Linked Data in Architecture and Construction

Automation in Construction 57 (2015) 175–177

Contents lists available at ScienceDirect

Automation in Construction journal homepage: www.elsevier.com/locate/autcon

Editorial

Linked Data in Architecture and Construction The topic of this special issue is why and how to use the Web of Data technologies (RDF, OWL) for building information management (BIM). Semantic Web technologies and Linked Data are topics of increasing interest to academics and industrial experts working on the usage of information technologies in the domain of architecture, engineering and construction (AEC). This increasing interest has resulted in the formation of a number of research communities and initiatives. One of these community efforts is the workshop series on Linked Data in Architecture and Construction (LDAC), which will have its third edition in Eindhoven in 2015 [1]. This workshop series provides an opportunity to communicate research results within the scientific and industry community surrounding the topic. From these efforts in the LDAC workshop series, two distinct community groups have now been formed, namely the W3C Community Group on Linked Building Data [2] and the BuildingSMART Linked Data Working Group [3]. The aims and goals of both initiatives, although overlapping in many regards, are focsing on separate issues: The W3C Community Group on Linked Building Data is hosted by the World Wide Web Consortium (W3C) and brings together experts in the area of building information modelling (BIM) and Web of Data technologies to define existing and future use cases and requirements for Linked Data based applications across the life cycle of buildings. A list of recommended use cases is to be produced by this community group. The envisioned target beneficiaries of this group are both industrial and governmental organisations who use data from building information modelling applications and other data related to the life cycle of buildings (sensor data, GIS data, material data, geographical data, and so forth) to achieve their business processes. They will benefit from greater integration of data and interoperability between their data sets and the wider Linked Data communities. The buildingSMART Linked Data Working Group [3] is responsible for building and maintaining a recommended version of an ifcOWL ontology as a derivate of the canonical IFC STEP EXPRESS schema. The ifcOWL ontology is used in Linked Data and Semantic Web applications that consume, process and produce IFC data. The group meets at regular intervals, both virtual and live, to keep track of and discuss possible enhancements to the ifcOWL ontology. The Linked Data Working Group is part of the Technical Room of BuildingSMART and closely interacts with the other working groups within the BuildingSMART organization. These efforts have by now resulted in a draft ifcOWL ontology that is made available via the group site [4]. The current special issue compiles some of the results, use cases and projects that were proposed during the 2nd International Workshop on Linked Data in Architecture and Construction (LDAC), which was organised on 26-27 May 2014 in Helsinki by Aalto University and Tekla [5]. The topic of this event stood at the basis of this Special Issue: why and how to use the Web of Data technologies (RDF, OWL) for building

http://dx.doi.org/10.1016/j.autcon.2015.06.007 0926-5805/© 2015 Published by Elsevier B.V.

information management (BIM). The interest to this question arises from the expected benefits such as the ability to easily link building information models to and from external data sources, to open the models to new use cases and applications, to enable decentralised publication of models, to support loosely coupled interoperation through cross-model linking and to utilise reasoning and other services developed in Semantic Web research. The topic was approached from two different perspectives: a VoCamp focused on use cases and vocabularies for the Web of Building Data, and the LDAC workshop presented and discussed possible technical solutions. Participants to the LDAC workshop were invited to publish an article in this Special Issue regarding their conclusions. Additionally, an open call for papers was spread that allowed submissions by researchers who could not attend. Reflecting this spectrum of the event, the articles submitted to this Special Edition can be categorized into those with a technical focus and those investigating use cases. 1. Technical track A first group of articles focuses primarily on the technical steps that have to be made in order to properly deploy semantic web and linked data technologies in AEC industry. In this regard, we expected authors to focus on technical issues standing in the way of full implementation and deployment of semantic web technologies in the field: how can concepts in parallel information models be linked to one another; how to manage a set of (decentralised) linked information models; how to technically link RDF graphs of building information to existing modelling and simulation applications in the AEC domain; how to produce and store Unique Resource Identifiers (URIs) from available building models (e.g. IFC models); which OWL profile to use for the representation of ontologies; and so forth. The article by Radulovic et al. [6], Guidelines for Linked Data Generation and Publication: an Example in Building Energy Consumption, focuses on making a set of guidelines available regarding the proper generation and publication of linked data, aiming specifically at the context of energy consumption in buildings. They outline that the generation and publication of Linked Data are intensive engineering processes that require high attention in order to achieve high quality, and since experience has shown that existing general guidelines are not always sufficient to be applied to every domain, more specific guidelines can be of considerable importance and value. The provided guidelines list the tasks that should be performed and the tools that can be used to achieve these tasks. Diverse alternatives are given and recommended routines are outlined. This is applied to a specific case about energy consumption of council sites belonging to the Leeds City Council jurisdiction. The article by Terkaj and Sojic [7], Ontology-based Representation of IFC EXPRESS rules: an enhancement of the ifcOWL ontology, gives a detailed indication of how the recent actions towards the development of an OWL version of the IFC schema (named ifcOWL) can be extended

176

Editorial

to consider IFC EXPRESS rules. These rules were not considered before in earlier conversion procedures. This paper presents an enrichment of the EXPRESS to OWL conversion patterns with OWL class expressions that specifically capture certain constraints of the IFC standard. Using these additional class expressions, ifcOWL robustness is improved, as well as its support for data integrity, consistency, and applicability across various scenarios of industrial application. The proposed addition has been implemented and tested against a specific use case, thereby indicating how the suggested version further improves the original ifcOWL ontology. As proper restrictions are now included in the ifcOWL ontology, it becomes possible to directly create RDF instances instead of having to go through an intermediate step in which an IFC file is converted into an RDF graph. In the third paper in the technical-oriented section, Juan GomezRomero et al. also provide an extension to the ifcOWL ontology: A fuzzy extension of the semantic Building Information Model [8]. As they indicate, open standards, such as the Industry Foundation Classes (IFC), have contributed to expand the adoption of BIM tools, but they have limited capabilities for cross-domain information integration and query. The Linked Building Data initiative might provide a way to address these challenges and create more formal and interoperable BIMs. In their paper, the authors present a fuzzy logic-based extension of emantic BIMs that provides support for imprecise knowledge representation and retrieval. A expressive fuzzy ontology language is proposed and a description is given through specific examples of how this language can be combined with a fuzzy reasoning engine. The resulting fuzzy semantic BIM enables new functionalities in the project design and analysis stages—namely, soft integration of cross-domain knowledge, flexible BIM query, and imprecise parametric modeling. A last technical paper aims at providing generic change management support for building products. Oraskari and Törmä present an article on RDF-based signature algorithms for computing differences of IFC models [9]. Such algorithms would allow to track which changes are made to a building model, output in IFC, at any moment of time in an architectural design and construction project. This is a complex issue, because IFC models often consist of a high number of anonymous nodes, which change ID between versions. Hence, the computation of differences between versions is challenging. When an IFC model is converted into an RDF representation, the uniform graph structure offers new algorithmic opportunities to address these challenges. These opportunities are investigated by the authors. An investigation is made of the ways in which unique and stable identifiers can be assigned to anonymous nodes, and a Short Paths Crossings Algorithm (SPCA) is then proposed to compute sets of paths with limited length from anonymous nodes taking into account their crossings 2. Use cases track In addition to the above primarily technical articles, a number of articles discuss specific practical use cases that show the benefits of using semantic web and linked data technologies in a BIM context. These investigations of practical use cases bring about novel use cases of information usage in the AEC domain. In particular, use cases involving the following topics were expected: • Interoperability • Reasoning and rule compliance checking • Data access and querying

A first use case that was presented focuses on the usage of semantic web services for online cost estimating from distributed information sources. Niknam and Karshenas start by indicating in their article, Integrating Distributed Sources of Information for Construction Cost Estimating Using Semantic Web and Semantic Web Service Technologies [10], how the collaboration and information exchange is central to any construction

project. This is also the case for construction cost estimating. This process requires information from a BIM model, estimating assembly and work item information maintained by contractors, and construction material cost data provided by material suppliers. Using semantic web technologies, these data can be accessed, combined and shared in a straightforward manner over the internet in a machine-processable representation. A use case is demonstrated, which particularly relies on the Simple Protocol and Resource Description Framework Query Language (SPARQL). Through this use case, the authors show that the estimating process is not fully automated, but it can be better streamlined by reducing human involvement in repetitive cost estimating activities. The second use case documented in this Special Issue has a very similar aim, as it also aims to related BIM model information with building component information. Costa and Madrazo combine both types of information in their article, named Connecting building component catalogues with BIM models using semantic technologies: an application case for precast concrete components [11], aiming to assist the design team in the assembly and dimensioning of structural components during the project phase. As they indicate, existing BIM technologies do not provide links with product components that are needed to facilitate the participation of manufacturers in the design and building processes. Using a Linked Data approach, this can be somewhat remedied, as information about building products can be made accessible via building component catalogues, so that semantic services implemented in BIM environments can consult these catalogues and select the building components that should be included in the BIM model. This system is tested for a catalogue of structural precast concrete components. The third use case article included in this Special Issue is presented by Corry et al., entitled A performance assessment ontology for the environmental and energy management of buildings [12]. In this article, an investigation is made of the ways in which semantic web technologies can be used to combine all sorts of energy-related data in buildings, so that the performance gap between measured and simulated energy performance level of a building can be made to increase. The article describes how heterogeneous building data sources can be transformed into semantically enriched information, and how a performance assessment ontology and performance framework (software tool) can use this heterogeneous data as a service for a structured performance analysis. A demonstrator is described by the authors to illustrate how heterogeneous data can be published semantically and used. References [1] 3rd International Workshop on Linked Data in Architecture and Construction, http://ldac-2015.bwk.tue.nl/2015. [2] W3C Linked Building Data Community Group, https://www.w3.org/community/ lbd/2014. [3] BuildingSMART Linked Data Working Group, http://www.buildingsmart.org/ standards/standards-organization/groups/linked-data-working-group/2015. [4] ifcOWL ontology development at BuildingSMART, http://www.buildingsmart-tech. org/future/ifcowl2015. [5] 2nd International Workshop on Linked Data in Architecture and Construction, http://linkedbuildingdata.net/ldac2014/2014. [6] Filip Radulovic, María Poveda-Villalón, Daniel Vila-Suero, Víctor Rodríguez-Doncel, Rául García-Castro, Asunción Gómez-Pérez, Guidelines for linked data generation and publication: an example in building energy consumption, Autom. Constr. 57 (2015) 178–187. [7] Walter Terkaj, Aleksandra Sojic, Ontology-based representation of IFC EXPRESS rules: an enhancement of the ifcOWL ontology, Autom. Constr. 57 (2015) 188–201. [8] J. Gomez-Romero, F. Bobillo, M.-a. Ros, Miguel Molina-Solana, M. Dolores Ruiz, MarÃ-a J. Martín-Bautista, A fuzzy extension of the semantic building information model, Autom. Constr. 57 (2015) 202–212. [9] Jyrki Oraskari, Seppo Törmä, RDF-based signature algorithms for computing differences of IFC models, Autom. Constr. 57 (2015) 213–221. [10] Mehrdad Niknam, Saeed Karshenas, Integrating distributed sources of information for construction cost estimating using semantic web and semantic web service technologies, Autom. Constr. 57 (2015) 222–238. [11] Gonçal Costa, Leandro Madrazo, Connecting building component catalogues with BIM models using semantic technologies: an application case for precast concrete components, Autom. Constr. 57 (2015) 239–248. [12] Edward Corry, Pieter Pauwels, Shushan Hua, Marcus Keane, James O'Donnell, A performance assessment ontology for the environmental and energy management of buildings, Autom. Constr. 57 (2015) 249–259.

Editorial

Pieter Pauwels Ghent University, Department of Architecture and Urban Planning, Belgium Corresponding author. E-mail address: [email protected] Seppo Törmä Aalto University, Department of Computer Science, Finland E-mail address: seppo.torma@aalto.fi

177

Matthias Weise AEC3 Deutschland GmbH, Germany E-mail address: [email protected] Thomas Liebich AEC3 Deutschland GmbH, Germany E-mail address: [email protected] 24 January 2015

Jakob Beetz Technical University Eindhoven, Department of the Built Environment, Netherlands E-mail address: [email protected]