Digital twins (DTs) are one of the latest technology trends in all industries. However, DT development in the architecture, engineering, and construction (AEC) industry is still in its infancy. Digital twins have been proposed as tools that can be applied to several challenges in various areas of the built environment. However, their widespread use is hampered due to the slow pace of digitization of the AEC industry, in addition to the absence of a formalized standard for digital twins’ implementation. We began this study by systematically reviewing publications related to DT applications in the AEC industry in four databases, resulting in 229 publications after applying the proposed criteria. The systematic review highlighted the lack of standardization for DTs in the AEC industry. Additionally, this study assessed the current status of DTs and analyzed the evolution of the concept of DTs in the AEC industry. We also proposed a conceptual framework for DT development for construction assets, using the existing BIM information management standards (i.e., ISO 19650) to promote a better interoperable digitalized built environment.

Southern European countries have milder climatic conditions that differ from their colder northern counterparts, which greatly influence indoor ventilation strategies. The relation between a building’s airtightness and the air change rates remains a topic to be fully tackled in these countries, since natural ventilation is very frequent. In this work, the ventilation and airtightness of a case study were analyzed in-depth to support a discussion on this topic. CO₂ concentration decay and blower-door measurements were used to characterize the infiltration and ventilation conditions of the case study. The case study represents a common Portuguese situation, with highly permeable envelopes, combined with highly variable air change rates. Transient simulations were carried out for the comparison of scenarios where different configurations of possible air paths were analyzed. The simulations included both natural and mechanical ventilation scenarios. An air sweeping effect from bedroom to bathroom only occurred when the mechanical extraction ventilation (MEV) was on. Different air leakage path configurations resulted in substantial offsets, up to 63%, of the air change rate (ACH) due to natural occurring forces. The results confirmed that the relation between airtightness and air change rates should be carefully analyzed in southern European countries, as indoor air quality, comfort of occupants, and energy efficiency are highly influenced by the considered variables.