## 2 Materials and Methods
### The Design and Structure of the SCABIM Model  
In order to design and structure the SCABIM model, it is essential that the agents involved in the building condition assessment process (maintenance technician and the BIM team) interact using a cooperative and collaborative methodology by means of their own server via VPN and real-time synchronisation platforms in the cloud.  
Before beginning to prepare the BIM model of the building's state of conservation, a contract document was drawn up, including the BEP (BIM execution plan) [41; 42], which sets out general information about the building, the roles and responsibilities of the BIM work team; the goals and uses of the BIM; the LOD (level of development) [43; 44] of each model and the nomenclature of generated files; and the strategies for document control and organisation of the models along with the resources.  
A thorough examination of a building requires a graphic survey prior to its current state, endowed with a sufficient degree of accuracy to precisely determine the geometric configuration of the structure as well as the particular changes that users have gradually introduced over time [45]. At present, the combined use of digital techniques for geometric data collection by means of a topographic survey with total station, terrestrial laser scanner and short-range photogrammetry assisted by RPAS (remotely piloted aircraft system) is the most effective procedure for conducting a high-precision geo-referenced architectural survey. Total station control points can be determined for geo-referencing and metric verification of data. The terrestrial laser scanner can capture geometric data at a long distance with very high accuracy. Short-range photogrammetry assisted by RPAS facilitates the capture of data in areas that are hidden or hard to access beyond the reach of a laser scanner. The architectural survey accomplished using these techniques is thus a three-dimensional digital twin of the captured data [46].  
Information should be classified in several federated models. Taking into account the aspects that are analysed in the state of conservation assessment, four models are generated: the Datum model to link the general information and the collected previous information about the building, the architectural model, the structural model and the MEP model. This set of models is exportable in an open source file (IFC; Industry Foundation Classes) to perform the quality control of these models. The revised model set is prepared to insert the building conservation status parameters defined in the ITE. These parameters allow the addition of damage and alteration data (input) to the model or set of models through a family designed for this purpose. Once the model has been fed with this data, view templates, filters and planning tables are generated to extract the information on the state of conservation of the building (output) in a visual and agile way. This SCABIM model is a dynamic model as it allows both input and output of information regarding the state of conservation of the building during the rest of the building's life cycle. The proposal's process is depicted in Figure 2.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**State of Conservation** & **Severity of Damage** & **Assessment of Intervention** \\ \hline Apparently good & No apparent risk & Immediate (\textless{}24 h) \\ Constructive deterioration and deficiencies & Risk to other construction elements & Very urgent (\textless{}3 months) \\ Cannot be determined & Risk of progressive deterioration & Urgent (\textless{}12 months) \\ Specific deficiencies & Risk to third parties & Necessary in medium term \\ Extreme deterioration & & Maintenance \\ \hline \hline \end{tabular}
\end{table}
Table 1: Pre-set parameters in the protocol for conducting the technical inspection of a building.