERC-0102/2009). This research study forms a part of this major research project.
Related Research Data
References
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