Green Lean Six Sigma implementation framework: a case of reducing graphite and dust pollution

ABSTRACT

Modern organisations are in search of initiatives which will enable them to be sustainable as well as gain a competitive advantage. Lean, Six Sigma and Green initiatives are some of the widely used tools which aid the organisation to be sustainable. Recent studies have suggested that the integration of Green and Lean Six Sigma (LSS) will create a powerful methodology and help organisations to be sustainable. Yet, many organisations have found it difficult due to the lack of a generic implementation framework, which can be used for any processes and cultural context. The purpose of this study is to answer the research question: how to implement a sustainable Green LSS initiative in the organisation. Through a critical analysis of previous literature, an implementation framework is developed and practically implemented through a case study to reduce the graphite and dust pollution in a mine in India. Within case analysis, it is conducted to develop propositions, future research directions and managerial implications. This is a first study to develop and practically test a generic implementation Green LSS framework.

KEYWORDS:

• Green manufacturing
• Lean
• Six Sigma
• Lean Six Sigma
• implementation framework

1. Introduction

Numerous efforts are made by the organisations to include sustainability efforts in different areas of the business due to the regulatory pressures, corporate social responsibility or increasing public interest (Garza-Reyes 2015a; Cherrafi et al. 2017; Erdil, Aktas, and Arani 2018). In operations management, the concept such as green manufacturing is used to suggest strategies which are mindful of environmental impacts of production and operations (Deif 2011). The primary goals of such initiatives are minimising resource use, waste and pollution (Deif 2011) or in other words improve the environmental performance of the organisation. The environmental performance is a multidimensional phenomenon and can be broadly assessed based on five major broad dimensions such as decreasing emissions, decreasing energy consumptions, decreasing business waste, decreasing environmental waste and increasing environmental cost (Chugani et al. 2017; Kazancoglu, Kazancoglu, and Sagnak 2018). Among the plethora of methods to improve the operations, the Lean and Six Sigma are widely used in the pursuit of green manufacturing initiatives (de Freitas, Costa, and Ferraz 2017). Lean is used by the organisations to generate value by improving the process flow and lead time by identifying and reducing waste from the processes. Six Sigma creates value through consistent process output by identifying and reducing variation (Kazancoglu, Kazancoglu, and Sagnak 2018). The integration of Lean and Six Sigma has resulted in fewer defects and rework, lower levels of inventory, faster production, less space requirement, less transportation, less waiting and increased employee motivation (Erdil, Aktas, and Arani 2018). Together they also create a powerful strategy termed as Green Lean Six Sigma (Green LSS) (Garza-Reyes 2015a; Cherrafi et al. 2016, 2017) when used to meet the green goals. Nevertheless, some studies also advocate numerous challenges faced by the organisation while implementing Green LSS due to lack of a generic implementation framework (Cherrafi et al. 2017). Another point to deliberate is a necessity for a framework for implementation of Green LSS which can be used in different processes, organisation cultures and sectors. Also, there is a need for a model which is simple and easy to implement. Furthermore, the processes which are sensitive have also the ability to impact society (Sony 2019b). Thus, there is a need for an implementation framework for the successful application of Green Lean Six Sigma in organisation. This study proposes to fill this need. The motivation of this research, therefore, is to investigate the research question:

RQ: How to implement a sustainable Green Lean Six Sigma initiative?

In this context, we aim to achieve the following research objectives such as to (1) develop a generic framework to implement Green LSS in organisations, (2) present the implementation of this framework in a practical manner through a case study and (3) draw generic propositions and future research direction from the case study. The paper is organised as follows: literature is reviewed in the next section to build a conceptual model. It is followed by the case study, guidelines for the proposed framework, scope for future research, implications for the organisations, conclusion and limitations.

2. Literature review

Lean and Green has been one of the answers for environmental sustainability (Cherrafi et al. 2017). The combination of Lean and Green seems to be a natural combination (Garza-Reyes 2015b). The extensive literature reviews on Lean and Green proves that companies which are Lean can simply integrate Green practices and improve their sustainable performance. It further depicts that there is an intrinsic relationship between Leans and Green. Also, Lean is successful when used for reducing social and environmental negative impacts. The integration of Lean strategies benefits the firms. Likewise, when Green and Lean is implemented simultaneusly  in an organization it will have a positive impact when implemented together (Garza-Reyes 2015a; Cherrafi et al. 2016). However, one of the arguments against this integration is that existing limitations of Green and Lean linger. The integration of Six Sigma with Lean and Green results in powerful methodology (Garza-Reyes 2015a). Lean can identify and eliminate waste (Klotz, Horman, and Bodenschatz 2007). The limitation of Lean is that it does not explicitly take into consideration the environmental aspects (EPA 2003). The integration of Lean and Green was proposed to fill this limitation of Lean (Garza-Reyes et al. 2014; Pampanelli, Found, and Bernardes 2014; Duarte and Cruz Machado 2017). Verrier, Rose, and Caillaud (2016) proposed an implementation structure to a Lean and Green methodology based on the seeking and eradication of wastes in production processes. A Green and Lean model for business sustainability is an important indicator for a resource-efficient and green business (Duarte and Cruz-Machado 2017). The Lean and Green agenda can drive the integration of any continuous improvement activity throughout the organisation. They further suggest that the way this can be achieved is when continuous improvement activity is included in the Corporate Social Responsibility (CSR) plan (Chaplin and O’Rourke 2018). However, studies have shown that their integration has not helped the organisation to achieve sustainable performance (Cherrafi et al. 2017). Due to its data-driven, rigorous and methodological approach for problem-solving if integrated with Lean and Green, Six Sigma will be a tool that will help the organisations to achieve sustainable results (Garza-Reyes 2015a). Though Green Lean Six Sigma shows immense potential, it lacks a general implementation framework in companies where the processes are sensitive, and the organisational culture is different. The various implementation frameworks for Green Lean Six Sigma are summarised in Table 1.

Table 1. Previous studies on Green Lean Six Sigma implementation.

Sr No.	Author	Description
1	(Banawi and Bilec 2014)	Developed a framework in construction industry to integrate Lean, Green and Six Sigma for process improvement and minimisation of life cycle environmental impacts. The disadvantage of this framework was implementation time and considerable experience to ensure actionable results.
2	(Kumar, Kumar, and Haleem 2015)	A conceptual framework has been presented on mergers of Green Lean and Six Sigma, and they have proposed critical success factors for this framework. The framework was not tested.
3	(Sagnak and Kazancoglu 2016)	They suggested the integration of Six Sigma in order to overcome the limitations of Green Lean approach. In this framework, measurement system analysis and gage control are used as methodology to measure the variations of the process. They suggest a need for future frameworks to incorporate Six Sigma methodologies, such as Design of Experiments (DOE), DMAIC, process control charts or process capability index.
4	(Cherrafi et al. 2017)	They present a framework which methodically guides companies through 5-stage and 16-step process to effectively integrate and implement the Green, Lean and Six Sigma to improve their sustainability performance. The limitation of this framework is that sensitive processes may be difficult to improve using this methodology
5	(Sreedharan and Raju 2018)	They explored the structural attributes and obstacles in the public services and developed a Green Lean Six Sigma (GLSS) model for the public sector.
6	(Kaswan and Rathi 2019)	They study the enablers of GLSS implementation using Interpretive Structural Modelling. The proposed model was developed based on expert’s opinion and needs to be tested pragmatically to strengthen the findings of the present work.
7	(Hussain et al. 2019)	The barriers to Green, Lean and Six Sigma, driving and dependence power and their interrelationships were studied with respect to Pakistan construction industry.

A Green Lean Six Sigma (GL2S) framework was proposed by Cherrafi et al. (2017) to effectively integrate and implement Green and Lean Six Sigma in companies with different processes and organisational cultures. It also aims to increase productivity in the consumption of resources and reduce environmental and social impacts. They advise that some sensitive processes are difficult to be improved by this method. In another study, a five-phase implementation methodology for Green LSS was suggested. It was adapted from the work of Mostafa, Dumrak, and Soltan (2013), and the phases were readiness for LSS and sustainability initiative, conceptualisation, implementation design, implementation and evaluation and sharing knowledge for continuous value creation. This model is generic in nature and does not account for the culture. The organisation culture is another significant facet when implementing Green initiatives within the organisation (Harris and Crane 2002).

3. Proposed Green LSS implementation model

The Lean and Six Sigma models are very popular among the academicians and practitioners. The Lean implementation is revolving around five principles: (1) specify a value from the customer perspective, (2) align the value stream with customer values, (3) create the flow, (4) pull on demands and (5) create perfection (Womack et al. 1990). The Six Sigma follows a standard five-stage cycle which consists of (1) define the critical to quality characteristics (CTQ), (2) measure the problem, (3) analyse the problem, (4) improve – to eliminate or reduce the cause and (5) control the improvement so that the problem is solved and new order is frozen (Kwak and Anbari 2006; Schroeder et al. 2008). The analysis of studies which have implemented the LSS methodology primarily has its application through a DMAIC approach. Such an approach focusses on the quality improvement aspect and reduced the focus on Lean. Due to the quality focus, most tools and techniques used in these models were Six Sigma oriented. Nevertheless, such an approach limits the capability of LSS due to its orientation towards quality (Thomas et al. 2016). In Green Lean Six Sigma, there is a need for a methodology of implementation which can simultaneously extract the capabilities of Lean and Six Sigma. Thus, an integrated Lean Six Sigma approach would be beneficial when Green initiatives are the overarching framework for its operation. This approach has many advocates who suggest that such an approach will be beneficial to improve overall supply chain performance, reduce supply chain inventories and reduce throughput rates, holistic performance and environmental sustainability (Christopher and Rutherford 2004; Arnheiter and Maleyeff 2005; Thomas et al. 2016; Powell et al. 2017). The green initiatives are measured by the environmental performance. It is depicted in Table 2.

Table 2. Green initiative measures of environmental performance (Kazancoglu, Kazancoglu, and Sagnak 2018).

Green initiative measure	Description
Decreasing emissions	Due to reduction in greenhouse gases and air emissions
Decreasing energy consumptions	Reduction in terms of energy utilisation ratio, usage of green fuels and less consumption and usage of alternative energy fuels
Decreasing business waste	In terms of reduction in solid, liquid or water waste, the total flow quantity of scrap, waste generated, the percentage of materials recycled or reused, the total amount of hazardous and toxic materials, usage of hazardous materials and compliance of effluents with local and national authorities
Decreasing environmental cost	In terms of the cost of scrap, cost of rework, the additional cost of environmentally friendly products, disposal costs, recycling costs, cost of waste treatment, waste discharge fee, environmental accidents fine, cost of energy consumption and frequency of environment accidents
Increasing environmental revenues	Increase in revenues from green products, the sale of recycled materials and scrap, the sale of scrap and used materials, the sale of excessive inventories and materials and the sale of excess capital instruments

Figure 1 depicts the proposed GLSS framework. In this implementation framework, the DMAIC approach is implemented on each Lean thinking cycle. This approach is chosen because of the simultaneous implementation of Lean and Six Sigma. This framework rests on the organisational culture. Organisational culture is shaped by values, attitudes and expectations that are held in common by the members within the organisation (Goffee and Jones 1996; Schein 2010). It can also be seen as a pattern of unconscious basic assumption for members within the organisation (Schein 2010) and which are further shared by behaviours and artefacts (Brettel, Chomik, and Flatten 2015). Organisational culture has an impact on both at the organisation and at the employee levels. It can also be considered as a force which holds the organisations together and is, therefore, a main element for the success of the organisation (Goffee and Jones 1996). An organisation whose policies, visions and missions are directed towards sustainability and green management will have a culture within the organisational ecosystem which makes each and every employee to orient their actions towards sustainability (Haugh and Talwar 2010; Chen 2011; Chang and Chen 2013). Consequently, this model considers organisational culture as the central tenant which will bind the Green LSS initiatives. The green initiatives are implemented in each of the phases of LSS implementation, and it will create an environmental performance in terms of broad themes such as decreasing emissions, decreasing energy consumptions, decreasing business waste, decreasing environmental costs and increasing environmental revenues.

Figure 1. Green Lean Six Sigma implementation framework.

The proposed framework can be used by the organisation to integrate Green Lean Six Sigma in a systematic manner to achieve environmental performance. The framework in Figure 1 can be implemented in a methodological manner. The entire framework rests on organisational culture.

Step 1: The first step before the introduction of this framework is to examine the organisation culture in terms of Greening the organisational culture. A dramatic cultural change is required for the organisation in order to respond to environmental challenges if the existing culture does not incorporate it. The greening cultural fix methodology should be implemented in two stages. In the first stage, a top-down approach from the top management to shop floor the greening culture should be disseminated by the organisation. This strategy will impart in every employee a sense of oneness towards the greening cause.

Step 2: In the second step, greening culture should be promoted at the individual employee level to create a sense of understanding about the environmental problems. Both these steps will help the organisation to attain the greening of the organisational culture.

Step 3: Lean Six Sigma should be implemented in every project an organisation undertakes. Each project should be evaluated in terms of operational and economic and on the five dimensions of environmental performance such as decreasing emissions, decreasing energy consumptions, decreasing business waste, decreasing environmental costs and increasing environmental revenue. The LSS application would conduct in five Lean cycle stages complimented by DMAIC process on each phase.

Step 4: Stage 1 of Lean cycle will operate for specifying value. DMAIC (Define Measure Analyse Improve Control) is implemented on stage 1 as it will help to understand the unique value of the product, service or process by considering the Green initiative measures.

Step 5: Stage 2 of Lean cycle is to map the value stream. DMAIC methodology is applied so that to enable Lean teams to understand how value flows through the organisation by considering the Green initiative measures.

Step 6: Stage 3 of Lean cycle is to create flow by analysing each step in the process by taking into consideration the Green initiative measures, finding ways to maximise efficiencies and reducing waste. DMAIC is applied to the flow cycle to stabilise the process.

Step 7: Stage 4 of the Lean cycle is to create a pull-on demand so that we have exactly the quantity the customer needs by considering the Green initiative measures. DMAIC is applied on the pull cycle to reduce variability on the pull cycle.

Step 8: Stage 5 of the Lean cycle is to seek perfection so that the most efficient process could be designed to create value. DMAIC application will stabilise the Lean cycle of perfection by considering the Green initiative measures.

4. Case study: reduction in graphite and dust pollution

To demonstrate the integration mechanism, a single case study approach is used. The primary research question in this case study was how to implement sustainable Green LSS for achieving a reduction in graphite and dust pollution in an open cast mine. In order to answer the ‘how’ question within a complex natural setting, case study research is one of the most suitable methods (Yin 2011). The specific research design is an embedded, single case study. Data were collected from the plant level as well as from the corporate level. One of the authors was working on the project, and hence, the data were collected for the entire period from 2012 to 2015. A single case study is used when the intention is to create a high-quality theory (Gustafsson 2017). In this study, it was intended to suggest the integration mechanism between Green and LSS. Another reason for a single case study was to have a deeper understanding of the exploring subject (Yin 2011) of the integration mechanism of Green and LSS. The case study took a longitudinal field study which is special case-based research that is designed to provide an in-depth study of change processes as they happen inside the organisations. The difference between a conventional case study and longitudinal case study is that the latter allows the researcher to observe the change process as it develops and unfolds in real time (Powell et al. 2017). Another feature of the single case study is that it richly describes the experience (Gustafsson 2017) of the integration mechanism of Green and LSS. Once a single case study is used, the authors can question the old theoretical relationships and explore new ones (Eisenhardt 1989; Denzin and Lincoln 2011; Yin 2011; Van Hout and Bingham 2013; Gustafsson 2017). The study adhered to the recommended structure for a single case study in terms of purpose, approach, process and quality control methodologies (Baxter and Jack 2008; Yin 2011). The interviews were conducted at the managerial level and plant level where the project was conducted by the second author. Five interviews each were conducted at the managerial level and plant level. Besides, all the 15 team members were interviewed subsequently after the implementation of the project. The rationale behind the process was to understand the lived-in experience of implementing the Green Lean Six Sigma project. The interview process was kept flexible, and open-ended questions were asked to elicit their responses about the process of implementation. The second author was working on the project and hence had access to all the members of the team, and hence, the interview was conducted in the organisational premises when the members consented. The three-phase interview protocol framework was used in the study. In the first phase, the authors tried to interview the participants by aligning the questions in line with the main research question. The second phase was devoted to constructing an inquiry-based conversation with the participants. In the third phase, the interview data were shown to the participants for verifying its correctness, thereby improving the credibility of the data collection process. The interviews were subsequently analysed. Likewise, secondary data such as project report, designs, charts and other communication pertaining to the project were analysed for further details. The company did not want to be identified due to undisclosed reasons; therefore, the pseudo name company X is assigned. Company X is one of India’s largest exporter of iron ore in the private sector. For over five decades, company X has been involved with iron ore mining. It is also involved in beneficiation and exports. The last two decades have seen the organization diversify into the manufacture of pig iron and metallurgical coke. The company has access to 250 million metric tons of reserves and resources of iron ore. It also operates a 280,000 TPY metallurgical coke plant and a 250,000 TPY pig iron plant in the area the case study was conducted. Though the companies' dust generation levels are below statutory norms, the presence of graphite and dust generation during desulphurisation operation creates annoyance in the hot metal handling area. Similarly, due to their environmental consciousness, the company has a new policy set in to reduce the dust and graphite emission in the hot metal handling and baghouse by 20% of the previous year.

4.1. Rationale for implementing Green Lean Six Sigma framework

Company X has been implementing Lean tools since 1999 and gained enough expertise in the implementation of Lean management. They have applied Lean with immense success in various operations and iron ore transportation logistics to save considerable financial savings. They were using various Lean tools such as Value Stream Mapping, Takt time, Heijunka, TPM and 5S for the company. Six Sigma was introduced in the year 2006, and its implementation has improved the quality of ore processed and waiting time for loading and unloading of ore transfer vessels for ore transportation through the sea. The second author who was working in the company was briefed by the company’s authorities on green orientation initiatives. After a detailed analysis for the data, the dust levels at the desulphurisation plant were found to be though below the target but high compared to other plants. After a detailed meeting with the top management and series of presentations, it was decided to reduce the dust pollution levels by 20% using Green LSS framework. On the operational level, reduction in graphite and dust level would improve the working condition within the organisation. The high graphite and dust levels also had an impact on the employees and machines. Thus, there would operational and maintenance benefits. The graphite and dust level reduction will further reduce the environmental impact also, and the society at large will also be benefitted. A group discussion of various departments was carried out, in order to note down the challenges of day-to-day working in the desulphurisation plant. The members were selected through a process where due weight was given to LSS certification and experience. The team members included green, black and master black belts and others. There were 14 team members. All were male. Ten of them were not awarded any LSS certification but were employees who had considerable technical and work experience in the plant. Two were Green belts and one was a black belt and one Master black belt. In the proposed implementation framework, the importance of Green and Black belts is an important criterion because the role of these employees in the success of the project is perennial.

4.2. Phase 1: specify value

The DMAIC methodology was primarily used in this phase. A group discussion of all the employees working in the desulphurisation plant was conducted to understand their needs regarding the graphite and dust pollution levels. The company doctor and other health professionals who are stationed in the mine were also contacted to understand the nature of the impact of graphite and dust pollution levels. The key critical to quality characteristics to be monitored was graphite and dust measurement in terms of μg/m³ in four strategic locations which was found to be high. These locations were dust emission at slag dryer, dust emission at coke screen, dust emission at baghouse and dust emission at iron ore screening. In the measure phase, stakeholders were shown the existing levels of graphite and dust pollution. It was further agreed upon that a reasonable target reduction of 20% was agreed upon. In the analyse phase, the stakeholder requirement was further analysed to meet those requirements which can be met. In the improve phase, the key investments were identified, and they were further balanced with return on investment. An important finding was ‘Metal transfer from the ladle to ladle due to various reasons such as clearing ladle bottom jam, metal mixing of both the furnaces to get metal in grade, to avoid ladle getting jammed due to cold metal were identified to be a major cause for generation of graphite’. It was further identified that dust emission at slag dryer, dust emission at coke screen, dust emission at baghouse and dust emission at iron ore screening the average levels at present were found to be 2.68, 2.29, 1.71 and 1.92 μg/m³. The stakeholders agreed on a realistic target for next one year to be 2.15, 1.83, 1.37 and 1.92 μg/m³. The tools used in this phase are group discussion, brainstorming, five whys, smart goals, project charter and statistical analysis.

4.3. Phase 2: align the internal value stream

The DMAIC approach was used here to develop environmental VSM (EVSM) (Alvandi et al. 2016) for each of the processes under consideration such as dust emission at slag dryer, dust emission at coke screen, dust emission at baghouse and dust emission at iron ore screening. The graphite and dust pollution levels at each subprocess along with time were noted for current VSM. A future VSM based on the reduction targets was also constructed. The VSM was further analysed in detail, and the following measures were found to be suitable for implementation. A multi-voting system was employed for prioritising the options.

• Metal transfer from the ladle to ladle due to various reasons such as clearing ladle bottom jam, metal mixing from both the furnaces to improve the metal grade and ladle jam due to cold metal was identified to be a major cause for generation of graphite.

• Metal transfer from the ladle to ladle is done only in extreme condition.

• Ladle bottom jamming is reduced by removing one ladle from circulation.

• Each instance of metal transfer is logged, and data are analysed to find out the alternative. Dust generation during desulphurisation.

• Modify the existing de-dusting system of desulphurisation unit as an immediate solution.

• Improved process design has been proposed.

• Stirring of baghouse debris for cooling before loading is another factor leading to graphite generation.

• Slag pot dumping trials taken, and purchase order for slag pot raised.

• As an immediate solution till the receipt of slag pot, baghouse debris is soaked with water before loading.

The improve phase was used to categorically analyse these options and prioritise them for the implementation. The control phase consisted of steps to develop specific standard operating procedures (SOP) in terms of metal transfers to be done in extreme condition. In addition, other solutions were also given control documentation. The tools used in this phase are EVSM, multi-voting system, SOP, Takt time and waste identification including green wastes.

4.4. Phase 3: create the flow

The DMAIC approach is used here to create an improved flow for metal transfer. In order to do so, the team designed a new process wherein the ladle to ladle metal transfer is reduced. The reasons for the ladle to ladle transfer such as clearing ladle bottom jam, metal mixing of both the furnaces to get metal in grade and avoiding ladle getting jammed due to cold metal were eliminated with the improved design. Various tools such as discrete event simulation and process charts were used in the analyse and improve phases. In the control phase, various SOP was charted which will help to analyse the flow further. The tools used in this phase were process charts, discrete event simulation, Pareto diagram, SOP and cause–effect diagram.

4.5. Phase 4: pull-on demand

The DMAIC process is also applied here. A pull of demand system was created for the metal transfer in the desulphurisation plant based on the value need for the next process. The pull system was created for all four processes, i.e. dust emission at slag dryer, dust emission at coke screen, dust emission at baghouse and dust emission at iron ore screening. The pollution levels were measured at these levels and were further analysed using five whys. This helped to further implement solutions when there is demand variation. Some solutions used were debris cooling/stirring near pig casting machine spout, spray/mist arrangement being made at tail end, high-volume vacuum cleaner with low-diameter pipes and modified attachments to be used for periodic cleaning of the structures, roof spray operating frequency increased and windshield erection along boundary wall, which will help to reduce graphite and dust pollution. The tools used in this phase include five whys, demand analysis, bottleneck analysis and so on.

4.6. Phase 4: create perfection

The DMAIC process is also used here. The intended target values are also set for all four processes, i.e. graphite and dust emission at slag dryer, dust emission at coke screen, dust emission at baghouse and dust emission at iron ore screening. In the measure phase, the levels were measured at these sites continuously and analysed further for improvement. This created a state wherein the process would be further improved. The perfection is a cyclical process, and it would need DMAIC applied in a continuous manner. The results are tabulated in Figure 2.

Figure 2. Performance improvement in graphite and dust levels.

The result was tabulated after one year of the implementation, and it was found that in all four areas, the results have met the target. The tools used in this phase include SOP, control charts and Lean audit.

5. Guidelines for the proposed framework

The interest in the sustainable organisation has been growing in recent years. Organisations can contribute to sustainable development by simultaneously performing on the economic, social and environmental dimensions (Elkington 1998). From the operational perspective, all operational activities must be aligned in all three dimensions of sustainability to contribute to the concept of sustainable enterprise. In order to be competitive, organisations are using business improvement strategies. LSS is one of the most widely used business improvement strategies in the organisation (Pepper and Spedding 2010; Antony, Snee, & Hoerl, 2017; Sony 2019a). The disadvantages of LSS are that it is not predominantly predisposed towards green initiatives (Banawi and Bilec 2014; Sony 2019a). Therefore, LSS can be combined with Green initiatives within the organisations to create a powerful business improvement strategy (Garza-Reyes 2015a). The purpose of this study is to answer the question of how to implement a Green Lean Six Sigma in an organisation. Through a literature review, this study develops an implementation framework for the Green Lean Six Sigma. Subsequently, the framework is applied to a single case study in an open cast mine in India to reduce the graphite and dust pollution. The first step in implementing LSS is specifying the value. The value is something which is defined by the customer needs for a specific product. The DMAIC approach is applied to analyse the specific value as defined by the customer. In this phase, care should be taken to understand that to meet this value, how will it perform on the environmental performance dimensions. The main criteria for the assessment of environmental dimensions should be decreasing emissions, decreasing energy consumption, decreasing business waste, decreasing environmental cost and increasing environmental revenues. An employee from the organisation reported ‘Customer needs are most important for the organization. It must be met. But organization should also analyse in detail that to meet the customer needs what would be the impact on the environment. I want to state an example from my company, where our customer wants large consignment of iron ore to be exported but if we don’t mine sustainably, we are not to give something for our kids’. This thinking suggests a need for the organisation to analyse the existing customer needs harmonised with the environmental impact and embrace the green initiatives to mitigate those; therefore, it is proposed:

P1: The value which is specified by the customer should be investigated through a DMAIC process for strategies for decreasing emissions, decreasing energy consumption, decreasing business waste, decreasing environmental cost and increasing environmental revenues.

To create the specified value, the organisation must go through various processes (Womack and Jones 1997) to build a value stream. The DMAIC process should be used to create the current and future value stream by incorporating the environmental dimensions. To get a true picture of current and future state VSM, each process should also consider the five dimensions of environmental performance, and the most widely used tool is EVSM (Alvandi et al. 2016). During the interview, one employee remarked ‘Value stream map is very important tool to chart the process of meeting customer value. However, we need to be creative while using the conventional value stream map to include things which will benefit the environment’. The within-case analyses and interviews suggest the need for the organisations to map the value stream by incorporating environmental dimensions; therefore, it is proposed:

P2: The organizational processes should be mapped for the value it creates though Sus-VSM, using DMAIC methodology by considering decreasing emissions, decreasing energy consumption, decreasing business waste, decreasing environmental cost and increasing environmental revenues.

Creating a smooth flow is a vital step in the application of Green LSS. The design of value-added steps must be designed in a manner so that minimum hindrance exists through a DMAIC process. The smooth flow should also be aligned with the five principles of environmental performance. A smooth flow will result in reduced energy consumption (Ball 2015) and other environmental benefits. An employee was asked about the importance of creating smooth flow ‘Being a lean professional we were designing the flow based on the seven-waste prescribed in lean methodology. But in the modern organization, due to the implementation of Green initiatives, streamlining the flow by taking into consideration the reduction in harmful gases for the atmosphere is very important’. The importance of creating a smooth flow by considering the environmental dimensions is very significant, leading to propose:

P3: The processes need to be designed to create a systematic flow through a DMAIC methodology by considering decreasing emissions, decreasing energy consumption, decreasing business waste, decreasing environmental cost and increasing environmental revenues.

The pull system designed should be done through a DMAIC process to respond to the customer’s needs by considering the five environmental dimensions. A well-designed pull system will help the organisation to perform well on the environmental dimensions (Gogula, Wan, and Kuriger 2011). Employee remark on the pull system was ‘Customers are very alert on the products which will save our environment. There is a huge demand for such products. Organizations can make us this customer need to design systems which will benefit all of them’. The organisations need to design a pull system that will take into consideration the environmental dimensions as such; we propose that:

P4: The pull system must be designed through a DMAIC methodology by taking into consideration environmental performance dimensions such as decreasing emissions, decreasing energy consumption, decreasing business waste, decreasing environmental cost and increasing environmental revenues.

The basic idea behind creating perfection is to continuously work to reduce/eliminate waste and variation by considering all the five environmental performance dimensions. An employee clarified ‘Creating a state of perfection by considering the environmental performance is a challenge for the organization. It is an idealistic thing to start an initiative and another thing to achieve perfection’. The continuous improvement philosophy should also incorporate the environmental dimensions for the success of Green LSS initiatives.

P5: Organizations should continuously strive to create perfection through a DMAIC methodology to decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues.

The success of Green LSS will be contingent on the organisation culture (Jose Chiappetta Jabbour 2011). In each phase of the implementation of Green LSS, the organisational culture will help to shape the underlying principles. An employee commented ‘A company which has a vision, mission and predisposition towards green initiatives will be in a better position to implement such Green LSS initiatives. Because every employee will be motivated and brainwashed with company culture to save energy or reduce greenhouses gasses’. Therefore, for the successful implementation of Green LSS framework, organisations need to instil a policy, visions and missions which are directed towards sustainability and green management.

P6: The successful implementation of Green LSS framework will be contingent on an organizational culture which is receptive towards the green initiatives.

6. Future research direction

Previous studies have suggested a need for research for Green LSS implementation framework, which is generic and can be used in different context and in sensitive processes (Garza-Reyes 2015a; Cherrafi et al. 2017). This study is an initiative to fill the research gap, and each of the propositions developed in this study could be further empirically tested. The future research  should be devoted to selection of cases wherein the organisational culture is not receptive to green initiatives. The analysis should be conducted in longitudnal manner so that it  will help to understand the role of organizational culture in greening initatives. Such a case study will help to unearth initiatives for the implementation of Green LSS. Further, such a study will help to ascertain the role of organisational culture to promote Green LSS in a sustainable manner. In addition, a qualitative study may be conducted to explore the critical success and failure factors for implementing the Green LSS through the experience of various stakeholders. The methodology for the combined usage of LSS tools with green initiatives for decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues is in the preliminary stages, and future research should clarify in a systematic manner so that practitioners can easily deploy this initiative in different organisations. The research on sustainable VSM mapping should include a step-by-step charting process so that the specified value in terms of green initiatives such as decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues can be mapped. Studies can also focus on the methods to create a systematic flow in organisations while considering green initiatives such as decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues. A step-by-step methodology will help the organisations to streamline their flow patterns. Though there are guidelines for designing pull systems based on Lean principles (Marvel and Standridge 2009; Lu, Yang, and Wang 2011), nevertheless, due to the implementation of green initiatives such as decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues, the existing pull system principles should be revisited. Research in this direction will also be perennial for the successful implementation of Green LSS, and there is hardly any research in the direction at present. Creating a state of perfection wherein organisations will accomplish the stated objectives on the five environmental dimensions will help in studying the journey from the present state to the desired state in methodological means. A stage model may be advanced so that organisations can map the journey of organisations towards perfection. Empirical studies may also be directed to test the relationships between Green LSS and the five dimensions of environmental performance to test for any possible role of any mediators and moderators in this relationship. Besides, an organisational assessment model which will help the organisations before implementing Green LSS to assess the organisational readiness to implement green initiatives for decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues will be advantageous for new organisations which are implementing Green LSS.

7. Implications for the organisations

The proposed Green LSS model will help the organisations in a methodological manner to implement the Green LSS initiatives within the organisation. Organisations should analyse the specified value defined by the customer, through a DMAIC process on the five dimensions of environmental performance. Some organisations may perform well on some dimensions and perform weakly on the others. In order to realise the full potential of Green LSS, the five dimensions of environmental performance should be utilised to specify the customer value. The organisations may subsequently utilise the environmental value stream mapping to chart the entire process for the specified value in a sustainable manner. It should be followed by streamlining of the material flow sustainably. Eventually, a pull system may be designed along with that a continuous effort should be created to create a state of perfection. The proposed implementation framework is designed with a thinking that Lean process will reduce the waste and six sigma methodology will eliminate the variation systematically in line with green initiatives such as decrease emissions, decrease energy consumption, decrease business waste, decrease environmental cost and increase environmental revenues, making this initiative a viable proposition in the long run. Organisations while using this implementation framework should be vigilant about the existing organisational culture within the organisation towards green initiatives. It is tough to change the organisational culture overnight; yet, strategies for changing the shared perception of employees should be introduced during the early phases of the implementation of this Green LSS framework. The organisational culture takes time; therefore, it is advised for the successful implementation of Green LSS, and this exercise should be conducted immediately in an effective manner.

8. Conclusion and limitation

The sustainable organisation must perform healthily on the environmental dimensions. This study introduces a framework for implementing the Green LSS within the organisation to accomplish the green objectives on the five dimensions of environmental performance. A single case study approach is used to implement the Green LSS framework within the organisation to reduce the levels of graphite and dust pollution. Within case analysis, it was conducted, and it has proposed six propositions which can be used by the future researchers. The organisational and academic implications are further delineated from the case study.

The research findings are tempered by some limitations. A single case study was envisaged as being an implementation framework it takes a considerable time for implementation and analysis considering many variables. Thus, the generalisation of the results should be done only after further studies in the different industrial setting. There is a possibility that different sectors may attach an order of importance of the five dimensions of environmental performance; therefore, the model needs to be retested in these sectors. Second, the study should be replicated in a multinational setting to explore the contextual and cultural influence on the framework.

Acknowledgements

The authors want to thank the management and all employees of the company who were very helpful during the case study process. Also, the authors express their sincere thanks to the anonymous reviewers for their constructive suggestion which improved this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Notes on contributors

Michael Sony

Dr.Michael Sony is at present a faculty at Namibia University of Science & Technology, Windhoek, Namibia. He holds a Ph.D. from Goa University, India. He holds a Master of Engineering in Industrial Engineering from Goa University. He passed a bachelor’s degree in Electrical Engineering in the year. He was earlier working in Goa Electricity Department, Government of Goa, India. He holds a Black Belt in Six Sigma. His research interest includes Quality Management, Industry 4.0, and sustainable operations.

Subhash Naik

Dr. Subhash Naik is a Heading the Process improvement & Business Excellence professional Globally. Presently working at Sterling & Wilson Pvt Ltd-market Leader in EPC segment. He is Holding Lean Certified Six Sigma Master Black Belt, Gold Medalist academically, Certified Project Management Professional, Champion in Lean Methodology, Operational Excellence, Change Management Professional. He is selected as International WHO’S WHO’S Professional from international society for inclusion in 2009 edition, Washington, USA. Dr. Naik have 17þ years Rich experience in Operational Excellence, Customer Service Delivery, Industrial Engineering, Business Excellence in a variety of leading roles and Responsible for Driving Strategic Transformation Projects on improving EBITDA.