Introduction

Information management is becoming a critical issue for the construction sector. In fact, an ordered and regulated Building Information Management (BIM) is essential for an improvement of building processes. Among the main benefits, BIM enhances collaboration among stakeholders and disciplines and it prevents delays, cost overrun, errors and lack of performances during the whole building life cycle. Therefore, the implementation of BIM-based processes is gaining attention.

Particularly, different corporations and organisations (e.g., buildingSmart [1], EU BIM Task Group [2]) have put and are still putting great efforts in the definition of guidelines (e.g., [3]), in the development of research projects and in the proposal of best practises (e.g., [4]) at different levels and in different countries addressing BIM-related issues.

Within this context, INNOVance is an Italian research project that proposes and promotes an approach for the implementation of BIM in the building sector [5]. The project develops a standardised method for the production and coordination of information collected during the whole building life cycle. Particularly, the research has been carried out with a specific focus on:

  • the standardisation of information structures and data contents for collecting information around buildings during their whole life cycle;

  • the definition of a structure (database) for information collection;

  • the specification of alpha-numerical and graphical attributes to be modelled in BIM objects according to the defined information structures and data contents, proposing guidelines for the development of a BIM library;

  • the connection among BIM objects and information collected in the database through interoperable web-services;

  • the development of a web-portal for information fruition.

Firstly, INNOVance project defines a classification system for identifying and describing different objects in a standardised way. The classification system concerns not only products, but all the adopted objects and the involved actors during the building life cycle (Fig. 1).

Fig. 1
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INNOVance classification system

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Moreover, the research addresses challenges in the development of coherent libraries, particularly related to the standardisation of information structures and data contents, that are generally difficult because of the vast number of categories in the building industry [6]. For this reason, the research develops standardised technical datasheets for collecting information about all the objects listed in the classification system.

Furthermore, barriers arising during traditional building processes are also related to lack of transparency in storing and exchanging information. Therefore, INNOVance project develops an ad hoc database for managing the whole amount of information concerning the different levels of INNOVance classification system.

Moreover, it is recognised that standardised product data libraries have a great potential to improve global real-estate development and to increase productivity [6]. Therefore, the project develops guidelines to deliver both proprietary and interoperable BIM objects, linked to INNOVance database, as a support to BIM-enabled building processes. Ad hoc Add-inns have been developed also for the connection of information stored in BIM objects and in the external database (INNOVance database), avoiding information redundancy.

Finally, the fruition of the complete sets of information (stored in the database or linked to BIM objects) has been guaranteed through an open web-portal.

Methodology

Within the Italian context, the research project has been carried out for defining a standardised way for managing information. After illustrating the main key points of the project (Fig. 2), the paper presents the approach adopted for the development of the BIM library.

Fig. 2
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Main structure of INNOVance project

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Starting from a literature review and the interaction with several stakeholders, the research identifies a consistent structure for the information collection. In fact, within the project, the development of the BIM library is strongly connected to the standardisation of information. Particularly, the research identifies the information required for a complete description and identification of each object belonging to different levels of the classification system.

The information structure allows to provide unambiguous names for the objects and to describe them through standardised technical datasheets. The proposed information structures and data contents for information collection have been used as basis for the development of UNI/TS 11337-2 and UNI 11337-3 [7]. Simultaneously to the definition of information structure, a technical solution (database) has been developed for storing information. Moreover, guidelines for the development of the BIM library have been provided and IT-related solutions have been proposed for connecting information in the database to BIM authoring tools through interoperable web-services (Fig. 3).

Fig. 3
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INNOVance approach for linking BIM objects to information in an external database

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Particularly, the creation of the BIM library has been based on:

  • definition of a homogeneous structure for collecting information concerning all the objects listed in the classification system (Fig. 1);

  • development of a database for storing information, used as a unique repository of information;

  • definition of graphical standards for representing objects;

  • link of objects in BIModels to the database through a code;

  • development of a user-friendly interface for consuming and updating objects. The web-portal has been developed for uploading, accessing, updating and exchanging information in the database, that is software-independent and that allows the exchange of information through IFC.

Within this context, a standard procedure has been defined for collecting information in the BIM library, based on four main steps:

  • analysis and definition of objects of technical components to be modelled;

  • encoding of the components according to the INNOVance information structure;

  • creation of BIModels linked to datasheets of the components through a code;

  • verification of information stored in BIModels through a Model Checker.

The standard procedure to model BIM primitives (considered the actual vectors of information for the different phases of the building process) has been defined to make sure that BIModels actually carry the information useful for all the phases and for all the operators involved in a construction initiative.

Considering the difficulties of embedding all the attributes and features necessary to describe the real objects into the BIM primitives, the BIM primitives have been associated to a code. Through the code, BIM objects have been linked to the external database, where technical datasheets are stored.

Thanks to the collaboration with the manufacturers organisations, the technical datasheets contain either generic data, either product-specific data from the manufacturer.

This way, it is easier to maintain the BIM primitives: when, for any reason, there is the need for updating or modifying the technical datasheet of a product or a component, it is possible to update only the technical datasheet and the related database records, with no need for redefining the BIM objects.

As the code links the objects to the technical datasheets, any update is automatically received by the corresponding BIM primitive. Therefore, BIM objects do not need to be remodelled, simplifying the maintenance of the BIM library.

Background

BIM guidelines

Several corporations and organisations have developed and are still developing standards and guidelines concerning information modelling and management [8].

Among them, the British standards PAS 1192-2 [9] and PAS 1192-3 [10], the AEC (UK) BIM Protocol [11], the COBie Data Drops [12] and the RIBA Plan of Work [13] are clearly defining procedures, contract protocols and BIM implementation pathways. In relation to concepts concerning BIM objects,Footnote 1 the British standards refer to Level of Model Definition, Level of Model Detail and Level of Model Information. The concept of Level of Model Definition refers to the minimum detail level requested for each component of the model, within the frame of the permitted purpose that the full model would have to satisfy. The concept of Level of Model Detail refers to the graphic content. The concept of Level of Model Information refers to the text and to the data linked to the whole model.

In Scandinavia, 13 series of Finnish COBIM [15] present how to model different elements during the construction phases, suggesting three different BIM content levels:

  • L1 for collaboration and communication between designers;

  • L2 for energy analyses in the pre-design and sketch design phases and for quantity take-offs in bidding phase;

  • L3 for construction scheduling and contractor purchasing.

The American NYC DCC BIM Guideline [16] describes the Level of Detail to which a model is developed and its minimum requirements (Level of Development).

The Australian NATSPEC National BIM Guide [17] resumes the definition of Level of Development given by the American Institute of Architects: LOD describes the level of completeness to which a model element is developed. It describes the steps through which a BIM element can logically progress from the lowest level of conceptual approximation to the highest level of representational precision.

Singapore BIM Guide [18] recommends how BIM elements should be modelled in different disciplines at different project stages.

BIM libraries

Several BIM libraries have been yet developed, especially for collecting BIModels of products and components.

BIM libraries are generally proposed by vendor-neutral organisations, by software houses and by manufacturers.

The National BIM Library is an example of BIM library that meets the requirements of the internationally recognised NBS BIM object standard [14]. The abovementioned document defines general requirements, information requirements, geometry requirements, functional requirements, and metadata requirements for creating BIM objects.

BIM object, BIM store, SmartBIM are only some of the existing BIM libraries that provide different objects in several formats.

Autodesk Seek, RevitCity, ARCAT, BIM Components (for Archicad) are examples of BIM libraries developed by software houses in a proprietary format.

Also manufacturers have been affected by the innovation of building processes due to the implementation of BIM. Among the others, Siemens and Caleffi have developed BIM objects of their own products [19].

Problem statement and innovative contribution

The research stems from the analysis of existing BIM guidelines and BIM libraries for proposing an approach fine-tuned for the Italian context.

However, generally, existing BIM libraries contain geometric information and, as information is not collected in a standardised way, they do not provide a complete description of the objects and they do not easily allow the comparison of different products. Moreover, stored BIM objects belong to a restricted number of categories, not covering the whole systems adopted in a construction work. Hence, not all the stakeholders are interested in consulting information in BIM libraries.

Furthermore, many BIM libraries are software-dependent and not vendor-neutral. In fact, they generally do not rely on the exchange of information through Industry Foundation Classes (IFC), the standardised open format developed by buildingSmart [20]. IFC supports diverse national classification systems and different languages. Additionally, International Framework for Dictionaries (IFD) is a standard for terminology libraries or ontologies, representing object classes and their relationships [21]. However, a great concern in the use of libraries is related to the lack of tools supporting workflows that require the exchange of data based on IFC neutral format between consequent project stages [6].

Therefore, starting from the analysis of current BIM libraries, INNOVance project proposes guidelines and IT-related solutions for the development of a BIM library. Within the project, the BIM library is not considered a tool to speed up the BIModel creation, but to improve the information management for the whole supply chain. Particularly, INNOVance project recognises that collecting information within a BIM library allows to track the provenance of content and the responsibility of provided information.

Information management within INNOVance project

After an analysis of existing classification systems (Table 1), INNOVance proposes a system by which it is possible to classify every object, according to the function to be solved, the material of which the object is composed of or the activity required for its installation.

Table 1 Existing classification systems
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As an example, it is possible to describe every object, their links with lower and upper levels, and their links with other objects of the same level (referring to levels presented in Fig. 1). A wall can be described through the products of which it is composed of, can be localised within a building, can be connected to the activities occurred for its construction and can be enriched with the information for its installation and maintenance.

For describing objects belonging to the classification system, two levels of information have been further proposed: the unambiguous name and technical datasheets.

The unambiguous name is assigned through a predefined structure. The structure highlights the seven main characteristics of the objects: category, typology, function or standard reference, main performance, geometry, dimension and physical–chemical properties.

Through the unambiguous name, it is possible to identify groups of products with similar characteristics, without providing specific and detailed information. Therefore, this kind of information can be provided during the first stages of the building process or can be required for public procurements, when references to producers or manufacturers cannot be provided. In the following stages of the building process, information can be enriched through technical datasheets.

In fact, technical datasheets have been developed for describing objects in a detailed way. The structure is comparable for objects belonging to the same system (according to Fig. 1). As an example, the structure is very similar for products, layers and components, and assembled systems (objects of the technological system).

For the purpose of explanation, Fig. 4 provides an overview of the standardised structure of technical datasheets for construction products.

Fig. 4
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Main sections of technical datasheets for construction products

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Figure 5 provides an overview of the main section of the standardised structure for describing construction works, as buildings. Different dossiers (addressing specific Italian needs for the fulfilment of regulations, building codes and standards) have been proposed for the collection of information.

Fig. 5
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Main sections of technical datasheets for construction works

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All the different kinds of information are stored in a unique database, single repository of information of the whole project.

Information can be accessed through a web-portal, composed of different sections for object creation, object search, BIM library and BIM server [22].

The focus of the presented paper is the BIM library. However, an overview on the functions of the other sections is provided:

  • objects creation, allowing the definition of the unambiguous name and adding information to technical datasheets, according to the standardised structure of the database;

  • object search, to download and manage information related to all the stored objects, also with pre-formatted views targeted to different users’ categories (as clients, designers, contractors or manufacturers);

  • BIM server, to manage a project, from the early phases to construction, use, maintenance and disposal or handover. It can be used also as a repository, to store BIModels; database interoperability is guaranteed by the adoption of the IFC protocol.

The BIM library is structured as follows:

  • a section stores objects belonging to the technological system (AEC);

  • a section stores objects belonging to the technological system (MEP);

  • a section stores objects belonging to the whole construction work.

By accessing a specific section, not only the BIM object can be downloaded, but also all the information related to the object can be consulted, through the link to the technical datasheets of the object itself.

In fact, the BIM library is the link among the BIM server and technical datasheets (Fig. 6).

Fig. 6
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Extract from a case study of the link of information among different sections of the web-portal

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The BIM library has been structured in a homogeneous way so that several actors can benefit of it. Among them, manufacturers can upload information about their products in a standardised way. Construction companies can consume stored information about products and machineries in their projects, can load data related to layers, technical elements and assembled systems, and can add information related to the activities required for their installation. Architects and engineers can use objects (in particular, BIM objects) and connected information in their projects. Owners can collect information related to involved stakeholders, following the development of the project.

INNOVance BIM library approach

The research project proposes an approach for the creation of interoperable BIM libraries, linked to INNOVance database, as a support of BIM-enabled building processes. The INNOVance BIM library has been conceived to embed all the information needed by the various actors of the building process, and to guarantee a proper information exchange between stakeholders as well as software platforms.

Moreover, the requirement for operational standards have been highlighted. Particularly, common modelling procedures have been defined for guaranteeing the consistency of information within a BIModel, as well as of its final representation. Such standards are fundamental to properly manage a BIM-based building process. They refer both to graphical standards, useful for the graphical representation of a BIModel, as well as to modelling procedures and information content, this being the key point of a BIM-based process. Therefore, a set of concepts and requirements has been provided for addressing both the graphical and modelling issues, referring to national and international standards, interpreted according to the national frame of rules for the building process.

Particularly, for a proper implementation, several factors have been considered, as:

  • the representation degree in terms of information embedded into the model;

  • the authorised uses of the information, defining for what goals the data at a certain representation or modelling detail can be used;

  • the solution for exchanging information among different actors of the process, without redefining the model that has to be interoperable.

Within the proposed approach, BIM primitives have been linked to all the information needed during any phase of the building process, available through technical datasheets stored in the database and accessible through the web-portal. In fact, a bi-directional link has been established between the BIM object and the code generated through the platform and associated to every object recorded into the database. This way, the code guarantees the access to the properties recorded into the database. Interoperability has been ensured exporting the object, with the linked code, into the interoperable IFC format. Moreover, as information is stored within a web-portal, it is not related to proprietary formats. In fact, the development of interoperable web-services allows to access the information through different tools.

The way the work has been addressed complies with all the requirements that influential international sources [6] have pointed out as the indicator of advanced, if not ideal, solutions for a BIM library:

  • generic and manufacturer product-specific data;

  • users from the industry as a whole (building life cycle);

  • classification based on unified terms and properties;

  • BIM, model merging and IFC support.

However, during the development of the BIM libraries, some critical issues have been spot.

At first, for testing the approach, BIM objects have been developed using a specific BIM Authoring tool (Autodesk Revit) provided by a project partner (that is Autodesk Platinum Partner). Therefore, the technical features of the software used for modelling affect the method to create the objects.

The case of the layers defining a wall is a clear example: Autodesk Revit has a number of predefined categories, with specific predefined names, that are the only available in the system, and cannot be modified by the user. Furthermore, the thickness of the layer has certain physical limits that have to be taken in account: layers thinner than 1.6 mm have to be represented as virtual layers, with thickness equal to zero.

This might not be a big issue, thinking of the tolerances allowed by the traditional building process. However, as long as the goal is to maintain a certain degree of consistency among the virtual object and the real object, it is an issue to be taken in account, especially when thinking in terms of performances of the modelled object.

Another issue to be taken in account is the modelling strategy, that has to be consistent among the different objects, so thin layers have to be all treated in the same way.

For this reason, an Add-inn has been developed for linking BIModels to the codes generated by the database and for checking the consistency among a certain BIM object linked and the real features recorded into the database. Alerts are generated when, as an example, the code of a window is linked to a wall or if layers of a stratified system are wrongly associated to a wall.

In fact, the Add-inn provides, for objects based on layers, automated procedures to define the layers starting from the features recorded in the database.

However, independently from the specific modelling platform used for the creation of BIM objects, the research proposes modelling and representation strategies, that must refer to common standards, enabling the consistency of the information contents and their representation, despite the specific issues of the chosen modelling platform.

General modelling guidelines and standards have been set up, either for BIM primitives, or for complex models.

This is about giving a clear address on the information content of the 3D model, as well as on the 2D output graphics requirements, and on the modelling procedures.

Such standards, here aiming to the definition of the BIM library, are part of the guidelines addressing the implementation of BIM, and are a tool useful to check and verify the quality of the BIModels, as well as to assess the processes and the competences of the companies that are offering BIM-based solutions.

Furthermore, the standards might be a useful reference for educating and training qualified and certified BIM operators.

Benefits

By defining a standardised structure for the collection of information and by establishing the link among BIM objects and information stored in the database, the project ensures the consistency in properties, as name of attributes, value range, and unit of measure. Consequently, users have the possibility of comparing in an easy and immediate way information among different products. This way, a current barrier is overcome: in fact, existing BIM libraries generally provide different information for products belonging to the same categories, but uploaded by different manufacturers, making difficult to compare products of different manufacturers.

The structure for collecting information allows the possibility to collect not only geometric information, but a wide range of properties, as shown in Figs. 4 and 5 (e.g., thermal properties, instruction for installation, information on the site of a building).

Moreover, INNOVance BIM library is not based on proprietary formats for exchanging information, but the development of solutions for connecting information through interoperable web-services allows to collect data in a neutral format. In this way, the solution is not software-dependent, therefore, also the efforts and the difficulty in maintaining consistency between the representations for the different software over time are reduced [23].

Furthermore, different actors can access the information through the portal. Among them, manufactures can upload information concerning their products; designers can enrich their projects with this information; contractors and owners have the access to a complete amount of information (as for warranty, instructions for the installation); and facility managers can find the link between the project and the involved objects. Instead, generally BIM libraries address only manufacturers and are mostly design-orientated.

Moreover, INNOVance project ensures the management of the whole supply chain and entire building life cycle, by creating association between objects and properties, also allowing evaluations as energetic, environmental and economic analyses (Fig. 7). In fact, there is the possibility to link design information and project-related requirements (e.g., options delivered during the bidding and procurement phase), increasing the effectiveness and improving the quality of the final output [6].

Fig. 7
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Link among BIM objects and database through the code

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The developed information structure allows the link not only between attributes and properties of products, but also among different levels presented in Fig. 1 (e.g., products, equipment and whole building). This way, it is possible to identify all the products of which a building is composed of and to have access to their technical datasheets.

Therefore, every BIM object is connected to a great amount of information, even if the size of files is reduced because information is stored in the database and not in the model, but directly linked to the model itself through the code.

Conclusion

INNOVance project has proposed a standard procedure, useful to model BIM primitives being actual vector of information for the different phases of the building process.

The project is aligned with the increasing need for BIM-managed building processes, when BIModels are vehicles of the information useful for all the phases and for all the operators involved in a construction initiative.

The research has recognised that it is not possible to embed into the BIM primitives all the attributes and features necessary to describe the real objects. Therefore, through the proposed approach, all the information is recorded into the INNOVance database and linked through a code to BIM objects. In fact, the methodology developed during the project has been based on the association of BIM primitives to a unique code, linking the object to an external technical datasheet, stored in a database. Therefore, the proposed approach is open and interoperable.