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A Announcement
In This Issue
gbXML Webinar
API on GitHub
Test Cases
Validation Website
gbXML Schema Update
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Upcoming gbXML Webinar

"Using Green Building XML with Rhino 3D and Grasshopper," September 3, 2014 from 2:00 pm to 3:00 pm EST

We are holding our semi-annual gbXML webinar on September 3, 2014 from 2:00 pm to 3:00 pm EST. This webinar will demonstrate the integration of gbXML with building design tools such as the Rhinoceros 3D modeling tool, the Rhino plug-in Grasshopper and others. 

Presentations and product demos will include the following: 


Chien Si Harriman, Terabuild, will demonstrate the latest software development efforts to improve gbXML access to new workflows such as Rhino/Grasshopper and similar early stage conceptual tools. He co-wrote these workflows with the help of engineers from Carmel Software and Thornton Tomasetti's TTCore group.  

Stephen Roth, President of the and Principal of Carmel Software will also discuss the current status of the gbXML and related activities.

Reserve your webinar seat now at: Funded by Pacific Northwest National Lab


Earlier this year, we announced that PNNL agreed to provide further funding for improvements to the gbXML schema. Since then, we have completed Phase II of this effort, and it includes three major deliverables:

  1. Open-source API on GitHub: Allows you to create your own gbXML validation tools.
  2. Test case documentation: An additional series of documents that instructs you how to create valid gbXML files.
  3. gbXML validation web site: Allows you to upload a gbXML file to perform various levels of schema validation based upon the test case documents described in item #2 above. We have also updated it for Phase II so it performs more generalized gbXML validation.

The benefits of these deliverables include providing BIM authoring tool vendors direction on how to create valid and standard gbXML files that can easily be shared across many different types of building analysis tools including those that perform building energy modeling, HVAC load calculations, and lighting analysis. 

GitHubgbXML Open-Source API on GitHub

A brand new gbXML application programming interface (API) is available on GitHub. This allows anyone to create their own gbXML validation tools using C# (other languages will soon follow).


This is a clean set of classes that can be used to create a gbXML file to describe the geometry and thermal properties of a building for energy simulation.


To see these classes and productivity classes in action, you may want to refer to an implementation for Grasshopper, called Grizzly Bear (part of Mostapha Roudsari's Honeybee project on Github). Grizzly Bear is a working example of gbXML serialization transforming a set of base classes in another format to gbXML. You can witness how information needs to be gathered, and the flow of XML creation. This is the best example that we currently have in an open-source format for gbXML so that others can learn how to produce the base set of elements to describe building geometry and thermal properties for energy simulation.



DocsgbXML Test Case Documentation conducted industry research into which building geometry configurations caused the most problems in gbXML-based data transfer.  Out of this research, we generated sixteen (16) standard test cases (click here), each touching upon a particular aspect of modeling that focuses on creating valid geometric representations of a building volume (surfaces that make up the building enclosure). 
These tests cases are simple, small buildings, each containing some aspect of geometric modeling that has caused improper gbXML building representations in the past.
Interested parties who wish to understand how gbXML works can review the test cases and the set of instructions on how to construct the test case geometry.  These documents are intended to assist BIM (building information modeling) authoring tool vendors in generating valid gbXML files.
For example, Test Case 1 focuses on creating a valid representation of 2 walls of different thicknesses with parallel aligned faces.  The documentation offers a definition of the test case, a visual representation of it, and instructions on how to create a valid gbXML representation of the geometry, itself: 


ValidationgbXML Validation Website - Phase II

The gbXML validation website allows interested parties to upload their own gbXML files that represent each of the test cases described above. The validator performs the following 3 levels of verification:

  1. Level 1: Checks for a properly formed XML file
  2. Level 2: Checks for a properly formed gbXML file comparing it to the 5.10 and later schema versions
  3. Level 3:  Checks for the 16 standard test cases 
If the validator confirms that the file is not valid gbXML for the test case of interest, it will provide detailed reporting on exactly what caused the issue.

The Phase II development of the validator website focused on making it more generalized. Therefore, anyone with a gbXML file (even one not created according to the test documentation above)


Click here to go to the validator website. 

gbXML Schema Update (Version 5.12)

In early August, we released an updated version of the Green Building XML (gbXML) schema (5.12).
It includes over 20 updates, improvements and enhancements. Click here to view the new schema/change log.

EventsUpcoming Events

The following is a list of upcoming events that should be of interest to the gbXML community:


gbXML Webinar: 

September 3, 2014: We will be holding a live gbXML webinar to discuss the latest developments of Green Building XML. Click here to sign up: 


2014 ASHRAE--IBPSA-USA Building Simulation Conference  

September 10 to 12, 2014 in Atlanta, GA: ASHRAE and IBPSA-USA are convening this conference to improve the industry's ability to accurately model building performance. The conference merges the IBPSA-USA SimBuild and ASHRAE Energy Modeling Conferences. The focus is on making better decisions through the application of simulation and modeling over the entire building life cycle from the earliest concept through operation and maintenance.

Open Green Building XML Schema, Inc. (dba