David Opresnik
email: david.opresnik@polimi.it

Marco Seregni
email: marco.seregni@polimi.it

Marco Taisch
email: marco.taisch@polimi.it

The Cornerstone of Sustainability Strategy in Manufacturing Enterprises

Keywords: sustainability, strategy, manufacturing, sustainable manufacturing

Sustainability has already been seen to impact positively the competitive advantage of an enterprise. Nonetheless managing sustainability still too often represents a conundrum. Consequently, the aim of this article is to help managers of manufacturing enterprises to understand, from an integrative perspective, the impact of the concept of sustainability onto their enterprise, with the objective to increase their long-term success. Thus, it was first assayed, if sustainability is a strategy and what are its main characteristics. To ensure validity, we leaned on the most renowned definitions of "strategy". Secondly, an integrative framework for sustainability in manufacturing enterprises was designed, depicting the interrelations among the enterprise's core elements (strategies, tactics, operations) and also with the environment (legislature and market), while dedicating special attention the concept of "fit". The results altogether creates the cornerstone of the strategy of sustainability for manufacturing enterprises.

Introduction

According to the National Association of Manufacturers, the manufacturing sector has the highest economic multiplier effect of all sectors [START_REF]Global Agenda Council on Advanced Manufacturing[END_REF]. Thus, manufacturing plays one of the key roles not only from an economic, but also from a social perspective, as it is a crucial provider of jobs. However, due to an increasing global competition, manufacturing enterprises in mature economies are facing a challenge how to grow on the long-term, while providing high quality jobs within a much stricter legislative environment then some of their peer countries. Thus, they are forced to define new sustainable but competitive growth alternatives. Namely, a single-minded focus on economic sustainability can succeed only in the short run; though, while long-term success requires all three dimensions of sustainability -economic, society and environment [START_REF] Dyllick | Beyond the business case for corporate sustainability[END_REF], [START_REF] Gladwin | Shifting paradigms for sustainable development: Implications for management theory and research[END_REF]. Those three dimensions of sustainability are called the Triple Bottom Line (TBL) [START_REF] Elkington | Partnerships from cannibals with forks: The triple bottom line of 21stcentury business[END_REF] through which an enterprise can create more long term value and achieve a higher long term competitive advantage, while encountering fewer risks [START_REF] Dyllick | Beyond the business case for corporate sustainability[END_REF], [START_REF] Michael | Running business like a government in the new economy: lessons for organizational design and corporate governance[END_REF]- [START_REF] Valente | Theorizing Firm Adoption of Sustaincentrism[END_REF]. However, sustainability brings many challenges. Namely, managers are realizing that sustainability is becoming part of their business, but they fear the risk of failing in dealing with it [START_REF] Berns | The business of sustainability: what it means to managers now[END_REF].

They have trouble understanding the incorporation of sustainability and the implications of their actions on long-term success [START_REF] Epstein | Making the business case for sustainability[END_REF]. Thus the difficulty is no longer whether to implement sustainability, but how [START_REF] Epstein | Sustainability in action: Identifying and measuring the key performance drivers[END_REF]. Hence, as sustainability in enterprises still represents a conundrum, the aim of this article is to help managers of manufacturing enterprises understand, from an integrative perspective, the integration of sustainability, in order to enable them to exploit it as a new basis for long-term competitive advantage. Consequently, the following research questions are set: a) is sustainability in a manufacturing enterprise really a strategy and if it is so, which are its main characteristics, b) in which elements of the enterprise (strategic, tactical, operational) is sustainability applicable and what are the interrelations among them, c) what is the impact of the environment (legislature and market)? The results will be twofold: first depicting the main characteristics of sustainability as a strategy and secondly, through an integrative sustainability framework, identifying and assaying the main previously mentioned interrelations. Those two sets of results together represents the cornerstone of sustainability in manufacturing enterprises.

The value of this work for managers of manufacturing enterprises lies in helping them optimize their market position by using sustainability and to optimize its management. As for theory, it offers the first integrative framework for sustainability as a strategy for a manufacturing enterprise, taking into account the concept of fit. The article goes as following. After the literature review, the main definitions of the term "strategy" are assayed and applied on the concept of sustainability. In the next step, the main results are synthesized into an integrative framework.

Literature review

Following the concept of sustainability science [START_REF] Clark | Sustainability science: the emerging research program[END_REF], this article is per se transdisciplinary, gathering the main pillars steaming from manufacturing, sustainability and strategy. Sustainable development goes back to Agenda 21 [START_REF] Sitarz | Agenda 21: The earth summit strategy to save our planet[END_REF], an important policy document for sustainable development that was adopted at the Rio World Summit in 1992. Sustainability has many definitions, though the most famous is probably from Brundtland's report [START_REF] Brundtland | World commission on environment and development[END_REF]: "… the ability to meet the needs of the present without compromising the ability of future generations to meet their own needs". Though there are many other definitions of suitability, the framework of the TBL [START_REF] Elkington | Partnerships from cannibals with forks: The triple bottom line of 21stcentury business[END_REF] is chosen to work with in this article, as it is depicting the economic, social and environmental aspect of sustainability. Regardless of its high-level principal, sustainability can still be monitored, assessed and reported. An organization's performance in the wider context of sustainability is presented via reporting, using e.g. GRIG4 reporting guidelines. Another possibility to identify in more detail relevant elements of sustainability is to use a priority matrix [START_REF] Bordt | OECD Sustainable Manufacturing Toolkit[END_REF]. Nonetheless, sustainability comes down to subjective rating, as the criteria and their indicators are mostly chosen and calculated based on opinion of experts, although much more exact techniques are also employed in the context of environmental sustainability like the Life Cycle Assessment technique [START_REF] Ibáñez-Forés | A holistic review of applied methodologies for assessing and selecting the optimal technological alternative from a sustainability perspective[END_REF].

Sustainability on the enterprise level is most often referred to as corporate sustainability. According to the Dow Jones Sustainability Index -it is a business approach that creates long-term shareholder value [START_REF] Epstein | Making the business case for sustainability[END_REF]. Interestingly sustainability within an enterprise seems to enable an early-mover advantage in international markets [START_REF] Porter | Green and competitive: ending the stalemate[END_REF] or should even go as far as underpinning the current business models that are based on the idea to sell as much products as possible [START_REF] Garetti | Sustainable manufacturing: trends and research challenges[END_REF]. Sustainability has also been linked with the strategic management tool the Balanced Scored Board [START_REF] Kaplan | Linking the balanced scorecard to strategy[END_REF], resulting in a Sustainability Balanced Scorecard encompassing a perspective of the three pillars of sustainability [START_REF] Figge | The Sustainability Balanced Scorecard -linking sustainability management to business strategy[END_REF]. Sustainability, the social part, has been also scrutinized in relation to manufacturing [START_REF] Fantini | Social Sustainability: Perspectives on the Role of Manufacturing[END_REF]. Regardless of its positive impact, sustainability is also criticized. It is argued that the concept is useless because it cannot be adequately defined [START_REF] Costanza | Defining and predicting sustainability[END_REF] or that the term "sustainable development" is oxymoronic; how can something develop if it is to remain the same (i.e. "sustainable")? [START_REF] White | Sustainability: I know it when I see it[END_REF]. As identified, sustainability represents a high-level guidance that is certainly useful to some extent, however do not meet the rigid requirements to fully operationalize sustainable development in all the levels of the enterprise integrally, while taking into account the specificities of a manufacturing enterprise.

Methodology

This article conceptualizes the strategy of sustainability within a manufacturing enterprise. The dependent variable is long-term competitive advantage of a manufacturing enterprise. The independent variable is the strategy of sustainability. In this context, it is first delved if sustainability can even be considered as a strategy, by benchmarking it against the most renowned definitions of this term. Basing the conceptualization of the strategy of sustainability on rigid criteria in intermediate steps, it allow us to avoid the "problem of demarcation"; thus the article draws on Karl Popper's philosophy and onto its "falsificationism", claiming that "a hypothesis is scientific if and only if it has the potential to be refuted by some possible observation" [START_REF] Godfrey-Smith | An introduction to the philosophy of science: Theory and reality[END_REF]. In the spirit of this philosophy, we included strict criteria enabling us to critically refute the propositions made in this article.

Model development

In order to identify the cornerstones of the strategy of sustainability for a manufacturing enterprise, the following conceptualization steps are followed. First, in order to position with validity sustainability into a manufacturing enterprise, it has to be reviewed if it can be treated as a strategy and what are its main characteristics. To scrutinize this, the main definitions of strategy are assayed, from which its most relevant characteristics are then derived, representing the next step. Finally, based on the results, an integrative framework depicting all the main interrelations relevant for the strategy of sustainability is designed.

Sustainability has already in some cases been recognized as a strategy [START_REF] Epstein | Using a Balanced Scorecard to Implement Sustainability[END_REF], [START_REF] Unruh | The Sweet Spot of Sustainability Strategy[END_REF], in some cases as a perspective of a strategy [START_REF] Figge | The Sustainability Balanced Scorecard -linking sustainability management to business strategy[END_REF].The need for its management has been also widely acknowledged at different levels of the enterprise [START_REF] Asif | Including sustainability in business excellence models[END_REF], [START_REF] Corbett | Sustainable operations management: A typological approach[END_REF]. The first definition of strategy is presented according to Porter [START_REF] Porter | What is strategy?[END_REF], stating that strategy is the creation of a unique and valuable position, the way a firm chooses activities that differ from those of the competitors. If sustainability is able to create such position and choose differently its activities, it can be seen as a strategy. In addition, it would mean that it does not have only to position itself with a unique and/or valuable position, but it also has to relate this position to some operations within the enterprise. Namely, Porter [START_REF] Porter | The competitive advantage of corporate philanthropy[END_REF] defines operational effectiveness and the choice of strategic positioning essential for a performance on the longer term. According to the second definition from Quinn [START_REF] Quinn | Strategies for change: logical incrementalism[END_REF], strategy is: "The pattern or plan that integrates an organization's major goals, policies, and action sequences into a cohesive whole." This would indicate sustainability to be a viable strategy that has to encompass the enterprise as a cohesive whole, thus indicating the urge for an internal fit. The concept of fit has been viewed as an internal consistency among key strategic decisions or the alignment between strategic choices and critical contingencies with the environment (external) [START_REF] Ensign | The concept of fit in organizational research[END_REF], being essential for long-term success [START_REF] Govindarajan | Implementing competitive strategies at the business unit level: implications of matching managers to strategies[END_REF]. The third definition of strategy defines it as the pattern of decisions that determines and reveals its objectives and produces the principal policies and plans for achieving those goals. It also defines the range of business the company is to pursue, the kind of economic and human organization it intends to be, and the nature of the contributions to various stakeholders [START_REF] Foss | Resources, Firms, and Strategies: A Reader in the Resource-based Perspective[END_REF]. Such patterns and principal policies can also represent the integration of sustainability into the enterprise. According to this definition of strategy, priorities from the economic and human perspectives have to be assumed, as also to which stakeholders and to what extent the strategy should take into account those elements. Finally, according to Barney [START_REF] Barney | Gaining and sustaining competitive advantage[END_REF] "a good strategy … neutralizes threats and exploits opportunities while capitalizing on strengths and avoiding or fixing weaknesses." This would indicate that sustainability within a manufacturing enterprise should be applied selectively, depending at least of the environment (legislative and market) and the relative position of the manufacturing enterprise itself. Hence, this means that sustainability is a viable strategy only when it presents itself as an opportunity to be exploited or as a threat that can be converted into an opportunity. However each business strategy is unique [START_REF] Rumelt | Evaluating business strategy[END_REF], therefore contingent upon many factors.

The Cornerstones of the Strategy of Sustainability

In the previous section, the main characteristics of a strategy in general were presented. In this subsection, four main characteristics are chosen, from which the main characteristics of sustainability strategy are derived. Afterwards the integrative framework for sustainability is depicted. Those two results constitute the cornerstone of sustainability for a manufacturing enterprise. The four main characteristics are the following (note: after each characteristic that is listed, it is then explained how it relates to sustainability).

First strategic characteristic. A strategy enables the manufacturing enterprise to position itself with a unique and/or valuable proposition [START_REF] Porter | What is strategy?[END_REF], [START_REF] Mintzberg | The Strategy Concept 1: Five P's for Strategy[END_REF]. Sustainability can enable to change the strategic positioning of an enterprise (e.g. accessing a new customer segment). This positioning depends on the internal as well as on the external context, which is the market (i.e. industry, competition, trends etc.), and the legislative environment that is defining among others incentives for sustainability in manufacturing. Therefore, the positioning of a manufacturing enterprise based on the strategy of sustainability is contingent upon external context, which are the market and the legislative environment (see Fig. 1).

Second strategic characteristic. A strategy neutralizes threats and exploits opportunities while capitalizing on strengths and avoiding or fixing weaknesses [START_REF] Barney | Gaining and sustaining competitive advantage[END_REF]. Hence, the strategy of sustainability per se can represent itself as an opportunity or as a threat, thus how sustainability is perceived by an enterprise is contingent upon multiple factors. In a supportive environment for sustainability, moreover a supportive legislative (e.g. incentives for environment and social inclusiveness) and a supportive business environment (e.g. consumers are willing to pay a premium for sustainability related product-services), sustainability can represent a threat or an opportunity. Instances of both presented. Firstly, it represents a threat to the focal enterprise, if it cannot take advantage of the opportunities arising from the environment, while its competitors can. For instance, the focal enterprise has to close down its production plant due to a CO2 emission excess or cannot take advantage of development funds related to sustainability activities or cannot satisfy the new consumer trends, while its competitor can. However, secondly, if the focal enterprise has the internal capabilities to deploy the strategy of sustainability throughout its value chain and thus take advantage of the opportunities arising from such environment, then sustainability presents itself as an opportunity. It is even greater, if its competitors, on the other hand, are not able to take advantage of them. This would indicate that the focal enterprise is deploying a new basis for their long-term competitive advantage. Thirdly, if the focal enterprise intends to take advantage of the opportunities arising from sustainability, but it has assessed poorly its own internal capabilities for deploying such a complex strategy, than this strategy is seen as a threat. The application of such strategy would then impede the growth of its long-term competitive advantage. This case can be classified as a threat and not a weakness, because the sustainability strategy arise from the environment and not from the enterprise, however, it is also true that is transforming itself into a weakness after its integration.

Third strategic characteristic. After positioning itself in relation to sustainability, the manufacturing enterprise must choose activities that differ from the competitors and relate them to the newly chosen position [START_REF] Porter | What is strategy?[END_REF]. Based on the strategy of sustainability, the enterprise must define its priorities in sustainability. They have to arise from the strategy and reflect onto the operations, for which the adequate manufacturing tactics have to be chosen.

Forth strategic characteristic. In order to be able to align the strategy with its tactics and operations on one hand and to align them with the environment afterwards, managers must encompass the enterprise as a cohesive whole, while indicating the urge for an internal fit [START_REF] Quinn | Strategies for change: logical incrementalism[END_REF]. Thus, two fits must exist. One that aligns the strategy with the tactical and operational level and the second that aligns the internal strategy with the environment. The former fit is essential, because according to a strategy of sustainability, specific tactics and operations have to be chosen and well aligned. It means, for example, that if at the operational level a production line is optimized in terms of energy efficiency, also sustainability related improvements should be undertaken at the tactical level (e.g. product-services for sustainable consumption) as also should be aligned with the strategy. Only at the point when the two fits exist (internal and with the environment), a manufacturing enterprise can be seen as an optimized sustainable system. Otherwise, inefficiencies and opportunity costs arise, that in turn does not increase maximally its long-term competitive advantage. As for the second fit, the one between the enterprise and the environment is also crucial. Namely, if the legislative and business The integrative model for sustainability of manufacturing is depicted on Error! Reference source not found.. One component is the environment, constituted by the legislation and market, while the second segment is the enterprise. It has three main subsegments, commencing with the strategy, going down to tactics and operations that are critical for manufacturing, while all are supported and performed by managerial processes. Each element is made of three layers, representing the TBL. Furthermore, the two fits can be seen with the two darker arrows, one among internal elements in the enterprise (strategy, tactics, operations) and the second between the enterprise and the environment. In the next research steps, it should be identified what exactly constitutes a sustainability strategy, to go another step closer to operationalize sustainability in an enterprise.

Conclusion

Sustainability through the perspective of a manager in a manufacturing enterprise was delved. In order to do so, it was first assayed if sustainability was a viable strategy for manufacturers, by leaning on the most renowned definition of the term "strategy". After confirmation, the key characteristics of the strategy of sustainability were derived. During the analysis, it was identified that sustainability is omnipresent in the enterprise as well as in the environment. Hence, managers must manage the strategy of sustainability integrally, taking into account all of its components within the enterprise (strategy, tactics, operations and management), the fit among them, as also the fit between the enterprise and its environment (legislature and market).

Managing those complex and dynamic interrelations, while leaning on the key characteristics of the strategy of sustainability formed the cornerstone of sustainability strategy in manufacturing enterprise. Nonetheless, sustainability strategy is not a standalone strategy, but represents an additional basis for increasing the long-term competitive ad-vantage. As it quite complex to manage, it is hence also very hard to imitate it, consequently being able to sustain such competitive advantage for a longer time, making the strategy of sustainability a sustainable one for a manufacturing enterprise.

Fig. 1 .

 1 Fig. 1.The Strategy of Sustainability -fit and positioningenvironments are not supportive towards the application of sustainability in manufacturing, which is the case for countries where industrialization has just begun or is still undergoing, then the strategy of sustainability for an enterprise in such an environment has no meaning. It can even become a threat, if the focal enterprise invests considerable amounts of resources into implementing sustainability, while no new business opportunities open up due to this investment.The integrative model for sustainability of manufacturing is depicted on Error! Reference source not found.. One component is the environment, constituted by the legislation and market, while the second segment is the enterprise. It has three main subsegments, commencing with the strategy, going down to tactics and operations that are critical for manufacturing, while all are supported and performed by managerial processes. Each element is made of three layers, representing the TBL. Furthermore, the two fits can be seen with the two darker arrows, one among internal elements in the enterprise (strategy, tactics, operations) and the second between the enterprise and the environment. In the next research steps, it should be identified what exactly constitutes a sustainability strategy, to go another step closer to operationalize sustainability in an enterprise.

Acknowledgement. This work has been partly funded by the European Commission through the FoF-ICT Project MSEE: Manufacturing SErvice Ecosystem (No. 284860). The authors wish to acknowledge the European Commission.


Alice Bush
email: alice.bush@polimi.it

Claudio Palasciano
email: claudio.palasciano@polimi.it

Alberto Portioli Staudacher

Marco Taisch
email: marco.taisch@polimi.it

Stefano Vitali
email: stefano.vitali@morsetec.it

Investigating Lean Methodology for Energy Efficient Manufacturing

Keywords: energy efficiency, sustainable manufacturing, continuous improvement, CIP, lean manufacturing, green manufacturing, energy value stream analysis, EVSA, energy value stream mapping, EVSM

D u e t o the growing globalization and the increasing interest in environmental concerns, together with t h e changing legal and regulations landscape, manufacturers need to change their approach to competition, enhancing their knowledge of the manufacturing systems and of the network of interconnections among physical flows and management and control information flows, while developing systemic methodologies that enable waste reduction of manufacturing resources usage (such as energy). Furthermore, companies are increasingly involved in managing the environment as an opportunity for competitive advantage, which establishes the need to highlight the relationships between environmental impact of their processes and company strategy and objectives. This paper presents a proposal for a lean methodology, called T r a n s f o r m a t i o n D i s t r i b u t i o n a n d U t i l i z a t i o n ( n a m e l y , T.D.U.) methodology, which allows future factories to identify V a l u e A d d e d e n e r g y u s a g e , p a v i n g t h e w a y t o activities that can reduce t h e r e l a t e d inefficiencies a n d w a s t e s . The T.D.U. methodology has been tested in real company, MorseTEC Europe, a supplier of systems for European car manufacturers.

Introduction

Due to the growing globalization and the increasing interest in environmental concerns, together with the changing legal and regulations landscape, manufacturers need to change their approach to competition, enhancing their knowledge of the manufacturing system and of the network of interconnections among physical flows and management and control information flows, while developing systemic methodologies that enable waste reduction of manufacturing resources usage (such as energy). We want to propose a new lean approach, the new T r a n s f o r m a t i o n D i s t r i b u t i o n a n d U t i l i z a t i o n ( T.D.U.) methodology with the objective to reduce wasted energy within manufacturing processes and in particular presenting and testing it in a real case study in MorseTEC Europe, a supplier of systems for many European car manufacturers.

Related Work

The role of energy management in manufacturing is vital and has greatly found application in industry, see for instance [START_REF] Abdelaziz | A review on energy saving strategies in industrial sector[END_REF]. Anyway, there is a wide implementation gap between practice and theory, especially concerning tools for measurement, assessment, control and improvement of energy efficiency in manufacturing companies [START_REF] Bunse | Integrating energy efficiency performance in production management -gap analysis between industrial needs nad scientific literature[END_REF]. Many authors have investigated the aspects concerning the need to enhance manufacturing modeling frameworks and tools to enable energy and resource efficient manufacturing. For instance ISA 95 [START_REF]ISA-95 International standard for the integration of enterprise and control systems[END_REF] standard includes process and information flow models enabling representation of additional elements beyond the usual material flows, such as energy consumption, carbon dioxide, emissions, wastes. Various works, such as [START_REF] Choi | Manufacturing process modelling for environmental impact assessment[END_REF], [START_REF] Shao | Interoperability for simulation of sustainable manufacturing[END_REF], [START_REF] Thiede | Process chain simulation to foster energy efficiency in manufacturing[END_REF], [START_REF] Fysikopoulos | On a generalized approach to manufacturing energy efficiency[END_REF] and [START_REF] Duflou | Towards Energy and Resource Efficient Manufacturing: A processes and systems approach[END_REF] extend ISA 95 reasoning by proposing the development of manufacturing modeling frameworks able to capture the complex network of dynamic interactions among the physical flows in the factory, input flows (materials and parts , energy, human resources, etc. ) and output flows (products, scrap and solid wastes, emissions, heat, noise etc.), at the different level of the factory, from machine to lines, up to plant/sites. Other authors have studied modeling concept and methods starting from the observation that machines and other production systems can be in different operating modes (such as "on", "stand by", "processing", etc.) to which correspond different energy consumption profiles. These studies have leveraged on the operating modes concept in many ways, such as supporting manufacturing planning [START_REF] Weinert | Methodology for planning and operating energy-efficient production systems[END_REF], identifying energy saving machine control policies [START_REF] Prabhu | Modeling green factory physics -An analytical approach[END_REF], energy monitoring [START_REF] Vijayaraghavan | Automated energy monitoring of machine tools[END_REF]. All these contributions show how energy efficiency can depend on both technical design choices and organizational decisions, such as production planning and control and machine control. Anyway, in literature there is no clear method to extend this approach from the machine/component level to the whole factory. Furthermore, some authors report that enterprises are increasingly involved in managing the environment as an opportunity for competitive advantage, that requires highlighting the relationships between environmental impact of their processes and company strategy and objectives [START_REF] Garetti | Sustainable manufacturing: trends and research challenges[END_REF]. Finally we highlight the most interesting related works, which confirm the above mentioned need of energy and resource efficient analysis methods and tools. Drechsel et al. [START_REF] Drechsel | A New Approach to Integrate Value Stream Analysis into a Continuous Energy Efficiency Improvement Process[END_REF] draw the first steps towards the development of an Energy Value Stream Analysis (EVSA), a new approach extending Value Stream Mapping (VSM), a technique for lean manufacturing, developed to support the identification of productive and nonproductive usage of manufacturing resources, for a holistic analysis of energy productivity. The contribution describes how to integrate the EVSA in a Continuous Improvement Process (CIP) in which energy saving potentials are identified by a team involving managers/experts of the various production process steps under analysis. Plehn et al. [START_REF] Plehn | From Strategic Goals to focused Eco-efficiency Improvement in Production -Bridging the gap using Environmental Value Stream Mapping[END_REF] explore the basic structure of a proposed Environmental Value Stream Mapping (EVSM) as an interface between a multi-criteria performance measurement system and the environmental and economic process flows of a manufacturing system. The main point of the proposed EVSM is the identification of usage of resource flows in different states in time (processing, set-up, stand-by etc.). Fantini et al. [START_REF] Fantini | Towards Environmental Conscious Manufacturing[END_REF] propose novel modeling features for each element in the manufacturing systems, features capable to describe their behaviour in terms of resource consumption and release of produced products and parts as well as waste and emissions. The authors propose a systemic approach to manufacturing modeling under a holistic perspective, which includes all elements in a factory such as production systems, technical building services (TBS) and building shell and their network of interconnections with factory management and control levels. To address both manufacturing and environmental performance, the specification of manufacturing elements requires in fact the description of the whole transformation process enacted by the production systems and the systems supplying them and the dynamics of the material and energy flows in input and of the parts and waste in output. To summarize, academia and industry experts recognize the widespread need for energy efficiency modeling frameworks and methodologies, able to support collaborative teams in their continuous improvement analysis and programs with the integration of proper KPIs and performance indicators systems.

3

Approach: Lean Methodology for Energy Efficient Manufacturing

Identification of Value and Non Value Added Energy

It is estimated that in most of the companies, 40-70% of total activities are carried out without adding value to the customer. These activities are considered as waste and competitive advantage can be achieved through these waste reduction [START_REF] Ohno | Toyota Production System: beyond large-scale production[END_REF], [START_REF] Womack | Beyond Toyota: How to Root Waste and Pursue Perfection[END_REF]. The Lean Production is Toyota Production System approach that that focuses on waste reduction to improve operations' performances, and gave quite interesting results in many implementations (e.g. Womack and Jones [START_REF] Womack | Lean Thinking[END_REF]; [START_REF] Soahl | Developing a lean production organization: an Australian case study[END_REF]; Lean Enterprise Institute www.lean.org) and therefore it is possible to use this approach also with the aim of identifying the energy wastes and remove them. One of the most important concepts of the Lean Approach is the distinction between Value Added Activities (VAA) and Non Value Added Activities (NVAA). Especially, VAA are all those activities required for the customers, for which they are willing to pay in achieving the final product. The NVAA activities are those not strictly required such as material handling or inventory holding.

The concept of value added can be applied also in energy management field. According to Frazier [START_REF] Scott | Bandwidth analysis, lean methods and decision science to select energy management projects in manufacturing[END_REF] the Value Added Energy (V.A.E.)is the energy used for all the activities that create value for costumers, and the Non Value Added Energy (N.V.A.E.), the energy consumption related to the Non Value Added Activities.

V.A.E. = T.E. N.V.A.E = Actual Energy -T.E.

where:

• Theoretical energy (T.E.): the minimum energy required to produce the desired transformation; • Actual Energy: the energy really used for the desired transformation. [START_REF] Seow | A framework for modelling energy consumption within manufacturing systems[END_REF] propose a different point of view, in which they identify three energy typologies:

Seow and Rahimifard

• Theoretical Energy (T.E.): the minimum energy required to carry out the production process. • Auxiliary Energy (A.E.): the Energy required by the supporting activities and auxiliary equipment for the process. A.E. also includes non-productive modules such as machine tool change, startup, stand by and cleaning. • Indirect Energy (I.E.): the energy consumed to ensure the correct workplace conditions for the productive processes such as lighting, heating and ventilation.

Integrating and extending these three different point of views and the aforementioned holistic perspective [START_REF] Vijayaraghavan | Automated energy monitoring of machine tools[END_REF] we propose here as a starting point an high level framework that enables a thorough and systematic assessment of performance of manufacturing systems along multiple dimensions in terms of production performance, economic performance and environ mental impact, suited in particular to identify energy flows, that may happen in production systems and in the services systems (TBS for instance) as well. Focusing on the physical flows in the system, in Figure 1 we show how Total Resources (TR), such as raw materials, energy, human resources, consumables, etc., can be used:

• partially -the Valuable Resources VR -to produce non-defective final products (valuable output VO); • partially -namely, the non-valuable resources NVR -can be wasted d u r i n g non-valuable adding activities or while producing defective products,therefore becoming "NonValuable" Output NVO. These w asted resources can be considered "Unwanted" Output (UO), toge ther with all environmental impacts (EI).

The main idea of this paper is finding valuable and non-valuable usage of resources along their whole physical flows, in particular concerning how to identify Value Added Energy, instead that along the traditional transformation flow, for instance from raw materials to product/part produced. Based on the aforementioned three different point of views proposed by literature, Theoretical Energy is the proxy for the Value Added Energy, but under the holistic perspective we can see that this is not enough, as it does not include all energy flows that allow a quality compliant production. We want to introduce in this paper a new concept of VAE, considering the concept of value related to what the customer is willing to pay for the final product compliant with the desired quality level.

Therefore we propose to classify energy into three different typologies:

• Direct Energy (D.E.): VAE for the final clients, that is the theoretical energy used for all the activities that create value for costumers. • Accessory Energy (A.E): VAE for the internal client, that is the theoretical energy used t o allow the factory operators to perform their work in comfortable conditions, (for instance, co mfort temperature and lighting level) . • Actual Energy: the energy actually used for the desired transformation.

Based on this classification we can compute the VAE is:

Value Added Energy = Direct Energy (DE) + Accessory Energy (A.E.)

The difference between Actual Energy and VAE is waste and can be considered a potential opportunity for improvement. The table below (Table 1) presents some improvement areas for energy efficiency, by translating the 7 wastes, considered in Lean Philosophy, in energy wastes. This methodology is simple enough to be used in SMEs, as it is based on a checklist approach that drives the user in identifying which kinds of utilities (production systems, TBS etc.) are involved, in particular focusing on each different phase.

Once defined all the utilities involved in each phase, for each of them a checklist is provided, that encloses all the energy saving activities that can be implemented in that specific utility. This checklist was obtained by the analysis of scientific publications, documentations prepared by the E.N.E.A. (Italian national agency of new technologies, energy efficiency and sustainable development), reports published by the U.S. Environmental Protection Agency, real case studies of success ful applications of energy efficiency activities and direct evidence of meetings and conferences. In this way users of the T.D.U. m e t h o d o l o g y have in few pages the summary of the state of art of the industrial energy efficiency and can identify in a few minutes which activities can be implemented for improving the energy efficiency of their processes.

The energy flow is designed as follow: This methodology has been applied and tested with a great success in MorseTEC Europe, the European division of BorgWarner Group. This activity consists in recovering the heat generated during the compression of the air. This energy saving solution is a relatively simple and in recent years has been implemented in different production realities. MorseTEC has three big compressors and decided to implement this solution on its 135 kW compressor. With this energy available and an opportune heat exchanger installed in this machine it is possible to heat enough water for HVAC system for heating 1000 m 2 . MorseTEC now uses the recovered power for heating his administrative offices, with have a total surface area of 900 m 2 and an average height of 2.8 m. The excess power is used to produce hot water for showers of the workers restrooms.

Application Case Study

For implementing this solution it has been made a feasibility study for understanding the potentiality of this activity and have spent about 40.000 € for the heat recovery equipment made off by an heat exchanger, insulate piping necessary to bring the hot water to the H.V.A.C. system and 2 insulated tanks for storing the hot water.

Most part of this investment has been financed by other energy saving activities: it has been calculated that the economic saving generated by this solution amounts to 18.000 €/year. MorseTEC buys externally the heating water service and this saving represents the thermal energy consumption that the company is able to recover from its compressor . The expected payback time of this investment is equal to 2 years and 3 months.

Conclusions

As we stated before, putting effort in improving energy efficiency process is be-coming more and more relevant for Companies, to reach a higher competition level. Lean Approach concept of waste management is not only related to products and time, but also can be translated to energy. The approach proposed for improving energy efficiency in manufacturing takes into account many contributions from literature, however its innovation is on how to identify Value Added Energy, based on the classification of energy in three different categories. Then we proposed a methodology, called T.D.U. methodology with the main objective to identify three main different phases in which applying a checklist for each facility used in every phase. The checklist is formed by several standard questions, and answering to that questions leads to implement specific activities for removing part of NVAE.

Fig. 1 .

 1 Fig. 1. Valuable, Non Valuable, Un-wanted Flows

  Distribution and Utilization ( T . D . U . ) methodology w e propose is based on identification of Value Added Energy flows in three phases: • Transformation phase: the energy sources are transformed, if needed, in the energy used d i r e c t l y in the production processes. • Distribution phase: the energy and related transformed vectors (such as compressed air) are brought where the transformation takes place. • Utilization phase: the energy is finally consumed on the shop floor in the production processes (compressed air and thermal energy; electrical driving force and fuel etc.) and on the work place (lighting and heating ventilation and air conditioning systems).

Fig. 2 .

 2 Fig. 2. Energy flow within the 3 main phases.

  Europe has represented for over 15 years the expression of the European division of BorgWarner Group. Located in Arcore, 20 km northeast of Milan, MorseTEC Europe is a partner of absolute importance as a supplier of systems for most European car manufacturers (Ford, Audi, General Motors, Fiat, Volkswagen, Jaguar and PSA) by offering exclusive service, competence and experience in the development and production of distribution systems and transmission chain. In this section there will be presented some activities implemented in the plant of Arcore of the BorgWarner MorseTEC Europe after the application of the T.D.U. methodology. Specifically are reported two examples of the activities implemented in the Morse-TEC plant: heat recovery from compressors and energy consumption reduction by equipping compressor with an inverter. Energy Saving Activity #1: heat recovery from compressors • T.D.U. Phase: Transformation_compressed air • Checklist question: Is the heat emitted by your compressors recovered? • Answer: No • Solution: Purchase of Heat exchanger for compressors • Type of activity: Opportunity • Status: Completed

Energy Saving Activity # 6 :

 6 Compressor Equipped with an Inverter • T.D.U. phase: Transformation_compressed air • Check list question: Is your compressor equipped with an inverter? • Answer: No • Solution: Purchase of a compressor with an Inverter • Type of activity: Opportunity • Identified NVA energy: 98.500 kWh / year • Status : Completed

Table 1 .

 1 Energy Wastes and Improvement Areas

	7 Wastes	Energy Wasted connected with production
	Transport	Energy used for transport inside / out the warehouse, plant and
		factory
	Inventory	Heating, cooling and lighting inventory storage and warehouse
	Motion	Heating, cooling and lighting inventory storage and warehouse
	Waiting	Heating, cooling, and lighting during production downtime
	Overproduction	Energy consumed in operating equipment to make un-necessary
		products
	Over-processing	Energy to unnecessary processing
	Defects	Energy used to process defective products

Table 1

 1 MorseTec Europe (European level manufacturer system provider) applied the T.D.U. methodology and we briefly reported the results of the activities done: in the table below costs and benefits obtained by the two activities are summarized : MorseTEC case study: cost benefit analysis By applying this easy methodology is possible to reach high economic and environmental results. The next step of this work is to better and deeper relate economical performances to environmental ones.

	Activity	T.D.U. Phase	Yearly Saving €/y	Status
	Heat Recover from	T	18.000	100%
	Compressor
	Compressor with Inverter	T	13.500	100%

Acknowledgments

The research work has been developed with the helpful and very appreciated availability of MorseTEC Europe, in particular thanks to Ing. Vitali.


Golboo Pourabdollahian
email: golboo.pourabdollahian@itia.cnr.it

Frank Steiner
email: steiner@tim.rwth-aachen.de

Environmental and social impacts of Mass Customization: An analysis of Beginning-of-Life phases

Keywords: Mass Customization (MC), Sustainability, Beginning of Life (BOL)

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

From its early introduction as a strategy, Mass Customization (MC) has significantly changed the market offer and value proposition for customers. The concept of Mass Customization emerged to deal with high levels of heterogeneity of the customers' needs [START_REF] Davis | Future Perfect. Reading[END_REF]. In the other words, Mass Customization can be seen as a hybrid competitive strategy attempting to provide customers with individualized products in a costefficient manner [START_REF] Piller | Mass Customization: ein wettbewerbsstrategisches Konzept im Informationszeitalter[END_REF]. Accordingly MC benefits the firm through profit generation thanks to the premium price. Mass Customization can be considered as an economically viable strategy since it create revenues and thus profit through turning heterogeneities of customers' needs to an opportunity to create value [START_REF] Piller | Mass Customization as an Enabler of Network Resilience[END_REF] while the cost level can be kept in a level comparable to mass produced products thanks to implementation of flexible manufacturing processes and suitable customer interaction tools.

Although evaluation of MC from an economic point of view is crucial for success of a MC firm but it is not sufficient considering other challenges that the global community face today. In this regard sustainability is considered as one of the main concerns of manufacturing companies operating in different sectors and applying different strategies. Accordingly, MC enterprises need to take steps toward being more sustainable through development of a "Win-Win-Win" strategy which is sustainable not only from economic point of view but also from social and environmental perspectives [START_REF] Elkington | Towards the Sustainable Corporation: Win-Win-Win Business Strategies for Sustainable Development[END_REF].

Nevertheless, the existing body of literature concerning MC and sustainability is extremely narrow and non-mature. There are very few studies, mainly conceptual, investigating the role of MC for environmental and social sustainability [START_REF] Pollard | Strategies For Mass Customization[END_REF][START_REF] Kleer | Mass Customization: Bridging Customer Integration and Sustainability?[END_REF][START_REF] Boër | Mass customization and sustainability: an assessment framework and industrial implementation[END_REF]. The existing gap in this regard opens up interesting research streams that can be studied to support companies in implementing MC in a more sustainable manner. Accordingly, this paper aims at investigating and identifying of potential impact factors of Mass Customization on environmental and social sustainability following a Product Lifecycle management (PLM) approach. The paper is specifically focused on potential environmental and social impacts of MC during the three main phases of beginning of life of a product life cycle namely design, manufacturing and distribution.

Beginning of Life within the product lifecycle approach

The main objective of Product Lifecycle Management (PLM) is to all the activities and processes along the whole product lifecycle phases which consists of three phases: Beginning of Life (BOL) concerning design, manufacturing, and distribution; Middle of Life (MOL) concerning usage and maintenance; and End of Life (EOL) concerning waste management strategies [START_REF] Matsokis | An ontology-based approach for Product Lifecycle Management[END_REF]. Within the product lifecycle, the BOL phase is considered as a critical phase due to its future impacts on the two other phases of MOL and EOL. The decisions which are made during the beginning of life (e.g. design phase) affect significantly on both MOL and EOL of a product. On one hand the final peformance of the product during its use phase is extremely dependent on its design [START_REF] Maropoulos | Design verification and validation in product lifecycle[END_REF], while on the other hand the proper waste management strategy depends on structure of the product the way it is manufactured.

Considering the importance of BOL, in this paper we invetigate the potential influences of MC on environmental and social sustainability during the beginning of life. In particular the impact factors are identified within the three phases of design, manufacturing and distribution. It should be noticed that the impact factors include both positive and negative ones considering that while some aspects of MC can be beneficial for sustainability, there are some other aspects which might affect negatively the environmental and social performance.

Impact Factors in the Design Phase

In the context of Mass Customization, the approach to product design differs rather strongly from the design of mass produced goods: the strategy of MC aims at integrating the customer throughout all phases of the PLC and thus includes a strong firmcustomer-collaboration during the design phase. This process of co-designing products enables the customers to articulate their individual needs and specifications for the respective product [START_REF] Piller | From mass customization to collaborative co-design[END_REF]. The involvement of the customer in the design phase potentially enhances social and environmental aspects of sustainability: from a social perspective, this early integration of customers may enable a better consideration of the functional needs of specific interest groups such as elderly users or disabled peo-ple, etc. From an environmental perspective, the collaboration with customers in the design phase bears two major impact factors: firstly, being part of the product configuration process provides customers with a learning opportunity concerning the environmental impacts of their feature selection and thus increases the customer awareness of environmental sustainability [START_REF] Badurdeen | Sustainable value co-creation through mass customisation: a framework[END_REF]. Consequently, providing customers with enough information on the environmental impact of certain product attributes during the co-design process can help the users to understand the sustainability impact of their individual choices and thus ultimately supports the design of more eco-friendly products. Secondly, the integration of customers in the design phase, protects manufacturers from implementing an excessive feature load in their products: The codesign process helps to select product attributes, which are strongly aligned with the specific customer needs in a respective market. Subsequently, co-designing with customers helps MC companies to manufacture only such products that are needed and requested by the customers and thereby avoids wasting resources for the integration of unnecessary product features [START_REF] Badurdeen | Sustainable value co-creation through mass customisation: a framework[END_REF].

Beside the co-design process itself, the aspect of modularity has to be considered in the context of the product design phase. MC products are usually characterized by the use of modular product architectures, as modularity serves as one of the main operational enablers of Mass Customization. A modular architecture enables manufacturers to produce a large number of varieties by using different combinations of product modules. That way, modularity allows manufacturers to benefit from economies of scale and reductions in production lead-time, even though mass customization typically requires firms to reduce lot sizes and standardization [START_REF] Blecker | Mass customization: challenges and solutions[END_REF]. However, besides this large economic benefit of modularity, the use of modular product architectures also carries environmental implications: whereas a modular product might be more environmentally-friendly in terms of maintenance and its end-of-life treatment, it carries negative environmental impacts for the product design. Modular products are always inferior to integrated product designs in terms of weight and performance. Hence, more material resources are required for a product that is designed in a modular way [START_REF] Ulrich | Product design and development[END_REF][START_REF] Petersen | Is mass customization sustainable?[END_REF].

Lastly, an additional negative effect of MC can be assumed with regard to product design: the design phase is not only the initial stage of a product lifecycle, but can also be regarded as an essential step in a closed-loop lifecycle that merges the BOL of a new product with the end of life of a former product [START_REF] Clark | Design for Sustainability: Current Trends in Sustainable Product Design and Development[END_REF]. In this context, the implementation of a closed-loop lifecycle can be realized more easily in a mass production system than in the context of MC, as mass production deals with more standardized products. Whereas the combination of the EOL product and the new product is standardized in mass production, a mass customizer will be confronted with new combinations of old and new products with every customer.

Impact Factors in the Manufacturing Phase

Typically, manufacturing companies focus on waste reduction during production, when they pursue the issues of environmental and social sustainability for the first time. According to the National Council of Advanced Manufacturing (2009) sustainable manufacturing refers to the "creation of manufactured products that use processes that are non-polluting, conserve energy and natural resources, and are economically sound and safe for employees, communities, and consumers" [16].

Similar to the situation in the design phase, the implementation of Mass Customization shows controversial effects on the manufacturing processes in terms of environmental and social sustainability. However, it has to be noted, that the most important environmental impact factor of MC can be observed in the context of manufacturing: most MC companies operate a so-called X-to-order fulfillment strategy. This means that products are produced only after a respective order has been received from the customer. This approach prevents overproduction, as only those goods are manufactured that are actually needed by the customers. This results not only in a significant decrease of waste in terms of unwanted products, but also in a much lower level of energy consumption for the overall production. According to a 2009 estimation, 300 million pairs of shoes are over produced each year. Considering the energy required to produce each pair of shoes, the total energy consumption to manufacture all these unsold pairs of shoes equals 14% of the annual energy consumption of Switzerland [START_REF] Boer | International cooperation on sustainable manufacturing[END_REF]. This study shows that Mass Customization indeed has a major beneficial impact on sustainability in terms of manufacturing.

On the other handas mentioned abovethere are also negative aspects to MC manufacturing. For example, it has to be acknowledged that the realization of customized goods typically consumes more energy and resources than the manufacturing of massproduced products. Coming back to the example of shoes, every customized pair requires an individual type and cut of the leather, while for a standard pair of shoes the same type and cut of leather can be used. In consequence, manufacturing processes and the usage of raw material can be optimized in mass production and overall a lower consumption of raw materials and energy can be realized [START_REF] Brunø | Sustainability evaluation of mass customization[END_REF]. Hence, the increase of manufacturing complexity that results from an increase in product variety leads to a negative environmental impact of MC.

Besides these environmental aspects, the implementation of Mass Customization also shows social impacts in the manufacturing phase: whereas the rise of mass production has led to an increased used of offshoring of manufacturing, it can be observed that MC oftentimes goes along with more localized manufacturing concepts. As the products in MC are highly customized, fast response times and local distribution channels are of higher importance for manufacturers than in the context of mass production. Therefore, the implementation of Mass Customization carries the beneficial social impact factor of building and protecting a healthy, local job base.

Impact Factors in the Distribution Phase

Due to its typical x-to-order fulfillment strategies, the implementation of MC also requires new approaches for the distribution of final products, which in turn result in particular impacts on environmental sustainability. As in most cases of MC production can only start after the customer order has been placed, the customer cannot directly receive the product at the point of sale. Thusirrespective of whether the order was placed in a store or via an online sales channelmost MC companies have to realize home delivery for individual products. Naturally, such individual shipments of products require additional resources in terms of packaging and energy consumption [START_REF] Brunø | Sustainability evaluation of mass customization[END_REF][START_REF] Petersen | Is mass customization sustainable?[END_REF]. Moreover, this single batch delivery also leads to the consequence that each product is shipped individually, instead of transporting a larger batch of products to a store or distribution warehouse. Subsequently, a higher number of delivery operations is needed and hence more transportation emissions have to be expected. On the other hand, if MC was realized as an online retail business, customers do not have to travel to a store for picking up the final product. This suggests that MC may also have a positive environmental effect in terms of the distribution phase [START_REF] Brunø | Sustainability evaluation of mass customization[END_REF].

Additionally, the overall environmental impact of the distribution phase depends largely on the distance between the production site and the respective customers. A study by Kleer and Steiner, for example, shows that for a manufacturer of individualized shoes the individual shipment of products from the production site in China to the customers in Europe makes up a considerable part of the overall CO 2 emissions of this specific business model [START_REF] Kleer | Mass Customization: Bridging Customer Integration and Sustainability?[END_REF]. However, if MC is realized in combination with a localized productionfor example in the form of so called micro factories [39]the negative environmental effect of individual distribution can be strongly mitigated. In such a case, the distribution distance could be reduced significantly and would result in lower energy consumption and less emissions during the distribution phase [START_REF] Reichwald | Distributed mini-factory networks as a real-time enterprise: concept, flexibility potential and case studies[END_REF].

Lastly, the impact of reverse logistics is a critical point with regard to the distribution phase. Generally speaking, MC companies enjoy a less complicated distribution system in terms of reverse logistics: as MC products are tailored to the specific needs of individual customers, it is rather difficult to apply a return policy for these products.

The lack of such a return policy has its own controversial impacts in terms of environmental sustainability: on one hand, companies do not have to deal with reverse logistics, as customers cannot return the goods. This significantly reduces the level of energy consumption and transportation emissions. On the other hand, the lack of a return policy could also result in an increase in the level of waste: a customized product that does not meet the expectations of the customer, for whom it was customized, will most likely be disposed without being used, because it simply is not compatible with the needs of any other customer. This limitation towards re-use of the product may thus be regarded as a negative impact that results from the specific role of reverse logistics in mass customization.

Conclusion

Mass customization is mainly recognized as strategy to fulfill the individual needs of the customers in an efficient manner. The increasing interest of customers in involvement in the design phase and creating a customized product has made MC a proper business model and an attractive trend for many companies. Nevertheless for most companies, specially manufacturing companies, it is not the only trend to be followed. The increasing importance of sustainability both among customers and governments has pinpointed it as a critical point of attention for manufacturing companies including MC firms. In this paper we try to target this topic by having a closer look to the concept of Mass Customization from the sustainability point of view, both environmental and social. The paper tries to discover the potential interdependencies between MC and sustainability and eventually explore the environmental and social impacts of Mass customization. Following the product lifecycle management approach, the study is particularly focused on the beginning of life of MC products consisting of three main stages namely, design, manufacturing, and distribution. The analysis reveals that while in some aspects MC can act as a positive driving force for sustainability, in some another aspects it could cause challenges for sustainability.

For instance, from an environmental point of view, the modular architecture of a MC product can be seen as a significant positive driver for sustainability positive impact factor for sustainability due to facilitating of disassembly and therefore implementation of sustainable waste management strategies such as re-manufacturing and redesign at the end of the life of the product. However, from a different perspective, the customized nature of MC products makes them very single customer oriented and approximately impossible to be re-used by another customer. The elimination of reusing as a proper waste management strategy at the EOL phase, would lead to an increase in waste and a shorter lifespan of the MC products.

On the other hand, from a social perspective MC seems to be a more a positive driving force. Thanks to the co-design process, the strategy benefits customers, especially those with special needs (i.e. disabled customers), through providing them with products which are designed to satisfy their specific requirements in terms of function, performance or aesthetic. Meanwhile it would result in creation of more local jobs. Consequently, it is not possible to label Mass Customization as a sustainable or nonsustainable strategy. The environmental and social impacts of Mass Customization mark it as a bilateral business model. In fact, the challenge for the MC enterprise is to realize the trade-off and try to implement MC in a more sustainable manner.