Retos actuales

The approach for the decision context described above is outlined in this sec-tion.

Criteria identification A questionnaire based survey was created and sent to a variety of stakeholders with the goal of identifying relevant criteria to help in the selection of appropriate sustainable materials to be implemented in ship struc-tures. The project partners were asked to suggest criteria that they considered as relevant. In doing so they should consider multiple aspects, such as

• Technical (e.g. material properties),

• Economic (e.g. costs, financial benefits),

• Environmental (e.g. emissions, pollution),

• Logistical (e.g. supply chain, availability),

• Regulatory aspects,

• Others.

Some visual supports were provided to trigger the though-process, as depicted in Figure 4.4. The aspects related to raw materials, manufacturing and installation were later combined in the ‘initial stage’.

Figure 4.4: Pictures to trigger ideas for the criteria identification

Moreover, they were asked to think about the whole life cycle, as depicted in Figure 4.5:

Figure 4.5: The ship life cycle to trigger ideas for the criteria identification

Some examples were given, but otherwise no criteria were prescribed (to avoid any bias) and every participant was asked to fill in their own suggestions and indicate whether this was applicable to HSLA, composites or both, covering all application cases. Alongside they were asked to provide an initial judgement about importance and data availability.

In this way the approach taken was a hybrid between a bottom-up and a top-down approach: Whilst the fundamental objectives (minimisation of LCC, Risk Assessment (RA) and Environmental Impacts (EI) were provided top-down (i.e.

identified early in the process and provided as requirement for the overall eval-uation), the individual case study specific criteria were determined bottom-up (identified by the stakeholders). This approach was taken in order to ensure that the fundamental objectives were met, without overlooking the specific techni-cal details that are important to the stakeholders and accordingly influence the decision process. The full survey is attached in Appendix A.1.

The suggested criteria were collected and mapped to understand inter-dependencies and how they relate to each other and the objectives. The extensive list of sug-gested criteria is presented in Appendix A.2. They were condensed down to a level which can be seen as providing an optimum level of detail: not too de-tailed so as to be unfeasible but dede-tailed enough to capture the complexity of the problem and be beneficial to the end-user. This was in accordance with the requirements of criteria to be complete, operational, non-redundant and minimal (see Section 3.1.2). These criteria were called the Performance Indicators (PIs).

Subsequently, a set of environmental and risk related Key Performance Indicators (KPIs) was established, which related the identified Performance Indicators (PIs) to the fundamental objectives.

Data collection and evaluation Data was collected through interviews and questionnaires with stakeholders and experts that were addressed specifically at the individual areas of expertise. Personal follow-up was done to capture some of the nuances involved in the responses. Surveys and interviews were carried out with the following experts, which together provided a high level of breadth and depth that was judged as very valuable for the process.

• 3 people from ship yard (2 × technical, 1 × sales and economic experts)

• 6 material experts (3 × HSLA, 3 × composites)

• 2 people from technology provider (ship design)

• 1 person from classification body

Moreover, secondary data sources were used, such as available literature on HSLA and composites as well as literature on LCC and management of ship struc-tures.

Literature and expert data were compared to evaluate the reliability and consis-tency of the different data sources. The stakeholders are experts in their respec-tive fields, however there are some uncertainties with regard to the new materials.

The confidence in data was therefore evaluated alongside the data collection. The data collection and evaluation is presented in detail in Section 4.2.

Life Cycle Cost and Performance Assessment (LCPA) The LCPA was carried out as described in Section 3.3. The different alternatives were evaluated with regard to their sustainability performance, compared to the baseline of con-ventional steel. The analysis was split between costs, environmental impacts and risk. For each of them the different life cycle stages were considered, broadly categorised as Initial (I), Operation and Maintenance (O&M) and End of Life (EoL) stage, as depicted in Figure 4.5.

The LCC was done on a quantitative basis. An initial LCC model for a ship was developed based on literature values from Burman et al. (2006). The calculations and values were adjusted, feeding in the MOSAIC findings. Additionally, further estimates were requested from MOSAIC participants, especially from the shipyard and design experts.

The life cycle risks and environmental impacts on the other hand were assessed in a semi-quantitative way, by evaluating relevant KPIs identified through the stakeholder survey. Since some of the suggested PIs (such as material properties etc.) impact on some of the others (especially the ones related to costs, envi-ronmental impacts and risk), the evaluation was split between Performance and Significance. The former provides a measure of how much better or worse the alternatives perform on a specific aspect in comparison to the baseline, whilst the latter defines how important these changes are with regard to the fundamental objectives. Further details are provided in Section 4.3.

Sensitivity and uncertainty analysis The data collected in the LCPA was analysed with regard to the sensitivity of the results towards individual factors and the uncertainty attached to those that contribute most to the results. This was done separately for LCC, EI and RA, looking at the sensitivities first and refining the most sensitive factors for the uncertainty analysis, as explained in detail in Section 4.4.

MCDA The cost, environmental and risk data from the LCPA was integrated by using the MCDA framework proposed in Section 3.5. Details and results are presented in Section 4.5. Figure 4.6 depicts how the framework introduced in Figure 3.2 is applied to the case study. Based on the guidance by Rowley et al.

(2012), a Multi-Attribute Utility Theory (MAUT) approach was chosen for the evaluation. The full results, including the consideration of the outcomes of the sensitivity and uncertainty analysis, as well as a parametric investigation of the influence of the weighting factors, are discussed in Section 4.5.

Figure 4.6: MCDA approach (diagram adapted from Linkov & Seager 2011)

4.2 Data Collection and Evaluation

In this section, the details of the data collection and evaluation are presented for the MOSAIC case study, covering the key aspects discussed in Section 3.2.

Section 4.2.1 provides an overview of how suitable PIs were determined from the stakeholder survey. The subsequent sections present the data collected for HSLA (Section 4.2.2) and composite material (Section 4.2.3).