Keywords

1 Introduction

The idea of sustainability is in effect at a policy level, but it needs to be expanded in the business sector. In addition, the firms must recognize and monitor the major implications of their various processes on the environment and various stakeholders from a sustainable development perspective to execute the guidelines of the Global Reporting Initiative (GRI) [9]. Progress toward sustainability further involves modernizing life cycle assessment processes and striving for sustainable goods [14]. Environmental conservation is the key to achieving this sustainable development goal. In addition to protecting the environment, evaluating economic aspects and impacts on society is also included in the outlook. The life cycle sustainability assessment system (LCSA) was, hence, proposed as it combines environmental security, economic outlook, and social equity. According to Guinée [5] and Guinée and Heijungs [6], it is possible to expand LCSA by incorporating environmental, social, and economic aspects and further expanding the boundary of a system from a micro-level (process-based) to a macro-level (economy-wide) study. These three dimensions are known as sustainability pillars, which involve the consideration of environmental, human, and economic resources, or the earth, people, and income in colloquial terms [3, 4, 7]. The dynamic relationships between the LCSA parameters also need to be understood and the mechanisms of causality between system parameters, such as economic, social, and environmental metrics, need to be studied to deepen the LCSA structure [13].

The LCSA tool is considered to be the best and offers the highest standard of evaluation among the existing environmental and sustainability tools [6]. The shift in perspective from environmental protection to economic and social protection is one of the key drivers for the introduction of the life cycle sustainability assessment (LCSA) [6] (Fig. 1).

Fig. 1
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Three dimensions of sustainability

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When the ‘Brundtland study’ [11] introduced the idea of sustainable development to the international community in 1987, it developed a new framework for economic growth, social inclusion, and environmental conservation. The ‘three pillars’ interpretation of sustainability, i.e. the environmental, economic, and social aspects, is the normative model, which is well embraced by industry and often referred to as the ‘triple bottom line’ [10]. The conceptual formula for the LCSA framework was given by Kloepffer [8] (Fig. 2), which was further improved as presented below:

$$ {\text{LCSA }} = {\text{ LCA }} + {\text{ LCC }} + {\text{ SLCA}} $$
Fig. 2
figure 2

Conceptual formula for LCSA

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where

LCSA = life cycle sustainability assessment

LCA = environmental life cycle assessment

LCC = life cycle costing

SLCA = social life cycle assessment.

2 LCSA Methodology

There are many approaches to perform the sustainability assessment, but the widely and commonly used methodology for evaluating the life cycle sustainability assessment is formed by combining the three life cycle techniques. Out of these three life cycle techniques, only LCA guidelines are defined by ISO 14,040, whereas for LCC and S-LCA, the methodological framework is still under development. Therefore, LCSA requires further improvement in the economic and social perspective, adding more accurate databases (especially for India) and understanding of establishing a relationship between the three dimensions of sustainability [1].

The LCSA framework consists of four phases that are (Fig. 3):

Fig. 3
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LCSA Framework

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  1. i.

    LCSA goal and scope

  2. ii.

    LCSA inventory analysis

  3. iii.

    LCSA impact assessment

  4. iv.

    Interpretation

2.1 LCSA Goal and Scope Definition

It is an important step in the LCSA process that helps to establish the study's context. It should include the following information—purpose of the study, target audience, defining the boundary, defining the functional unit, assumptions, and limitations (if any). LCA, LCC, and S-LCA (environmental) have different goals but while performing a combined LCSA, common goals and scope are strongly recommended.

2.1.1 Functional Unit

The functional unit serves as a foundation for inventory data collection and impact analysis. All the required data must be collected according to the functional unit. S-LCA does not need a functional unit because qualitative information is gathered and then translated to quantitative data for evaluation.

2.1.2 System Boundary

System boundary can be understood as a boundary or line that separates the process on which we want to focus. An attempt must be made to consider the phase, which has a maximum impact on the environment, economy, or society. When carrying out an individual assessment, each life cycle technique can have specific framework system boundaries based on its value for sustainability aspects. But there must be stages common for sustainable assessment.

2.1.3 Impact Categories

For an LCSA report, it is required that all impact categories that apply during a product's life cycle be chosen. When determining the impact categories, these should take into account the perspectives offered by each of the three approaches as well as stakeholder perspectives.

The major impact categories for each dimension are discussed below (Tables 1, 2, and 3):

Table 1 Description of impact categories for E-LCA . Source Acero et al. (2015)
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Table 2 Description of impact categories for LCC. Source Simões et al [12]
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Table 3 Description of impact categories for S-LCA. Source UNEP report [13]
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2.2 LCSA Inventory

It is the most time-consuming stage of LCSA. It involves the compilation and quantification of inputs and outputs for a product throughout its life cycle (ISO 14,044:2006(E)). The inventory data must be collected as per the functional unit chosen during the goal and scope process. Tables can be generated from the collected data, and interpretations can be made. The inventory's result offers information on all inputs and outputs in the form of a basic flow to and from the environment. (Fig. 4). For LCSA inventory, both qualitative and quantitative data are taken into account.

Fig. 4
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LCSA inventory

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Inventory is an interaction between the unit process and the external environment that can affect the sustainability aspects (environmental, economic, and social). Therefore, inventory data were collected individually for each life cycle attribute. It is also recommended that the inventory data must be collected according to the unit process and at the organizational level [13]. Quantitative data are collected for the LCA and LCC and qualitative data are collected for S-LCA, which is later converted to quantitative form to perform the analysis.

2.3 LCSA Impact Assessment

This step is intended for assessing the associated inventory with the environmental, economic, and social problems. This is comprised of three essential steps:

  • Choosing impact categories, indicators of that category;

  • The collected inventory data are grouped into particular impact categories during the classification process.

  • Impact measurement, in which categorized LCI flows are described in specific equivalence units using one of several possible LCIA methodologies, and then summed to produce a complete category of effects (ISO 14,044, 2006).

The impact assessment for E-LCA can be performed by using various LCA softwares such as SimaPro, GaBi, Open LCA, etc. which can access through a complete chain for a product or a process, It takes input (raw material requirement, the electricity required, power usage, water requirement, etc.) and output (products, co-products, emissions in the air, water, land, waste generated, hazardous waste generated, etc.), and assessment result is given based on this.

For LCC, impact assessment can be done in SimaPro software, and also there are various integrated LCA/LCC frameworks available that can help in performing the assessment. LCC is generally combined with LCA because both follow a quantitative approach and the same steps. For S-LCA, there is a database available known as SHDB (Social Hotspot Database), and there are manual approaches such as Sub Category Assessment (SAM) approach, which can be used to study the social impact.

2.4 Interpretation

The inventory analysis and impact evaluation phases are combined in the interpretation process. It is a structured methodology for defining, quantifying, reviewing, and analyzing data from the life-cycle inventory phase and/or the results of life-cycle impact evaluation. The analysis process produces a collection of conclusions and recommendations for the study. According to ISO 14,040:2006 should include the following:

  • Recognition of significant issues based on the results of the LCI and LCIA phases of an LCSA;

  • Assessment of the study using completeness, sensitivity, and accuracy checks; and

  • Guidelines, drawbacks, and assumptions.

3 Development in LCSA Tool

There are few areas identified by various authors, which need more developments for advancements LCSA framework.

  1. i.

    The relationship between the three pillars of sustainability is still lacking [5, 14]. One explanation for this is the existence of the metrics used in these methods, which vary from quantitative to qualitative, making aggregation difficult.

  2. ii.

    It is encouraged to build up more streamlined methods that analyze the system as a whole (rather than focusing on one aspect in more detail). Software and database companies are being asked to make user-friendly and low-cost techniques available to promote more LCSAs.

  3. iii.

    Adding the inventory databases from the developing countries and emerging economies for all the three life cycle techniques (LCA, LCC, and S-LCA) to make it more accurate and robust.

  4. iv.

    LCSA is a new area that needs to be discussed further, and it necessitates the active participation of stakeholders and policymakers in the interpretation phase.

  5. v.

    To prevent the unethical use of the tools, focusing more research on evaluating product effectiveness and sustainability.

  6. vi.

    Considering the perspective of future generations in future research, adoption of LCSA strategy to prevent generational trade-offs and to take into account the Brundtland principle of sustainable development.

4 Establishing Relationship Between Three Pillars of Sustainability

To establish a relationship between the three sustainability pillars, the concept of system thinking can be used. System thinking helps us to analyze interrelationships (context and connections), viewpoints (each participant has his/her unique view of the situation), and boundaries (agreement on scope, scale, and what might be an improvement) [9]. Hence by integrating system thinking into LCSA can help in integrating and establishing the relationship between three sustainability aspects. It will also act as a decision-making tool and will help in effective policymaking. It consists of the following steps:

4.1 Identifying Variables of the Process Chain

The process chain must be studied from a system dynamics perspective, taking into account the complex and causal relations between the environment, economy, and society. For each sustainability aspect of the process chain, the variables must be described based on the LCSA study performed. The variables can be identified from the impact assessment results, which show the most affected impact categories.

4.2 Creating a Causal Loop Diagram

A causal loop diagram lets one understand how different variables in a system are interrelated. The diagram is composed of a series of nodes and edges. The nodes represent the variables and the edges are the links that represent a relationship between the two variables identified for the study. The causal loop diagram presents the most important relations between identified parameters of the system and explained how system thinking can be used to present a clearer view of the interest system's underlying mechanisms and their impacts on different aspects of sustainability.

The causal loop diagram is composed of four essential components.

  1. i.

    Variables: The initial step in developing a causal loop diagram is identifying variables. For this study, the variables were identified from our LCSA study of crude oil in India.

  2. ii.

    Drawing Links: The next step is to draw links between the identified variables, filling it with the verb, and determining how one variable impacts the other. The links are labeled as ‘+’ ‘−’ or ‘s’ ‘o’. If variable B goes in the same direction as variable A, it will mark the relation between variable A and variable B with “s” (or “+”). If variable B moves in the opposite direction of A (i.e., as A increases, B decreases), the relation between A and B should be labeled with an “o” (or “−”).

  3. iii.

    Labeling the loop: In this step, we identify the behavior of the loop. There are two fundamental types of causal loops in systems thinking: reinforcement and balancing. If a change in one direction is amplified by any further changes, then it is a reinforcing loop. In balancing loops, alternating loops counter-shift in one direction with a shift in the opposite direction.

  4. iv.

    Talking with loops: By connecting various loops, we create a concise story for a particular problem. To ensure this, we must follow the links and capture the loop behavior.

5 Conclusion

Startups, government organizations, international cooperation agencies, and other societal entities will all benefit from LCSA in their efforts to generate and use more sustainable goods. This entails cost-effectively minimizing environmental pollution and the conservation of natural resources while also contributing to social well-being.

The discussed LCSA approach can be used to determine the sustainability of all goods and processes, providing useful data to policymakers. Since the LCSA framework is still in the developing phase, more developments are needed.

The integration of system thinking with sustainability assessment will help in understanding the system as a whole, the interaction between various subsystems, and identifying uncertainties and dynamic complexities.

Strong and dependable science-based techniques are needed to produce expertise in the field of resource efficiency and then translate a deeper understanding of the commodity system into action to achieve the aim of a green economy with sustainable consumption and production patterns.