A METHODOLOGY OF MAPPING INTERFACE FOR ENERGY PERFORMANCE ASSESSMENT BASED ON OPEN BIM

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1 Y. Ikeda, C. M. Herr, D. Holzer, S. Kaijima, M. J. Kim. M, A, Schnabel (eds.), Emerging Experience in Past, Present and Future of Digital Architecture, Proceedings of the 20th International Conference of the Association for Computer-Aided Architectural Design Research in Asia in Asia CAADRIA CAADRIA 2015, 2015, , The 2015, Association The Association for Computer-Aided for Computer-Aided Architectural Architectural Design Research Design Research in Asia (CAADRIA), in Asia (CAADRIA), Hong Kong Hong Kong A METHODOLOGY OF MAPPING INTERFACE FOR ENERGY PERFORMANCE ASSESSMENT BASED ON OPEN BIM JUNGSIK CHOI 1, MINCHAN KIM 2 and INHAN KIM 3 13 Kyung Hee University, Yongin City, South Korea {jungsikchoi, ihkim}@khu.ac.kr 2 Kyung Hee University, Yongin City, South Korea mchan07k@gmail.com Abstract. Early design phase energy modelling is used to provide the design team with feedback about the impact of various building configurations. For better energy-conscious and sustainable building design and operation, the construction of BIM data interoperability for energy performance assessment in the early design phase is important. The purpose of this study is to suggest a development of BIM data interoperability for energy performance assessment based on BIM. To archive this, the authors have investigated advantages of BIM-based energy performance assessment through comparison with traditional energy performance assessment; and suggest requirements for development of Open BIM environment such as BIM data creation and BIM data application. In addition, the authors also suggested on BIM data interoperability system and developed mapping interface. Keywords. Building Information Modelling (BIM); Energy Performance Assessment (EPA); Data Interoperability; Energy Property; Industry Fou dation Classes (IFC). 1. Introduction The increase of CO2 emission causes global warming and accelerates the environmental pollution. Statistic shows that construction sector takes up the 23% of overall energy consumption therefore it is needed to emphasize the necessity of building energy performance analysis as part of the national policy. Buildings bring along social and economic profits within its life cycle but they might cause serious environmental destruction due to the use of energy, water and other natural resources. Such destructions must be mini-

2 418 2 J. CHOI, M. KIM AND I. KIM mized for a green society. So the importance of the concept of green buildings, which can reduce energy consumptions, is on the rise and this is a national issue. Belonging to various fields of business, subjects on the introduction of BIM to build green building are actively being executed to utilize efficiently the information that occurs in the construction industry so that various energy performance analysis assessment of building would be possible in the early design phase. BIM has the capacity to manipulate changes from the 2Dbased to 3D-based design, generate and manage the overall information that is produced during the life cycle of a building. It can also provide prior review, cost estimating, quantity take-off and energy analysis from the building design phase. The energy performance analysis using BIM greatly reduces time and cost because the BIM data model already contains more than 70% of the information for building energy analysis. Especially when energy performance analysis could be conducted possible at the early phase of design, we will be able to expect more efficiency in comparing the design alternatives on energy performance aspects. However, the energy performance analysis in the current environment of Open BIM is still difficult to be seamlessly applied, due to uncertainty and lack of initial building input data and lack of interoperability between BIM softwares and Energy analysis programs. Therefore, it is necessary to develop the requirements for the energy performance assessment within the environment of Open BIM. Resolving such issue would thus allow an actively accurate and effective energy performance assessment capable within the BIM environment. The purpose of this study is to maximize the effective use of BIM application towards eco-friendly solutions, with identifable environmental conditions and requirements in the early phase of design, specifically towards the effective application in the evaluation of energy performance assessment in Open BIM environment. This would allow the energy performance assessment to be presented within the established Open BIM environment. Research on the concept of Open BIM and an overview of the energy performance assessment; and identify the status of applied Open BIM through case studies. Configure the requirements for energy performance assessment in the Open BIM environment theorem separated by aspects of the creation and application of BIM data; then identify specific details on the necessity and applicable measures for each requirement. Establish Open BIM environment for energy performance assessment by priority of requirement and can thus be applied at the level of initial research for

3 A METHODOLOGY OF MAPPING INTERFACE FOR energy performance assessment in the Open BIM environment. This contains proposal to a compatible system for BIM data and a developed mapping interface for supporting data transformation. 2. Energy Performance Assessment in the open BIM Environment 2.1 OVERVIEW OF THE ENERGY PERFORMANCE ASSESSMENT The traditional energy performance assessment process may cause erroneous interpretation when relevant information such as drawings, photos, and other project information are entered manually to provide for the energy model; and when changes occur to the design model and that of the energy model has to be done separately, this causes extra work effort. On the other hand, building data in BIM environment can include various parameters such as building s representation information, construction type and thermal properties for energy performance assessment. This saves time and increase the accuracy compared to the existing process and the results of the analysis can be quickly reflected. The BIM data model after being initialized is passed on to energy analysis softwares exported through IFC file type. At this point the BIM data including the parameters for energy performance assessment such as building shape information, construction type, and thermal properties are being imported into energy analysis software directly or indirectly. The resulted values of the energy performance assessment are feedbacked to the architects whom would be able to make design alternatives accordingly. Therefore, the subsistence of data interoperability for energy performance analysis softwares is very important to the reliability of the results of the energy performance rating. 2.2 CASE STUDY The concept of eco-friendly construction is an ongoing national issue and there is a growing trend in applying BIM-based energy performance analysis, depending on the activation of BIM. (1) Norway International Competition of National Art Museum In this project, automatic model validation and quality control was performed during the BIM model International competition examination step1. The area of the building surrounded by the external wall and the slab were automatically calculated according to the referenced values of the thermal resistance to heat loss using EDMmodelServerLite self-developed program.

4 4204 J. CHOI, M. KIM AND I. KIM (2) KPX (Korea Power Exchange) Design Competition for head office A design review report on eco-friendly construction were submitted for this project, written in its original BIM model format as well as IFC2X3 open format. Visual checks, functional quality checks and energy efficiency analyses were proceeded with. (3) PPS (Public Procurement Service) BIM guidelines BIM guidelines was announced in 2010 for the purpose of providing BIM working standards. This guideline has been defined for utilizing BIM on reviewing of energy efficiency during design stage. It is very important for future application because it is mandated to apply BIM from 2016 onwards. 3. Requirements of BIM environment on energy performance assessment The requirements for energy performance assessment in Open BIM environment are separated by aspects of the initialization of BIM data, utilization of BIM softwares and application. 3.1 ASPECTS OF THE INITIALIZATION OF BIM DATA Development of BIM usage scenarios Advancement of the common standard has to be done through BIM usage scenarios development; a step by step application within the scope of energy performance assessment of buildings. To achieve this, the work considered in energy performance assessment phase are defined and then drawn into detailed usages through comparison and analysis between the existing work process and BIM work process. For example, Energy Plus, the suggested software for examination of energy efficiency in the PPS guideline can define design variables as per energy performance analysis target. Therefore, the rules of regulation, software representation and common business rules have to be properly reflected to relate to BIM properties for heat loss in such case Development of BIM model guideline The guideline needed for standardizing modeling in the BIM data initialization phase should allow for Open BIM invigoration, effective application and evaluation. The modeling standard is compartmentalized into common standard and detailed standard for specific purpose. The common standard consists of basic contents for BIM model creation, and the detailed standard

5 A METHODOLOGY OF MAPPING INTERFACE FOR consists of related contents as per specific purpose. Specific contents might contain a lack of interoperability towards energy performance assessment target, purpose or properties of detail and level of detail (LOD). Nowadays, common BIM model guideline is consistently being developed but few focused on energy performance assessment. BIM model guideline including input variables of specific definition have to be developed because energy performance assessment requires specific information and function. Figure 1 is an explanation of BIM modeling creation example by BIM modeling standard (OGC-BPEA). Figure 1. Example of BIM modeling creation (OGC-BPEA Test case) Construction of BIM property system Many input variables such as material properties (Wall, Windows, Slabs etc.), building types (Light, Medium, and Heavy), building geometry information, location, weather data, building operation scenarios and so forth are required for common energy performance assessment. Nevertheless, the required input variables bear different property information system from the standard of BIM assessment, causing problem of imprecise energy analysis. Therefore, constructing specific property mapping system between energy performance assessment requirements and BIM object properties can make possible an accurate energy performance assessment in BIM process. It is needed especially to connect between building object properties and BIM software representations through mapping interface in energy performance assessment.

6 422 6 J. CHOI, M. KIM AND I. KIM 3.2 ASPECTS ON BIM DATA APPLICATION Analysis of BIM data interoperability system Softwares supporting energy performance assessment are dissemblance. It causes problem with standardizing data interoperability or partial data lost. Therefore, the BIM data interoperability system has to be able to analyse and resolve problems of objectivity and accuracy decline. To overcome this drawback, it is important to establish a case-by-case analyzing structure within the data interoperability system, to cope with the various aims and compositions per software. Most of the energy performance analyses were based on the gbxml format but there is a need for interoperability discussion on softwares that supports the IFC format of BIM data representation Development of Open BIM supporting Viewer To check the energy performance assessment objects and results, there is a need to develope energy performance assessment visualization system. This system has to support BIM data information and visualization of property information for energy performance analysis assessment. Furthermore, there is a need to develope a converter for the parts that are hard to solve through existing method in BIM data interoperability system. 4. Development of mapping interface for energy performance assessment based on Open BIM 4.1 SUGGESTION ON BIM DATA INTEROPERABILITY SYSTEM There are two kinds of the energy performance assessment process. One is within the design phase during BIM data initialization, using BIM softwares. The other is of the energy analysis phase applied from the design phase, by utilizing energy analysis softwares. In the design phase, many softwares are being used in domestic environment like ArchiCAD, Revit and Digital Project etc. In the energy analysis phase, Energy plus, Ecotect, IES/VE, Riuska etc. are used for various aims. Normally the IFC and the gbxml formats are considered for interoperability but the IFC data format on Open BIM environment is the main focus of this study. Furthermore, the decided energy performance analysis data format is the IDF format of Energy plus software, which is suggested by the PPS. The IFC file includes building representation information, material information and other information for energy performance assessment in the design phase. Consequently partial IFC information is needed to be trans-

7 A METHODOLOGY OF MAPPING INTERFACE FOR ferred to the Energy plus. In the transfer process, importing of different property systems as per energy performance analysis from different softwares causes confusion due to the nonstandard data interoperability system. Therefore, this study strives for a proposal to a median process between the design phase and the energy performance analysis phase for supplementation of data information loss and creation of additional information. Figure 2. Process of energy performance assessment in the BIM environment. 4.2 DEVELOPMENT OF MAPPING INTERFACE In this study, a mapping interface was formed for supporting the data converting phase for data interoperability between the design phase and the energy performance phase. The mapping interface is not simply a middle-ware and it can save users time by reducing the complexity of data transfer to Energy Plus. It can also identify and change parameters that contain building data, including in the IFC file, before importing into the energy analysis software. The mapping interface includes the basic IFC object viewer which is able to visualize IFC file. The interface can convert the IFC data format to IDF data format by using building object's representational information and property information. The interface of the mapping interface is shown in Figure 3. In addition, mapping interface provides function, Material Manager, that users can input and modify material information of building. Thought this function, users can not only modify material code but also input material code to the objects whose code is omitted. This function provides various and useful input environment by providing individual-input mode and multiinput mode. The interface of the material manager is shown in Figure 4.

8 424 8 J. CHOI, M. KIM AND I. KIM Figure 3. Interface of mapping interface Therefore, this mapping interface provides supplementation function that can input missed material information of building and edit function for various alternative review of building energy performance in prior phase of energy simulation. Figure 4. Interface of material manager The mapping interface is composed of five functions. The functions are label checking, viewing, mapping, converting, and simulation; as shown in Table 1.

9 A METHODOLOGY OF MAPPING INTERFACE FOR Table 1. Main functions of the mapping interface. Function Checking Viewing Mapping Converting Simulating Contents - Material Information of IFC Model - Automatic System of Space Information between Building Objects - Checking curved surfaces and non-parametric elements - Checking of Applied Material Library code Information - Visualization of IFC Model Parametric Information - Checking and Modifying Energy Relation Properties Information Between IFC Models - IFC Material Information and Material Library Information Linkage - IFC Properties Extract for Energy Analysis - Parametric Converting Module for IDF - IFC Data Convertion - Material Information Convertion - Parametric Information Convertion - IDF Data File Export - Viewing Module for Energy Analysis Results - Alternatives Reviewing Module - Report Producing Module 5. Conclusion The energy performance assessment of the buildings is getting more popular in early design phase using BIM, due to the rising low-carbon and ecofriendly design in issues of environmental problem. However in the current environment of Open BIM, there are problems with the lack of initial values of building information and lack of interoperability between BIM softwares and energy analysis softwares. This study concludes, in which to develop the requirements for energy performance assessment within the Open BIM environment is by actively inducing ways in resolving the degree of accuracy and effectiveness towards the process of energy performance assessment within the Open BIM environment. For this, the study suggests a BIM data requirements to be implemented in the early design phase to evaluate the energy performance assessment within the Open BIM environment. In sequence, the authors suggested the data conversion process after recognizing and solving the data interoperability problem for the BIM data interoperability system. From this stage, the mapping interface development contents were included to complement the loss of information and additional information occurred during data interoperability of between IFC and IDF formats. This study, however, being at the early stages of the current study, is limited to carrying out only some of the requirements from a variety of energy

10 J. CHOI, M. KIM AND I. KIM performance assessment in the Open BIM environment. Therefore, further research should be conducted through suggesting ways of problem solving in the overall requirements. The mapping interface, moreover, needs continuous improvement and supplementation to its user interface. Acknowledgements This research was supported by a grant (14AUDP-C ) from Architecture & Urban Development Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government. / This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No ). References ECBCS : 2008, IEA Energy Conservation in Buildings & Community Systems Programme (ECBCS) Strategic Plan Kim, Y.: 2009, Energy Saving and Building Energy Analysis Program for Green Building Design, Journal of the KARSE, 26(9), Moon, H., Choi, M. and Park, J.: 2009, Building Performance Analysis Interface based on BIM, Journal of the Architectural Institute of Korea Planning & Design, 10, Kim, I., Jin, J. and Choi, J.: 2010, A Study on Open BIM based Building Energy Evaluation based on Quantitative Factors, Transactions of the Society of CAD/CAM Engineers, 15(4), Schlueter, A. and Thesseling, F.: 2009, Building information model based energy/exergy performance assessment in early design stages, Automation in Construction, 18, NIBS: 2009, Overview Building Information Models. Available from: Open Source Repository < Kvarsvik, O. K.: 2009, National Museum at Vestbanen Architect competition BIM requirements and results, STATSBYGG. PPS: 2013, BIM Guide of Public Procurement Service v1.2. OGC: 2009, AECOO-1 Testbed Information Delivery Manual (IDM) for Building Performance and Energy Analysis (BPEA) Thread. Kim, I., Kim, J. and Choi, J.: 2011, Development of the IFC based IDF Converter for Energy Performance Assessment in the Early Design Phase, Transactions of the Society of CAD/CAM Engineers, 16(2), Bazjanac, V.: 2008, IFC BIM-based methodology for semi-automated building energy performance simulation, CIB W International Conference on Information Technology in Construction, Santiago, Chile. Kim, I. and Choi, J.: 2014, A Study on the Construction of Object Library System and the Verification of Interoperability for open BIM-based Energy Performance Assessment, Journal of the Architectural Institute of Korea Planning & Design, 30(7), 3-10.