## 4 Discussion  
This study aims to analyse the subjective responses of local residents to the luminous environment concerning the activities they carry out in their urban areas. The objective is to establish which aspects of the PLE of urban areas provide their citizens with the feeling that they are associated with sustainable lighting, taking care of the environment, and saving energy. To this end, the KE methodology is used to identify the set of affective impressions of residents on their PLE and examine the relationship with the activities they perform habitually in their urban areas. The findings provide significant contributions from a methodological and practical point of view. From a methodological perspective, the main contribution of this study is the use of SD within the framework of KE to assess residents' emotional responses to the PLE in their urban areas. In the field of PLE, SD is of utmost importance as it helps to analyse user perceptions and their correlation with lighting characteristics. It is widely accepted that different demographic groups hold distinct perceptions of identical products [111; 116]. Through the use of the KE methodology on the basis of SD, the terms applied to identify the relationships between the PLE and the activities performed in urban areas were defined not by experts but by local residents. Using SD in this study provided subjective rating scales adjusted to local residents' languages without expert intervention. This approach ensures that the perceptions of the PLE being assessed are the ones that are valued by the citizens and can be expressed by them. In the present work, SD was employed as the first step of the KE methodology. This approach to product design considers user feedback and translates it into quantifiable metrics that can be used to improve the product's design. By analysing customer perceptions and relating them to objective design elements, it is possible to identify design principles that can successfully enhance the product. In the KE technique, this first phase is essential because it is complicated to determine statistical evidence of relationships between affective responses and overall evaluations of PLE when rating scales are created on attributes that are not understood by local residents or on concepts that present overlapping information. Studies based on subjective evaluations of lighting in public spaces tend to focus on concepts/attributes specified by experts in the field [36]. In this process, respondents may not fully understand the concepts used in the evaluation process, which might provide inaccurate results [117]. Previous research [117] has shown that inexperienced observers' judgments of luminance parameters vary based on whether the terms used in the assessments have been defined beforehand. Moreover, analysing individual semantic profiles offers insight into how citizens perceive a PLE, enabling informed decisions about which axes should be modified by the lighting design. Comparing semantic profiles permits urban and lighting designers to make design changes that align with citizens' expectations and preferences. After this first step of KE, established in this study, where residents' affective dimensions are obtained, further research could establish which design elements of PLE generate them. Statistical models such as neural networks [118], fuzzy logic [119], or linear regression [120] could establish this correlation between specific lighting design elements and semantic attributes. Thus, this correlation could help to incorporate the preferences and needs of citizens into lighting design specifications to ensure the final product meets their requirements. Additionally, it would also be useful to explore the affective responsesof lighting designers, architects, and urban planners. This would help identify any differences in perception between them and the citizens.