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|buildingSMART alliance Energy Information Exchange (ENERGie) Presentation|
Energy Information Exchange (ENERGie) Presentation
NATIONAL INSTITUTE OF BUILDING SCIENCES (NIBS) ANNUAL MEETING AND AEC/ECOBUILD
The Energy Information Exchange (ENERGie) projects goal is to harmonize the requirements of gbXML and the building elements of LEED within the context of an EnergyPlus compliant Model View Definition to provide a single life-cycle oriented exchange of energy analysis information. The work presented in this session extends the early design energy data exchange supported by the General Services Administration to include requirements for coordinated design. This session introduced the Model View Definition and provided demonstration demonstrations of various software pieces that will be used in the end-product.
The U.S. Army funded this development and demonstration.
The following presentations were given at the meeting:
Status: Information Requirements for LEED Design
There is growing interest in defining the information that must be transmitted from the design team to the LEED assessor and back. These exchange requirements are extensive, but the use of BIM models is expected to be increasingly important. The ENERGie project has developed process diagrams which highlight the exchange requirements in general terms and the functional parts which define the exact scope of the information required in technical terms. The analysis starts with the seven–part criteria:
For more information, see idm.buildingSMART.no.
ENERGY MVD for Detailed Design
Currently BIM models exported to IFC should contain sufficient information for the analysis of the envelope performance. More detailed analysis, for example of the energy flows between zones and spaces, require more detailed exports. In particular the IFC file can contain information on the way spaces touch the fabric elements such as walls and slabs. For more detailed design it may also be necessary to know how each patch aligns with patches on the other side of the fabric element. The conventions for documenting these increasingly complex relationships are the subject of a 'model view definition' which is prepared to help BIM tool vendors include this information in their exports, and to help Energy analysis vendors to import this information.
For more information, see mvd.buildingsmart.com.
gbXML and IFC
The preferred format for interoperability of facility information is IFC (ISO PAS 16739) developed by buildingSMART, which can be used for many interchanges during the facility lifecycle. An alternative format for interoperability is gbXML developed by Green Building Studio Inc., now owned by Autodesk, which is used specifically to transmit fabric and outline system information to Energy analysis packages.
In so far as the two standards can themselves be made interoperable, there will be a reduced risk that designers will be restricted in their choice of design application or analysis application. This freedom should benefit both designers and energy analysts. Designers have more freedom to choose their preferred BIM design application, and the energy analyst has more freedom to choose their preferred Energy analysis application, whilst still benefiting from reduced set-up times for their analysis applications. This should improve the transmission of the concept from the designer to the analyst and also the flow of results from the analyst back to the designer.
The primary pre-requisite for the deployment of this technology is in ensuring that facility designers and energy analyzers deliver their information in one of the interoperable formats. This expectation may need to be enforced by contractual terms, extra work items or separate negotiation. Education on the concepts and training in using the tools is vital. This is particularly necessary as interoperability depends on the more skillful and accurate exploitation of object based design tools for facility design, such as Bentley Architecture, Autodesk Revit, Vectorworks etc, and of analysis tools such as Green Building Studio, IES and Energy + .
The tools needed are available at zero cost.
Application Support for gbXML and IFC
(based on internet search performed May 2009)
gbXML is an XML format, IFC has an XML representation as ifcXML. XML is significant because the technology to read, write and transform XML has been standardized and is freely available. For example this project has built on a technology previously developed for USACE ERDC called 'bimServices'. 'BimServices' is a suite of command line utilities designed to effect systematic transformation of facility data. 'bimServices' uses the Microsoft .Net XSLT engine which could be replaced by other tools such as Saxon, Xalan, or AltovaXML. 'bimServices' uses a third party no-cost component 'ifcEngine' (developed by TNO Delft, Holland) primarily to convert IFC data between STEP (ISO 10303 part 21) and XML (ISO 10303 part 28) representations. This component is freely available subject to licensing conditions.
The key deliverables from the current project are the configuration "_fromGBxml.ifcxml.xsl" which embodies the mapping from the gbXML representation to ifcXML, and the configuration "_asGBxml.xml.xsl" which embodies the mapping from the ifcXML to gbXML representation.
The 'bimServices' suite is freely available from the website www.aec3.com under Tools. This includes documentation on usage.
The configuration files to support interoperability are _fromGBxml.ifcxml.xsl dated 2009-09-16, and _asGBxml. xml.xsl dated 2009-09-16.
No support or warranty is offered for bimServices, ifcEngine or its configurations.
"bimServices" is currently based on the IFC2x platform which has been guaranteed stable for the last six years and underlies the current release IFC2x3 and the next release ifc2x4. This last standard will be submitted for full ISO endorsement. "bimServices" can be installed on end user machines supporting Windows, or it can be configured as services behind a web-based design collaboration services such as NIBS ProjNetSM. The deliverables are based on version 0.39 of the gbXML schema and the ifc2x3 release of IFC. Vendors may be supporting earlier versions.