# End-of-Life Scenarios for Mass Timber: Assumptions, Limitations and Potentials--A Literature Review
## 4 Discussions  
The findings of this review highlight critical implications for the EoL scenarios of mass timber and underline future research directions. Firstly, the emphasis on LCA as a tool to measure environmental impacts leads to the necessity for standardized methodologies that account for time-dependent emissions and align with circular economy principles. Harmonizing LCA frameworks globally is crucial to ensure the comparability of results, particularly for long-lived materials like mass timber. Future research could focus on refining system boundaries and adopting dynamic approaches that integrate time-dependent characterization factors to maximize the precision and comparability of LCA results.  
Secondly, among the EoL scenarios, reuse is theoretically identified as the most sustainable option, yet its adoption faces significant barriers in practice, such as market dynamics, policy inadequacies, and a lack of standardized design practices, as well as the lack of inclusion in LCA calculations. Implementing DfD&R principles could further address these challenges with the integration of LCA calculation, and future research should explore scalable and economically viable strategies for its application in considering the EoL of mass timber, so that more reuse of mass timber could be put into practice.  
Moreover, recycling emerges as a secondary yet essential choice, with the potential to extend material utility and contribute to carbon storage. However, concerns about material degradation and the environmental implications of certain recycling processes require further investigation. Additionally, more research is needed on cascading use to maximize resource efficiency across multiple lifecycles.  
While energy recovery serves as a fallback option, it should be implemented in practice in an optimized way when previous EoL options are no longer possible, with a focus on integrating modern technologies such as CCS. Landfilling, identified as the least desirable EoL scenario, presents complex environmental challenges due to methane emissions and long-term degradation uncertainties. Addressing these issues requires improved landfill management practices and comprehensive long-term studies.  
The cascading use of wood, although a promising concept, faces practical and systemic barriers, including gaps in policies, economic constraints, and public perception challenges. Overcoming these barriers necessitates coordinated efforts among policymakers, industry stakeholders, and academic researchers. New regulations promoting carbon footprint documentation and circular practices in construction projects, as led by Nordic European countries, could serve as a blueprint for other regions.  
Future studies should also address gaps in the EoL of EPDs, particularly in harmonizing methodologies, system boundaries, and verification processes along with the current gaps in LCA. Expanding the scope of EPDs to include dynamic LCA calculations and cascading use scenarios could significantly enhance their utility for decision-making for EPD users in the building sector.  
Therefore, advancing the sustainability of mass timber at its EoL requires an integrated approach that combines technical precision, policy reform, and industry collaboration. By addressing the outlined complexity and research gaps and resolving the gaps from multiple perspectives, the sector can better align with global climate targets and a sustainable future.