Principles and framework

As stated before, LCA framework is used for products and service by using “cradle-to-grave” -approach. With this, all the energy inputs and outputs are evaluated during the whole life cycle as seen in figure 1. It is also possible to perform simpler gate-to-gate approach, which exclude indirect activities such as supply chain. Due to complex global supply chains in manufacturing industry, which Kongsberg’s propulsion products has as well. Due to this, simpler approach would not be comprehensive enough and would not lead reliable carbon footprint results for products (Jolliet, et al., 2015). The Interna-tional Standards Organization (ISO) have built an LCA standard ISO-14040 -series, which offers solid guidelines for companies to conduct LCA. It is part of the ISO-14000 Environmental Management -series. Below picture only represents example steps of LCA. It is possible to add more critical steps to the life cycle of a product or service.

Figure 1. Cradle-to-grave approach of LCA. Arrows represent transportation The latest LCA framework is built with for iterative phases as follow: Goal and scope definition, Inventory analysis, Impact assessment and interpretation. The first phase of

the analysis is Goal and scope definition (ISO 14040:1997/2006), which is also known as a Goal and system definition. On this phase, the reason and motivation be-hind the LCA conducting is introduced. This part describes how the results are used and who are the audience and stakeholders. In addition to that, the reviewed functional unit is described, and the boundaries of the study will be determined. Functional unit and its boundaries are the two main characteristics of LCA, which is called system function. Some products may have more than one function and therefore primary- and secondary functions need to be identified (Jolliet, et al., 2015). Every functional unit un-der review will have own flow chart called reference flow, which presents all the goods and service to implement the functional unit. In real cases flow chart is basically com-plex product tree where every relation is represented by boxes from the raw material production until disposal or until it exceeds the defined system boundary (Internation Standards Organization, 2018). The first phase is crucial as it sets the boundaries and frame for the whole assessment. The end results are strongly depending on the choices made on this phase (Jolliet, et al., 2015).

Figure 2. Four iterative phases of LCA

The second phase Inventory Analysis or Life-Cycle Inventory (LCI) is quantitative amount mass, energy and pollutants included in the whole reference flow of the re-viewed functional unit. There are several ways to conduct inventory analysis: process-based approach, input-output (I/O) approach, and hybrid model, which is combinations of the first two approaches (Jolliet, et al., 2015).

The fundamental of the phase is to find out the total emissions and resource extrac-tions that are generated throughout the reference flow of the functional unit. Summariz-ing different approaches, we can say that process-based -approach uses physical ref-erence flows and I/O -approach uses economic flows, where each economic sector is

linked to energy consumptions, resource extraction and pollutant emissions per mone-tary unit. I/O approach is many times used for service LCA as it finds better the gaps on supply chain than process-based approach, which tends to consider also unneces-sary sub-processes. On the other hand, I/O approach do not include use -stage and waste treatment, which are key parts of the LCA analysis (Jolliet, et al., 2015). ISO-14044 -standard do not explicitly name different approaches on their guidelines but uses input-output -terms.

It is possible that during the inventory analysis -phase, system boundaries must be re-vised due to a better understanding of the system function. Biggest concerns lie on the data collection when reference flows are complicated and there are numerous func-tional units (Internation Standards Organization, 2018).

Life cycle impact assessment (LCIA) follows the quantities of energy and materials extractions are identified on inventory analysis. Based on the inventory results, emis-sions can be classified in different categories according to their impact to the environ-ment. This phase reveals the possible impact to environment or human health based on the inventory results. The long list gathered from the inventory analysis will be mod-eled to more descriptive manner by addressing emissions to different impact catego-ries. Impact categories can be for example climate change, human toxicity, land- or wa-ter use impacts. Emissions that has similar effects will be in same impact category, which is called midpoint category and it is between the inventory results and damages caused by the certain emission. Midpoint indicator will be pointed for every midpoint category to characterize its contribution (Jolliet, et al., 2015). Character convert the LCI result into common metric such as CO2 eq. on climate change category. The last part of this path is the damage category, which represents the actual damage of the single emission or resource extraction. It is possible to conduct the assessment only to the midpoint category -stage if the results are acceptable compared to the goals of the LCA but continuing until the endpoint (damage category) will yield more intelligible results as shown in figure 3 (Curran, 2015).

Figure 3. Simplified impact assessment process

The last phase Interpretation is a summary of the findings on LCI and LCIA phases. It gives valuable information for the decision makers by highlighting where the environ-mental impacts are generated and what are the possible ways to reduce it. It may show on which life cycle stage the most environmental impact is generated. It is also essen-tial to clearly state how the different allocations and trade-offs are done to gain the pre-sented results as well as the limitations of the study. LCA is an iterative process so in-stead of conducting interpretation only once at the end, it should be considered after every phase of the assessment, especially after inventory analysis before moving to impact categories.