## 5 Future Research Perspectives  
There are several aspects that need to be covered in future research activities addressing the role of existing buildings. * Even if improving the energy efficiency performance of historic/heritage buildings is challenging, a thorough assessment is needed. Setting ambitious refurbishment targets to fulfil the current energy performance regulation as minimum ambitions, focusing on achieving zero emissions or plus house by incorporating energy efficiency and renewable energy measures, is important. The uncertainties of future energy mixes and user behavior should also be taken into consideration. Further studies should perform scenario analyses to evaluate different realistic refurbishment measures addressing the uncertainties in background data, assumptions, and methodological choices. Creating awareness and developing expertise to fill in the knowledge gap in this area are also needed. * A life cycle assessment should be used as a decision support tool to assess the sustainability of refurbishment measures, assess the performance before and after refurbishment, and make informed decisions regarding refurbishment vs. demolition and new building scenarios. Further studies should consider performing detailed and transparent LCA of existing buildings, including both refurbishment and adaptive reuse of existing buildings with historic/heritage values. The study should provide a clear description of the ambitions (for, e.g., achieving TEK 17, ZEB, passive house, plus house) and scope of the study (for, e.g., level of refurbishment, LCA system boundaries following EN 15978 or NS 3720, building physical boundaries in accordance with NS 3451) including the whole life cycle of the building (modules A1-D). Cultural heritage values and different environmental indicators than GHG emissions should also be considered in the analysis. * Implementing refurbishment and adaptive reuse measures to achieve reduced emission values can be difficult without affecting the heritage values. This calls for a system that systematically considers the role of cultural heritage, and the development of refurbishment and adaptive reuse measures that attend to the socio-cultural values. Further, such systematic evaluation and measures for attending to socio-cultural values should be incorporated into methods such as BREEAM and equivalent systems. * This study was conducted based on the results of only a few LCA studies on existing buildings with historic/heritage values. It is challenging to conduct a comparative assessment of LCA studies of refurbishment projects due to different refurbishment measures, background data, and methodological choices considered in the LCA calculation. Collecting best practices will enable gathering lessons learned from the technical, environmental, and historic/heritage performance of existing buildings. Futurebuilt is a good example where basic information and the LCA results of the pilot projects are reported in a standardized format. Collection of those documents from Futurebuilt pilots and case studies from BREEAM NOR for BREEAM-certified buildings in a type of database or renovation passport can be a way forward for collecting best practices for rehabilitation and adaptive reuse of existing buildingswith historic/heritage values. This can also support incorporating refurbishment and adaptive reuse projects in the on-going work on setting national GHG emission requirements and reference or benchmark values in Norwegian building codes (TEK) [62]. * The scope of the current LCA studies is limited to environmental impact assessment. Further studies should consider incorporating the economic, social, and historic/heritage aspects to widen the scope of LCA and provide a more holistic view. It is important to include other indicators such as resource depletion and toxicity to avoid problem shifting from one indicator to another. In addition, incorporating the dynamic LCA approach will provide a better understanding of time aspects of refurbishment and adaptive reuse.