## 3 Methodology
### Research Methods and Survey Techniques  
#### 3.2.1 Delphi Method  
The Delphi method, developed by the RAND Corporation (Santa Monica, CA, USA), in 1953, is a forecasting technique based on expert opinions [33]. This method utilizes iterative rounds of anonymous surveys to deepen the understanding of uncertain issues through achieving a consensus among experts. The Delphi method particularly emphasizes a feedback mechanism, allowing experts to adjust their views after considering the opinions of their peers, thereby enhancing the accuracy of judgments and facilitating the formation of consensus. It is widely applied in exploratory, normative, and predictive analyses [34]. Typically, this process involves the careful selection of anonymous experts to form a chosen group who undergo two to three rounds of structured surveys. After each round, the questionnaire is adjusted based on expert feedback and distributed for the next round, with this process repeated until a consensus is reached among the experts [35; 36; 37].  
Considering the scientific validity and quality control of the questionnaire, the content of this study's questionnaire references the one developed by [PERSON] and [PERSON] [38]. The questionnaire includes (1) basic information about the experts, as shown in Table 1; (2) descriptions of the indicators: each indicator's corresponding meaning and the supplementary explanations revised by the experts; (3) a 5-point Likert scale is used for rating the indicators. To ensure the rigorous use of the evaluation tool, other Delphi questionnaire ratios toels were also investigated. According to the study by [PERSON], [PERSON], [PERSON], [PERSON], et al., using different rating scales in Delphi surveys does appear to affect the results; however, the 5-point scale was found to be most consistent with the final outcomes [39]. Furthermore, a literature review on the Delphi method revealed that previous researchers have commonly employed the 5-point Likert scale [40; 41; 42]. Therefore, this study also adopts the 5-point Likert scale for the questionnaire; (4) the survey also assesses the experts' familiarity with the guidelines and judgment criteria.  
Scientific Validity of the Experts  
To ensure the authority, representativeness, and reliability of the research results, this study follows the criteria outlined by [PERSON], [PERSON] et al. [43], which suggest that experts should meet four requirements: (1) acquire knowledge and experience through investigation, (2) participate voluntarily, (3) have sufficient time to participate, and (4) possess effective communication skills [43]. Therefore, this study adopted the following criteria for including experts: 15 experts with over 8 years of experience in design-related work or research, 2 experts with more than 5 years of experience in environmental science, and 3 software engineers with over 5 years of work experience, for a total of 20 experts. All the experts participated voluntarily, and they had sufficient time to engage in the study.  
Questionnaire Distribution  
In this study, a questionnaire was developed based on the collected usability metrics, and a Delphi survey was conducted from 5 March 2024 to 12 March 2024. The questionnaire was distributed via email. In the first round of the Delphi survey, statistical feedback information was collected from the questionnaires, and we removed some indicators based on the experts' suggestions. The first round of revisions was incorporated into the second round of the consultation questionnaire, where experts then rated the revised indicators. Experts were required to rate each item using a 5-point Likert scale, with 1 being \"very unimportant\", 3 being \"neutral\", and 5 being \"very important\". Throughout the survey process, experts were also encouraged to propose new measurement indicators to ensure a comprehensive evaluation.