Industry Foundation Classes Models Research Articles

ROBUST IFC FILES TO IMPROVE INFORMATION EXCHANGE: AN APPLICATION FOR THERMAL ENERGY SIMULATION

Despite many efforts from software vendors, AEC community and researchers, interoperability is still one of the main issues regarding reliable and robust transfer of information among different applications. In most cases, the Industry Foundation Classes (IFC) files fail to provide proper interoperability between geometric building models (architects) and thermal simulation software (engineers). This causes time consuming interactions and manual corrections prompt to errors. This paper evaluated two approaches for an efficient and robust transfer of IFC models considering space boundary characteristics to conduct thermal energy simulation (TES). The first approach was a multi-platform process which IFC files could be used by different TES tools. The second consisted of a single-platform process in which a single CAD software with built-in energy simulation capabilities was used. The two processes were tested with a simple residential building. Results indicated that the first process still required manual corrections and its performance was influenced by the TES tool used. The second approach addressed the interoperability problems, but caused “software dependency”. It was found that geometry data reflecting different levels of space boundaries significantly influenced energy simulation results, indicating that proper definition of space boundaries improved the robustness of IFC files. This showed that IFC files can be enhanced to facilitate TES. This study also showed opportunities for improvement regarding interoperability and suggested other ways to tackle this problem.

A PROCESS TO DIVIDE CURVED WALLS IN IFC-BIM INTO SEGMENTED STRAIGHT WALLS FOR BUILDING ENERGY ANALYSIS

The amount of energy that buildings consume is currently attracting significant interest throughout the world, and considerable attention is being devoted to the development of green buildings to reduce energy consumption; how­ever, the current process being used to conduct building energy analysis has a significant shortcoming in that it cannot directly use building information modelling (BIM)-based representational data that includes a curved wall. Currently, the curved wall must be converted into segmented straight walls (SSWs) in the building model in order for the building energy analysis (BEA) program to be able to recognize and use the data. In this paper, we have proposed a segmentation process for curved walls in industry foundation classes (IFC)-based BIM for BEA. The proposed process consists of three sub-processes: 1) extracting data from the IFC model; 2) dividing the curved wall into several segmented straight walls; and 3) generating an INP file as a building description for DOE-2.2-based BEA. The proposed process will enable the engineers who are responsible for BEA to use a BIM-based model directly in the BEA program without having to do additional work. The proposed process can help ensure that the BEA results are accurate and reliable.

개방형BIM기반의 건축공사 개산견적을 위한 물량산출 적용지침 활용방안 기초 연구

Received 15 October 2014; received in revised form 3 April 2015; accepted 3 April 2015ABSTRACTIn recent years, numerous studies have attempted to extract quantity data by using BuildingInformation Modeling (BIM). In terms of open-BIM based quantity take-off at the earlydesign stage, only few studies were conducted in the field of cost engineering. A lack ofcompatibility of open BIM for information exchange is postulated as the cause. The IndustryFoundation Classes (IFC) extension model has been developed to accommodate the interoper-ability with quantity take-off software. Improvement of open BIM for quantity take-off needsexchange requirements and model guidelines. For this purpose, the quantity data of IFC mod-els were analyzed using BIM analysis tools. This paper also provides a proposal of require-ments on open BIM based quantity take-off at the early design stage. Further this study havebeen develop the interface system for open BIM based quantity take-off requirements withthe results on this study.Key Words:BIM Quantity Take-off (QTO), Building Information Modeling (BIM), IndustryFoundation Classes (IFC), Open BIM, Requirements

도로 프로젝트의 BIM 사례모델 구축을 통한 호환성 검증

Recently, BIM has been widely applying in civil engineering projects centering on the private construction industry in order to establish self guidelines for spreading in practice. However, most BIM technologies and software are based on the architectural projects. In these environments, it is not easy to apply the BIM to a infrastructure field. Even BIM standards with IFC (Industry Foundation Classes) are also focusing on architectural projects. Especially, both private and public sectors do not know about how BIM delivery system should be performed, and how such deliverable should be submitted to the government yet. Thus, we need to analyze an application level of BIM S/W (Software) in real projects and verify their interoperability. Besides, since there are not any common standards that can exchange IFC models for civil engineering projects, we have many issues in converting as-built infrastructure models into IFC and delivering their design documents to the government. Accordingly, this study aims to perform a BIM process with commercial software for real road project after a detailed design process is finished and verify interoperability between diverse BIM software for securing BIM data reliability.

상수도시설물의 유지관리를 위한 BIM모델 개발 및 BIM 데이터 관리방안

3D-based BIM(Building Information Modeling) technologies can be utilized effectively as a means of systematic management of facility information for safety assurance and effective maintenance of waterworks facilities. In this study, BIM models of water treatment facilities that can be used as basic data for BIM-based maintenance of waterworks facilities were developed. Information exchange and generality of the developed BIM models were evaluated by conducting interoperability analysis of IFC(Industry Foundation Classes) conversion models. In addition, the application of COBie(Construction Operations Building information exchange) was recommended as an effective countermeasure to deal with technical limitation regarding exchange and utilization of facilities-related information through current IFC models. The results of this study can contribute to the development of BIM-based maintenance system for waterworks facilities.

IFCCompressor: A content-based compression algorithm for optimizing Industry Foundation Classes files

As the commonly used open and neutral file format for Building Information Modeling (BIM) data, IFC (Industry Foundation Classes) aims to facilitate interoperability between various software platforms in the AEC industry. However, the IFC files generated from different systems often contain enormous redundant information, which will greatly limit IFC-based data storage and exchange, management, transmission and other applications. To address this issue, this paper presents a content-based compression algorithm, named IFCCompressor, for optimizing IFC data files. Its goal is to make a large IFC file as small as possible by reducing its redundant information. The algorithm is achieved through an iterative compression procedure based on an IFC model's tree structure. The optimization procedure can be lossless or be constrained by an error bound. Compared with pure compression (ZIP) regardless of information content, the presented algorithm starts with a comprehensive analysis of structure and content of IFC file, and then eliminates its redundant information without changing the original file format. Unlike partial model extraction methods, our algorithm results in a complete IFC model but with a more compact IFC physical file. In contrast with some commercial IFC optimization tools such as Solibri IFC Optimizer, the algorithm can make the size of IFC files smaller. The experimental results show that the algorithm is particularly effective for some office/residential building models with a large number of duplicated components. The compression rate with our algorithm is generally very high (the average is 40.32%) for tested cases. The online IFCCompressor tool and its demonstration can be accessed at: http://cgcad.thss.tsinghua.edu.cn/liuyushen/IFCCompressor/.

An algorithm to generate space boundaries for building energy simulation

We provide an algorithm based on graph theory to convert a three-dimensional architectural building model without defined thermal space boundaries into geometry suitable for import into a whole-building energy performance simulation engine such as EnergyPlus. Our algorithm expects input specified as an Industry Foundation Classes model, accepts a wide variety of input geometry, and is capable of accounting for a building's construction material configuration as well as its geometry. The described approach is limited to solid-to-solid heat exchange; solid-to-fluid and fluid-to-fluid heat exchanges are not considered. We analyze the performance of our algorithm on some test building models.

BIMQL – An open query language for building information models

In this paper we present the on-going development of a framework for a domain specific, open query language for building information models. The proposed query language is intended for selecting, updating and deleting of data stored in Industry Foundation Classes models. Even though some partial solutions already have been suggested, none of them are open source, domain specific, platform independent and implemented at the same time. This paper provides an overview of existing approaches, conceptual sketches of the language in development and documents the current state of implementation as a prototype plugin developed for the open source model server platform bimserver.org. We report on the execution of example test-cases to show the general feasibility of the approach chosen.

No-Schema Algorithm for Extracting a Partial Model from an IFC Instance Model

AbstractThis paper proposes an algorithm for extracting a partial model from an Industry Foundation Classes (IFC) instance model without an IFC schema or a complete IFC model view definition (MVD). The methods developed in previous studies require either an IFC schema or MVD and software applications, such as an IFC model server or a building information modeling (BIM) authoring tool, to extract a partial IFC instance model. The algorithm proposed in this paper generates a partial model by recursively extracting IFC data instances in referential relations directly from an IFC instance model file, and it relies solely on the internal data structure of an IFC instance model, without an IFC schema or a MVD. The algorithm extracts physical and nonphysical data instances relevant to the user’s selection of building elements by recursively iterating through data instances based on the rules specified in the algorithm. A set of required building elements is not defined on the spot; rather, a set of building elem...

InSpace3D: A Middleware for Built Environment Data Access and Analytics

Standardisation, archiving, and digital access of spatial data pertaining to built-up environments is an area acquiring increasing attention amongst several interest groups: policy makers, designers and planners, civil engineers, infrastructure management and public service personnel, building users. Initiatives such as the Building Information Model (BIM), Industry Founda- tion Classes (IFC), and CityGML are creating the information-theoretic backbone that guides the crucial aspects of quality, exchange, and interoperability of spatial data at the environmental and urban scale. However, due to the inherent scale, com- plexity, and detailed geometric character of building information data, extracting useful semantic and qualitative knowledge for accomplishing high-level analytical tasks is still an extremely complex and error prone process involving data intensive computing. We propose a uniform spatial data access middleware that can provide a combination of high-level, multi-modal, semantic, and quantitative-qualitative spatial data access and analytical capability. We present the core computational capabil- ities for the proposed middleware and present an overview of the high-level spatial model and its compliance with the industry standard IFC. A key theoretical contribution is a framework for investigating the computational complexity of deriving spatial artefacts within the context of building informatics. Additionally, we empirically investigate the feasibility and practicality of the derivation of spatial artefacts by conducting experiments on seven industry-scale IFC models. The experiment results show that, despite having non-linear polynomial increase with respect to time, deriving spatial artefacts is practical with large designs.

Ontology-Based Partial Building Information Model Extraction

The current application of building information modeling (BIM) in the construction industry is generally focused on using the complete building information model during the life cycle of the project. With more information being added to the model, the size of the model file and the difficulty to manipulate the model increase. However, different use scenarios may only require access to certain specific information stored in the model. In contrast with the ample research of ontology applications in construction knowledge management, research of ontology in construction modeling has been limited. Hence, the purpose of this study is to use ontology in the extraction of a partial building information model from the original complete model. The building information models covered in this study are in the Industry Foundation Classes (IFC) format, which is a widely supported open BIM standard. An ontology TBox is developed according to the existing IFC schema specifications. For each specific IFC model, an ontology ABox is generated at run time, combining the ontology TBox and the IFC instances in the model. The ABox works as an index in the partial model extraction algorithm. A prototype Java program based on the algorithm was developed to demonstrate and validate the algorithm using both a sample model and an IFC model from a real building. The results indicated that the use of ontology provides a valid way to deal with the technical complexity of IFC models.

A Unified Building Model for 3D Urban GIS

Several tasks in urban and architectural design are today undertaken in a geospatial context. Building Information Models (BIM) and geospatial technologies offer 3D data models that provide information about buildings and the surrounding environment. The Industry Foundation Classes (IFC) and CityGML are today the two most prominent semantic models for representation of BIM and geospatial models respectively. CityGML has emerged as a standard for modeling city models while IFC has been developed as a reference model for building objects and sites. Current CAD and geospatial software provide tools that allow the conversion of information from one format to the other. These tools are however fairly limited in their capabilities, often resulting in data and information losses in the transformations. This paper describes a new approach for data integration based on a unified building model (UBM) which encapsulates both the CityGML and IFC models, thus avoiding translations between the models and loss of information. To build the UBM, all classes and related concepts were initially collected from both models, overlapping concepts were merged, new objects were created to ensure the capturing of both indoor and outdoor objects, and finally, spatial relationships between the objects were redefined. Unified Modeling Language (UML) notations were used for representing its objects and relationships between them. There are two use-case scenarios, both set in a hospital: “evacuation” and “allocating spaces for patient wards” were developed to validate and test the proposed UBM data model. Based on these two scenarios, four validation queries were defined in order to validate the appropriateness of the proposed unified building model. It has been validated, through the case scenarios and four queries, that the UBM being developed is able to integrate CityGML data as well as IFC data in an apparently seamless way. Constraints and enrichment functions are used for populating empty database tables and fields. The motivation scenarios also show the needs and benefits of having an integrated approach to the modeling of indoor and outdoor spatial features.

An Evaluation of IFC-CityGML Unidirectional Conversion

Interoperability between building information models (BIM) and geographic information models has a strong potential to bring benefit to different demands in construction analysis, urban planning, homeland security and other applications. Therefore, different research and commercial efforts have been initiated to integrate the most prominent semantic models in BIM and geospatial applications. These semantic models are the Industry Foundation Classes (IFC) and City Geography Markup Language (CityGML) respectively. However, these efforts mainly: a) use a unidirectional approach (mostly from IFC to CityGML) for converting data, or b) Extending CityGML by conceptual requirements for converting CityGML to IFC models. The purpose of this paper is to investigate the potential of unidirectional conversion between IFC and CityGML. The different IFC concepts and its corresponding concepts in CityGML is studied and evaluated. The investigation goes beyond building objects, also including other concepts that are represented implicitly in building schemas such as building objects relations, hierarchies of building objects, appearance and other building characteristics. Due to the large semantic differences between IFC and CityGML standards, the schema mapping is based on a manual pragmatic approach without automatic procedures. The mappings are classified into three categories, namely ‘full matching’, ‘partial matching’ and ‘no matching’. The result of the study shows that only a few concepts are classified as ‘direct matching’, a few as well as ‘no matching’ while most of the building concepts are classified as ‘partial matching’. It is concluded that unidirectional approaches cannot translate all the needed concepts from both IFC and CityGML standards. Instead, we propose a meta-based unified building model, based on both standards, which shows a high potential for overcoming the shortages of the unidirectional conversion approaches.

IFC-Based Computational Support Tool for Managing and Using Design Planning Information: Case Application and Evaluation

Planning information generated during initial architectural design phases significantly influences subsequent phases, and is implemented into architectural design models during the design process. However, failures to manage and use planning information in Korean design offices remain common. Current design tools that incorporate planning information also do not address the issue of interoperability during the life cycles of buildings. To address these problems, the Industry Foundation Classes (IFC) extension model was developed to accommodate the need to manage and use planning information for cooperation between design offices carrying out multidisciplinary tasks. This paper introduces a purpose-built software tool that implements the IFC model and demonstrates the efficiency of the proposed method with the software tool.

Shared computer-aided structural design model for construction industry (infrastructure)

The current interaction between participants in a construction project requires much time and is often a cause of mistakes and misunderstandings. Improvement of this interaction may therefore contribute to an improvement of the construction process as a whole. The lack of interoperability is the main problem behind such interaction drawbacks. In this paper, an infrastructure for a technology transfer model, namely Shared Computer-Aided Structural Design (sCAsD) model, is developed. It is built upon three basic building blocks: the Standard for the Exchange of Product Model Data (STEP, ISO-10303) Parts 104 and 107, the CIMsteel Integration Standard (CIS/2.0) resources, and the Industry Foundation Classes (IFC) standard that is being developed by the International Alliance for Interoperability (IAI). The sCAsD model is an extension for the structural domain/view of the IFC model, providing professional standardization within the synergy effect of the IFC. The model infrastructure is explained and discussed in terms of model schemata. In addition, model feasibility is studied within two assessments for model schemata and model realization in the construction industry. The former assessment has verified the robustness and effectiveness of the model through using a model interface in data handling within an application of an integrated earthquake simulation. Meanwhile, the assessment of model realization has validated the roadmap of model implementation in the construction industry through IAI. The model has been accepted as a formal IAI project, namely ST-7, and is being supported by IAI Japan chapter.

Development of an Industry Foundation Classes Assembly Viewer

The construction industry has invested considerable effort into integration of project information in the last decade. One such effort is the definition of Industry Foundation Classes (IFCs) to facilitate data sharing across applications through a shared project model. In order to achieve the integration objectives, the industry software vendors need to commit to the implementation of IFC in their products. IFC is defined in EXPRESS, which is a platform-independent, object-flavored, data modeling language. The EXPRESS-based models must be translated into some programming language model for specific implementation. To achieve this, developers need to evaluate and select a suitable model and programming language for their implementation. Developers therefore need to understand both EXPRESS and a host of programming languages. This initial knowledge requirement may hinder the take-off or adoption of IFC-based implementation. This paper describes a software solution that reduces this initial knowledge requirement considerably by providing a .NET class library translation and an implementation view of the IFC model, based on the EXPRESS definitions. Complemented by the online documentation provided with the IFC definitions, the software provides a hierarchical view of the IFC-based programming objects with drill-down facility for developers to capture and appreciate the information requirement for specific objects.

IFC model viewer to support nD model application

Today, building information modelling (BIM) plays a crucial role in the research and development fields of construction information integration and interoperability. This paper, from an information technology point of view, outlines the definition and aims of the “3D to nD Modelling” project, a platform grant-funded project by UK’s British Engineering and Physics Sciences Research Council (EPSRC). It presents a scenario of widening BIM implementation into the overall aspects involved in the whole life cycle of a building project. Industry foundation classes (IFC) as a standard BIM specification has been adopted as a central information repository in order to deliver the integrated building information throughout the nD-driven assessments, evaluation and decision-making. This paper also focuses on the development of an IFC-viewer, which is defined as the holistic interface of the nD modelling tool. The techniques and methods including the auxiliary tools adopted in this development are detailed. This development presents a practical and economic way to reveal and retrieve the information of IFC models inclusively, structurally and visually.