# An Ontology-Based Representation of Valued System for HBIM
## 1 Introduction  
In the last decade, the advent of digital modelling tools and in particular the rise of the building information model (BIM) paradigm, changed completely the approach of representing ad managing the so called \"built cultural heritage\". Indeed, by adopting the BIM concept to historical building information modelling (HBIM) it is possible to correlates 3D models--describing the geometry of heritage architectural objects and their elements (i.e., walls, covering systems, vaults, decorations)--with different pieces of information (materials, construction techniques, physical properties, decay, etc.). Several works in literature are proving the effectiveness of HBIM as a new paradigm for managing restoration works, maintenance works and management of historical buildings [1; 2; 3; 4; 5; 6]. BIM can represent a powerful tool to boost digital economy, for example in Europe the 'Directive on Public Procurement' (EUPPD 24/2014) asked the 28 EU countries to adopt 'building informative modelling' by February 2016 in order to support the whole LCM (life cycle management). However, several authors [7; 8; 9] have highlighted bottlenecks to an effective adoption of BIM, and even more of HBIM, in current practice. [PERSON] et al. [10] underline that to increase the HBIM adoption it isnecessary to undertake different actions devoted to tackle two of the main issues: improve the time-cost effectiveness and diminishing the technical gaps nowadays present in the HBIM workflow. As highlighted by different author main requirements to fully adopt BIM for historical architecture are: (i) the quality of the model and its reliability to represent the geometrical complexity of components (e.g., irregular vaults, out-off-plumb walls, etc.) [11] and, (ii) the addition of a comprehensive semantic database of historical components, materials, information and notes regarding each building element and changes during time [12]. In addition, digital cultural resources have a great economical potential, even if often not fully exploited. Indeed, once a cultural heritage site is digitized it can have multiple uses. For example, it can be used for not only managing and conserve the digitized element but it may have different secondary uses like giving access to cultural heritage to citizens, researchers, having an impact on cultural and creative industries [13]. This way, the cost-effectiveness of the adoption of the digitization is increased. However, such exploitation of the HBIM is seldom preformed. In many cases, HBIM models are used only for case specific purposes limiting this way their general impact. On the other side, several works highlighted interoperability as a main gap to be overcome for an effective adoption of HBIM [14; 15; 16]. Indeed, the architecture, engineering, construction and facility management (AEC-FM) sector is very fragmented. In addition, when dealing with historical buildings further expertise (restorers, historians, archivists, etc.) are generally necessary to have an in-depth understanding of the building. For this reason, experts in several different domains collaborate on the same project. Some of them feeding the model with specific information (e.g., restores reports material and conservation state of elements, historians contribute in understanding the different historical phases etc. ), while some other query the HBIM model as a centralized model and extract specific information for the different construction domains (e.g., estimating, scheduling, supply chain and fabrication). Each construction domain has specific requirements and needs a specific set of information representing their views of the project. In addition, a further gap to effective interoperability is given by the fact that each sector stores their information in heterogeneous data formats [17]. However, the user of a BIM platform is limited to the platform schema and is not able to define information that falls out of it, as in the case of a HBIM project [14].