## 2 Materials and Methods  
The research is based on a comprehensive assessment of the state of the art described in Section 3. The analysis of the current situation is based on the following sources of information:  
1. Analysis of the current version of IFC, of the main EPD standards (EN 15804, ISO 21930 and ISO 22057), and the ongoing developments related to the digitalization of construction product information in the BIM standardization committees (ISO/TC 59/SC 13 and CEN/TC 442). In particular, the European project WI 0442061 defining the digital declaration of performance and conformity of construction products [11] was considered. A sample of dEPDs from programme operators (POs), available in the ILCD + EPD format in the ECO Platform portal [12], was analyzed for discrepancies with the IFC elements. The EPDs were selected to represent a range of POs and product families, and the availability in English was a requirement. Each indicator in the EPD was analyzed to determine its correspondence (or lack thereof) with an existing IFC element. 2. Gaps related to the integration of LCA data in other formats (e.g., ISO 22057 or ILCD + EPD) identified in [9; 12]. The conclusions of these studies were assessed and summarized to evaluate its applicability to the IFC schema, testing the assumptions with the use case (the BIM model described in Section 4.3). 3. Gaps related to the integration of LCA data in BIM identified in previous research not identified in [9; 12]. It was based on a search in major journals with combinations of the keywords BIM, EPD, EN 15804, ISO 21930, life cycle assessment, LCA, IFC, ISO 22057, DPP, digital product passport, construction products, buildings, and built assets. As the research conducted in [9; 12] was recent, few additional limitations were found in these queries. The research also considered the practical experience of the authors in the fields of LCA, EPD development and verification, modelling of buildings for sustainability assessment purposes, policies related to construction products and scientific research. This experience was very valuable to identify limitations and bottlenecks in the process of transferring LCA-based data into BIM. The gaps identified during the research were analyzed considering the environmental parameters defined in the core EPD standards (EN 15804 and ISO 21930), EPDs published by POs, the international standards defining requirements for data templates, and the DPP for construction products defined in the Regulation (EU) 2024/3110 on construction products (new CPR) [13]. The research assigned each EPD parameter (impact category or indicator) to an IFC element, when possible, and identified the gaps (e.g., information which cannot be stored in IFC 4.3). For some of the identified limitations, a tentative solution or action is defined. The analysis is described in Section 4 and summarized in the conclusions. Adding customized properties is a widely used strategy, useful for projects within the same organization or groups of organizations. However, it limits the interpretation in different software tools or across systems. Therefore, this paper proposes a common and globally standardized structure for LCA-based product data. The preliminary solutions were tested in the digital model of one of the five pilots [14] from an EU-funded research project, CHRONICLE (see Section 4.3). CHRONICLE develops digital tools to improve building performance by monitoring energy consumption, comfort, and assisting with renovation and maintenance planning. These tools will help establish good building practices by considering environmental, social, technical, and financial aspects. The selection criteria for the pilot were the maturity of the BIM model (as IFC), the availability of EPD data of its constituent materials, and the replication potential. The selected building is a former commercial building located in Zaragoza (Spain) that has been refurbished and repurposed as a social housing block. It has a building typology very common in Spain, including the heating systems.