Principles for the application of life cycle sustainability assessment

This paper aims to establish principles for the increased application and use of life cycle sustainability assessment (LCSA). Sustainable development (SD) encompassing resilient economies and social stability of the global system is growingly important for decision-makers from business and governments. The “17 SDGs” emerge as a high-level shared blueprint for peace, abundance, and prosperity for people and the planet, and “sustainability” for supporting improvements of products and organizations. A “sustainability” interpretation—successful in aligning stakeholders’ understanding—subdivides the impacts according to a triple bottom line or three pillars: economic, social, and environmental impacts. These context and urgent needs inspired the LCSA framework. This entails a sustainability assessment of products and organizations in accordance with the three pillars, while adopting a life cycle perspective. The Life Cycle Initiative promotes since 2011 a pragmatic LCSA framework based on the three techniques: LCSA = environmental life cycle assessment (LCA) + life cycle costing (LCC) + social life cycle assessment (S-LCA). This is the focus of the paper, while acknowledging previous developments. Identified and reviewed literature shows challenges of addressing the three pillars in the LCSA framework implementation like considering only two pillars; not being fully aligned with ISO 14040; lacking interconnectedness among the three pillars; not having clear criteria for results’ weighting nor clear results’ interpretation; and not following cause-effect chains and mechanisms leading to an endpoint. Agreement building among LCSA experts and reviewing processes strengthened the consensus on this paper. Broad support and outreach are ensured by publishing this as position paper. For harmonizing practical LCSA applications, easing interpretation, and increasing usefulness, consensed ten LCSA principles (10P) are established: understanding the areas of protection, alignment with ISO 14040, completeness, stakeholders’ and product utility considerations, materiality of system boundaries, transparency, consistency, explicit trade-offs’ communication, and caution when compensating impacts. Examples were provided based on a fictional plastic water bottle In spite of increasing needs for and interest in SD and sustainability supporting tools, LCSA is at an early application stage of application. The 10P aim to promote more and better LCSA applications by ensuring alignment with ISO 14040, completeness and clear interpretation of integrated results, among others. For consolidating its use, however, more consensus-building is needed (e.g., on value-laden ethical aspects of LCSA, interdependencies and interconnectedness among the three dimensions, and harmonization and integration of the three techniques) and technical and policy recommendations for application.

be considered (Zanghelini et al. 2018). Sustainable development requires decision-makers to think beyond current economic structures and indicators, such as the gross domestic product (GDP), inducing resilient economies that monitor the well-being of countries without neglecting the social stability of the global system (Hoekstra 2019). This implies re-thinking economies based on inclusive and more sustainable pathways.
The 2030 Agenda for Sustainable Development (UN General Assembly 2015) provides a shared blueprint for peace, abundance, and prosperity for people and the planet. At its heart are the 17 Sustainable Development Goals (SDGs), which are an urgent call for action by all countries-developed and developing-in a global partnership (UN Department of Economic and Social Affairs 2015).
For sustainable development to be implemented effectively, performance measures are required. Sustainability is understood differently by different stakeholders and decision-makers. This complicates coordinated measurement, mapping, and improvement of products' and organizations' sustainability performance along their value chains and across regions (Arroyo et al. 2016;Valdivia et al. 2013;Zamagni 2012).
The Agenda 21 (UN 1992) built upon the Brundtland Report (1987) made an important contribution to the global discussion on sustainable development by emphasizing the problems of the north-south development divide and the need to link social and economic development with environmental protection. Without a clear point of origin, one of the more ubiquitous interpretations of sustainability subdivides the impacts according to three pillars: economic, social, and environmental impacts (Purvis et al. 2019). This was translated into the triple bottom line (TBL) by Elkington in 1999, whom later

Purpose of this position paper
The aim of this position paper is to establish principles for the application and use of life cycle sustainability assessment (LCSA) by building on the best practice currently available. Furthermore, the purpose of this paper is to promote LCSA thinking worldwide.

Life cycle sustainability assessment
The context and urgent needs described have inspired the concept of the LCSA framework. This entails a sustainability assessment of products and organizations, originally coined in accordance with the three pillars (Kloepffer 2008), while adopting a life cycle perspective. The life cycle perspective spans from the extraction of resources, material production, manufacturing, logistics, use, maintenance, repairing, recovery of resources, and re-manufacturing, until the final disposal of waste. The advantage of LCSA is its system perspective and the identification of potential trade-offs between the three pillars.
Since 2011, the Life Cycle Initiative promotes a pragmatic LCSA framework (UNEP 2011), which was taken up by the community in the form of studies and papers of a diverse geographical and sectoral origin. Techniques to address each of the three pillars in the LCSA framework correspond to the environmental life cycle assessment (LCA) (built on ISO 14040: 2006;ISO 14044: 2006), life cycle costing (LCC) (SETAC 2011), and social life cycle assessment (S-LCA) (UNEP 2009(UNEP , 2020. While we acknowledge the developments in the past years, this position paper focuses on this pragmatic LCSA framework endorsed and promoted by the Life Cycle Initiative (Finkbeiner et al. 2010;Kloepffer 2008;UNEP 2011;Valdivia et al. 2013), for product-, service-, and organization-related applications. With this focus, we define LCSA as follows: The above formulation represents an operational approach in which the three methods are executed separately to the same case, and then, their outcomes are compared or aggregated using weighting. A recollection of developments within the past 12 years include many different conceptualizations of LCSA (Guinée 2015;Guinée et al. 2011;Heijungs et al. 2010;Neugebauer et al. 2015;Schaubroeck and Rugani 2017;Zamagni 2012 andZamagni et al. 2013). Recently, another extension of LCSA has been developed by Weidema et al. (2020) to cover the indicators and targets of the UN Sustainable Development Goals.
The pragmatic LCSA framework, on which we focus, is especially dependent on the three separate methods, which have different levels of data availability and maturity (related to tools user-friendliness, methodological issues about the impact assessment phase, interpretation of results, reports' records availability); see Fig. 1 for a qualitative assessment). Nevertheless, the LCSA framework is globally accepted and the need for an applicable approach is constantly increasing (Traverso et al. 2012a, b).

LCSA application: challenges
Addressing the three pillars in harmonizing the LCSA framework implementation is not a trivial task, additionally leading to interpretation problems (Chen and Holden 2018;Traverso et al. 2012).
LCSA reports assessed (a sample of 165 LCSA papers were identified and analyzed, Leroy-Parmentier et al. 2021) show a diversity in the applications and challenges. For example, they may: a consider only two pillars; b base on approaches not fully aligned with the ISO 14040 framework; c lack interconnectedness among three pillars; d apply contradicting models and assumptions such as inconsistent system boundaries, 1 preventing fair comparisons; e not clearly explain and communicate assumptions and data chosen; f not follow clear criteria for the definition of the functional unit and system boundaries, and for the selection of indicators; g not follow cause-effect chains and mechanisms leading to an endpoint; h not clearly define the target audiences and users of the LCSA results and disregard their goals, personal values, or cultural differences; i present results with different levels of detail and background information for each pillar which make them hard to communicate and more difficult to understand especially for decision-makers who need them the most; j apply arguable and non-transparent weighting of results linked to LCA, LCC, and S-LCA.
Thus, additional guidance is needed for harmonizing practical applications of LCSA, ease the interpretation, and increase the usefulness also for non-experts and decisionmakers at policy, business, and citizens level globally.
Agreement building among LCSA experts and reviewing processes were established and implemented to strengthen the consensus on the topics addressed in this paper. It is expected that broad support and outreach will be ensured by publishing this as position paper of the Life Cycle Initiative.

Principles for conducting an LCSA study
To fill the gap for better-informed decision-making, and following the current state of the art, the following ten (10) principles are presented.
Note: Examples added for illustrating several principles are based on a fictional plastic water bottle.
1. Understanding of the areas of protection and impact pathways including the cause-effect mechanisms connecting inventory results to mid-and endpoints of an area of protection (AoP

Consideration of the product utility beyond the func-
tional unit (co-benefits) 3 . This principle ensures a proper understanding of the product concerned through the definition of its core characteristics. Example: A water bottling facility located in a poor area can have the co-benefit of making clean, piped water cheaply available for the local community that have hitherto not had piped water supply. 6. Materiality of the system boundaries 4 ensures that relevant and significant unit processes that have impacts on one or more pillars of sustainability are within the system boundaries and are not excluded from the assessment.
Example: For the example of the plastic water bottle, the system boundaries reach from the plastics granulates to the bottles recycling phase. From the social and environmental perspectives, waste plastic collection is important and from the economic perspective, the administrative offices of the facility. 7. Consistency ensures the non-contradictory use or selection of system boundaries, methods, impact categories, models, data, and assumptions to allow for meaningful comparisons of the datasets produced over time.

Outlook for more LCSA application
To advance the application and research of LCSA, the following aspects need further attention: Expand and improve the application of LCSA by taking into consideration the above principles. This will create more and better LCSA applications. Identify relevant other approaches for LCSA applications, such as the "6 capitals" framework which covers the following capital areas and is emergingly used for integrated reporting: "financial," "manufactured," "intellectual," "natural," "human," and "social" (Capitals Coalition 2016).
Consensus-building and dialogue on value-laden ethical aspects of LCSA, its goal, and the interdependencies and interconnectedness among the three dimensions. Throughout this process, interdisciplinary collaboration and involvement of key stakeholders contributing to LCSA globally will facilitate the engagement of potential decision-makers. The harmonization and/or integration of the three individual assessments (LCA, LCC, and S-LCA) within LCSA. This comes timely with the S-LCA guidelines (2020) that complements the LCA and LCC experiences. Where cause-effect chains and mechanisms for implementing an LCSA are insufficient or unknown, method developers are called to contribute with their development or enhancement. Additional technical and policy recommendations to conduct LCSA, for enhanced rigor and reproducibility of results.
We hope that the above principles and areas of attention can increase the pace and scale of LCSA development and implementation in the different regions, sectors, and products around the world in support of the Sustainable Development Goals and sustainability assessments.
Funding Open Access funding enabled and organized by Projekt DEAL.
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