U.S. General Services Administration - Public Buildings ServiceOffice of the Chief Architect—Capital Construction ProgramIntroductionThe Warroad Border Station is a proposed 24,000 square foot border station located on the US/Canadian border in Minnesota (Figure 1). The project team is pursuing LEED silver certification. After discussions internally and with the project team, it was determined that rather than conducting an energy analysis on one or more particular project design options, such as evaluating mechanical system options or other specific architectural impacts on energy usage, the Warroad Border Station project would be used as a case study/survey on the current capabilities of energy, thermal comfort, and daylighting building analysis tools, leveraging the use of BIMs, to inform GSA project teams and to contribute to the development of the BIM Guide Series 05- Energy Performance and Operations. Figure 1Warroad Border StationFigure 2 shows a project Narrative1depicting the work flow of this case study. Using CAD data provided by theproject team, a BIM was constructed in Autodesk Revit and Graphisoft ArchiCAD. The resulting BIM models were evaluated in the following building analysis tools: Solibri Model Checker (model checker), Green Building Studio (energy), FLOVENT (CFD/thermal comfort), eQUEST (energy), ECOTECT (thermal, daylighting, and shading), Integrated Environmental Solutions (energy, thermal, daylighting, shading), and Riuska (energy).GSA’s National 3D-4D-BIM Program Warroad Border Station Pilot Study1Figure 1Warroad Border StationU.S. General Services Administration - Public Buildings ServiceOffice of the Chief Architect—Capital Construction ProgramFigure 2Warroad Border Station NarrativeAmajor focus of the study, in addition to evaluating the current functionality of the building analysis tools, was toevaluate the current state of interoperability between the tools and the project information available through theexisting CAD data and the BIMs constructed using that CAD data. Data schemas such as green buildingextensible markup language (gbXML), Industry Foundation Classes (IFC), DWG and DXF, and ACIS SolidModel (SAT) were all evaluated as part of this case study.Part I: Building Information ModelsSoftware DescriptionAutodesk Revit Architecture/MEP 2008 and Graphisoft’s ArchiCAD 10 are several of the leading BIM-authoring tools on the market today. Each allows for complete object-oriented design and information storage and transfer.Data Exchange MethodologyGSA’s National 3D-4D-BIM Program Warroad Border Station Pilot Study2U.S. General Services Administration - Public Buildings ServiceOffice of the Chief Architect—Capital Construction ProgramUsing existing CAD drawings provided by the project team, BIMs of the border station were created inAutodesk Revit and Graphisoft ArchiCAD. Both DWGs and DXFs were used to construct the models byimporting them into the BIM-authoring tools and tracing over the construction/drawing lines. Only layersincluding walls (internal and external), windows, doors, roofs, floors/slabs, spaces, dimensions, and structuralgrids were imported. Structural elements were ignored. Modeling ResultsWall thicknesses were based on both construction/drawing lines and construction details. Due to the tracingmethodology, space dimensions between the two models were not exact, though the minor variations thatexisted were negligible for analysis purposes. All the elements in both models were manually populated withrelevant thermal data to evaluate the ability of the BIM-authoring tools to capture this data during export.Spaces or zones were defined for all interior areas, including mechanical and elevator shafts, inter-constructionvoids, and plenum spaces. Figure 3 shows the resulting models.Figure 3CAD to Revit and ArchiCAD Models Part II: Solibri Model Checker (SMC)Software DescriptionSolibri Model Checker is a software that analyzes Building Information Models for integrity, quality, and physical safety. SMC can import a building model either using the IFC format or via a direct ArchiCAD link, visualize the design in 3D, check the model against a set of rules, create a report of the potential problems, and create and show presentations of interesting points of the design.2Data Exchange MethodologyGSA’s National 3D-4D-BIM Program Warroad Border Station Pilot Study3Revit ModelArchiCAD ModelArchitectural Desktop (ADT) ModelU.S. General Services Administration - Public Buildings ServiceOffice of the Chief Architect—Capital Construction ProgramThe Revit and ArchiCAD models were checked for accuracy using an IFC import into SMC. Modeling ResultsWall adjacencies, floor and roof connections, and space definitions were all confirmed. Figure 4a shows theRevit model displayed as spaces only within the SMC interface, and 4b shows the ArchiCAD model withsurfaces.Figure 4SMC Models (4a) (4b)Part III: Green Building Studio (GBS)Software DescriptionGreen Building Studio is a web-based building energy analysis tool developed by a company of the same name. Green Building Studio, Inc. developed the open Green Building XML schema that is used for intelligent data exchange. The Green Building Studio web service offers interoperability between building design teams using Autodesk, Graphisoft, and other CAD products, engineers using software such as DOE-2, EnergyPlus, Trane Trace700, IES VE and other tools for load analysis, HVAC sizing, and green analyses.3 Exports in the gbXML format are uploaded to the GBS web service, and a DOE-2.2 simulation is quickly run on the uploaded file, withall the relevant thermal data automatically populated based on building size and type. A number of outputs are then made available to the user, including a newly populated gbXML file, a DOE-2 Input File, and EnergyPlus Input File, and a VRML file. These output files are available for download for the user to be used in downstream applications. The first five runs of a project are free to the user, with additional runs priced based on building size. The user also has the ability to consider a number of design alternatives within GBS.Data Exchange MethodologyBoth Revit and ArchiCAD allow for gbXML exports, with ArchiCAD having a “direct link” to GBS via an ArchiCAD add-on. This direct link comes in the form of a user interface within
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