## 4 Discussion and Conclusions  
This study analyzed the role of green building certifications and material selection criteria in facilitating the transition toward PEDs. Through a document review and the examination of three Italian case studies--particularly residential retrofitting projects in Bolzano and Florence--key technical solutions were identified to meet PED objectives: energy efficiency, renewable energy production, and energy flexibility. The findings enabled a comparison of the construction characteristics of the adopted technological solutions with the criteria outlined in green certification systems, highlighting the relevance of voluntary protocols in supporting the environmental sustainability goals of PEDs. Adopting criteria based on specific indicators proposed by these protocols was found to significantly reduce the environmental impact of building interventions, particularly through passive energy efficiency solutions. The Bolzano case, for example, illustrates how certifications like KlimaHaus can align with Italian regulatory frameworks, particularly the Minimum Environmental Criteria (CAM), enhancing transparency and traceability in material selection. This alignment strengthens the social and institutional credibility of PED-related interventions while supporting broader sustainability goals. Green building certifications have evolved from simple acknowledgments to powerful tools for incentivizing sustainability. They raise awareness, influence design decisions, offer economic benefits, and foster energy performance monitoring. Furthermore, future PED-specific certification systems could integrate dedicated material selection criteria to promote greater sustainability. This study underlines the importance of adopting GBRS-based material selection criteria as a promising practice for ensuring sustainable and efficient interventions in energy retrofitting projects. Despite these contributions, the study presents certain limitations. The analysis relied exclusively on documentary sources available in Italian, as the data primarily originated from local administrations and planners involved in PED projects. Additionally, the number of case studies was limited, reflecting only a partial view of the diverse international experiences related to PED transitions. Lastly, the study focused on insulating materials, leaving room for further exploration of other building components. Nevertheless, this research revealed several key insights. To facilitate the transition toward PEDs, it is advisable for building interventions to follow GBRS criteria in material selection. Certification protocols can play a significant role in energy retrofitting projects by increasing the likelihood of employing sustainable materials. Future PED-specific certification systems should integrate criteria dedicated to material selection, further enhancing sustainability in such projects. In conclusion, this study contributes to the scientific debate on PED transitions by offering a methodological framework that, with appropriate adjustments, could be extended to international contexts. Future research could expand the focus to include other building components, conduct comparative analyses with international examples, and refine material sustainability indicators for inclusion in future PED-specific certifications. **Author Contributions:** Conceptualization, T.F. and P.C.M. ; methodology, T.F., P.C.M., and T.V. ; validation, T.V. ; formal analysis, T.F., P.C.M., and T.V. ; investigation, F.R. ; resources, P.C.M. and F.R. ; data curation, T.V. and F.R. ; writing--original draft preparation, T.F., P.C.M., T.V., and F.R. ; writing--T.F. ; visualization, F.R. ; supervision, T.V. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by RdS 2022-2024, WP1, LA 1.33. This research was funded by Agreement between the Ministry of Environment and Energy Security and ENEA. Three-Year Implementation Plan 2022-2024.