# Seeking a Definition of Digital Twins for Construction and Infrastructure Management
## 5 Defining and Standarising the Concept of a Digital Twin for the Built Environment
### Creation of a European Standardisation WG for Digital Twins
The final draft was sent for ballot within CEN/TC 442 in March 2024 and approved in June. CEN/TR 18077 was published in September 2024 [14]. CEN/TR 18077 structures the information in four categories: main use, secondary use, asset type, and phase of the life cycle in which the DT is implemented. The predominant use cases primarily facilitate the operation of the constructed asset, with optimisation and maintenance of operations representing the primary applications. Design optimisation, safety measures, and training are included only as secondary use cases. A special typology, \"test lab\", was created to group DIs used to enhance products and services developed in real laboratories. The miscellaneous category of \"other uses\" includes irrigations, occupants' wellbeing, or the analysis of climate change resilience. D'2 EPC [57] is a EU funded project which fed other research project, Chronicle, with relevant data regarding digital twins applied to the energy performance of buildings. D'2 EPC presented a pilot building in Thessaloniki (Greece) used as both a residential and an office, as well as a University building in Nicosia (Cyprus). The experience with these pilots were used both in CEN/TC 442/WG 9 for the definition of digital twins and in CEN/TC 371/WG 5 for the development of a methodology for operational energy performance of buildings. Digital twins for other purposes, not conceived as \"built environment\", were analysed in ISO/IEC TR 30172:2023 [58]. Once the draft was agreed in WG 9 and sent to CEN/TC 442 for ballot, the EN standard for concepts and definitions of DTs in the built environment was proposed. It will consider the recently published \"horizontal\" standard ISO/IEC 30173:2023 [45]. The ballot was launched in February 2024 and approved in April 2024. The draft should be ready for the CEN Enquiry ballot before the end of 2024 and, if approved, should be published in 2025. This European standard will harmonise the definitions applicable to DTs, providing a common solid ground for practitioners and researchers, helping the procurement process and other related activities. This standard aim is to provide the information management framework for DTs in the built environment, enabling an ecosystem of connected digital twins. This would release even greater value, using data to support a more efficient design, construction, operation, and end-of-life processes for buildings and infrastructures. The absence of standardised definitions for the qualitative specification of a digital twin p1 ses a significant challenge in differentiating this concept from BIM or in categorising the DTs based on their intended use and the technology applied. This lack of definitions endangers the application of digital twins in public or private procurement. To address this issue, it is imperative to have reliable definitions in international standards, thereby fostering a shared understanding of the underlying concepts. The European standard developed in CEN/TC 442 should ensure transparency, efficiency, and high-quality outcomes in the DT field. It should foster collaboration and innovation in the construction industry, in particular:  
1. Improving communication and collaboration: shared language among stakeholders (researchers, architects, engineers, contractors, suppliers, surveillance authorities, etc.). 2. Enhancing data interoperability across various software platforms: seamless exchange and integration of data, preventing errors and inefficiencies caused by incompatible formats or interpretations. 3. Providing criteria for consistency checks and quality control, including auditing and monitoring compliance with legal requirements or the client's brief. 4. Fostering innovation, as clear and shared definitions will reduce barriers to entry for new firms by setting transparent expectations and consistent benchmarks.