## 6 Conclusions and Future Directions  
Considering the construction safety issues and trends in the construction sector, a framework for an extended reality solution for holistic safety management in construction has been proposed. It responds to the trend of using extended reality in the AECO sector and seeks to fill the unresolved gaps associated with standardisation in the development of XR experiences for safety, the entire project life cycle and the integration of the different uses and factors that affect safety. Thus, the framework considers a holistic vision of construction safety management considering best practices in safety management; an approach from Construction 4.0 and methodological trends in the sector, incorporating BIM and Lean Construction, with Construction 4.0 technologies; and extended reality as a paradigm of human-machine interactions in new contexts in virtual work environments. In direct response to the research objectives, the proposed framework integrates a holistic and lifecycle-based approach to safety management, supported by BIM, Lean Construction, and PtD principles, and is deployed within extended reality environments. It operationalizes this vision through a modular and adaptable structure that allows the integration of safety-related data, models, and XR tools across different project stages. The implementation examples illustrate how XR environments can be used not only for training, but also for planning, inspection, real-time decision-making, and monitoring. These contributions move beyond isolated applications, offering a replicable and scalable methodology that supports both current needs and future developments in Construction 4.0. The proposal incorporates a broad view of the project life cycle from a safety perspective. The inclusion of safety aspects from the beginning of the project (Prevention through Design) is facilitated by XR environments and the incorporation of BIM. The integration of BIM environments to XR developments allows synchronization with project management, aligned to Lean planning best practices. In this way, XR environments are no longer considered static models or generic construction simulations but are transformed into updated platforms for specific projects. Safety management is performed according to the progress and particularities of each project, incorporating the necessary variables to replicate all conditions and expanding the management potential beyond what reality allows. This proposal allows professionals in charge of construction safety to learn how to integrate XR tools into their traditional workflows and migrate to these new environments according to their needs and work stages, always with an eye on the broad vision of safety management throughout the entire life cycle. In this way, the explicit link to the trends of Construction 4.0 also shows the integration sought in the technological and methodological deployment. Therefore, this is not an isolated proposal, but one fully integrated into the way the sector is working and will work in the coming decades. The efforts to deploy XR are aligned to the current and future trends of working in virtual environments. The future development of a 'Construction metaverse' will require the integration of various tools, and skilled professionals and good management practices will be equally important in these new work environments. Although the framework proposal and developments shown do not directly consider virtual work environments (such as the metaverse or NVIDIA Omniverse, for example), they represent an effort to adapt the sector to these new trends. A relevant aspect of the framework is its capacity to adapt to different project types, scales, and regulatory contexts. Its modular design and flexible integration of data flows allow it to be customised for small, medium, or large projects, and to align with varying degrees of digital maturity. Moreover, its structure facilitates compliance with local or international safety regulations, offering a foundation for future standardisation.