A comparative study of the IFC and gbXML informational infrastructures for data exchange in computational design support environments

Significant progress has been made in the area of common data exchange in the building industry with the development of information technology. Currently, the Industry Foundation Class (IFC) and Green Building XML (gbXML) are two prevalent informational infrastructures in the architecture, engineering and construction (AEC) industry. IFC and gbXML are both used for common data exchange between AEC applications such as CAD and building simulation tools. This paper presents a detailed investigation and comparative study of the differences between IFC and gbXML in terms of their data representations, data structures and applications. It aims to explicitly illustrate the complex data representation through  selected examples of the respective schema. Two specific demonstrative cases will include building element specification (i.e.,enclosure geometry) and building sensors (control and operation). Findings will be reported on the following aspects: (1) the strength and challenges of the diametrically opposing approaches between IFC and gbXML; (2) hierarchical structure of the schema in support of extensibility, data extraction, ease of implementation etc.; (3) formal adoption and application. Based on the results of this study, the gbXML schema is selected for development to demonstrate the features of gbXML. A proposed XML schema for lighting simulation will be presented. It aims to provide a seamless data integration platform between a CAD model (i.e., REVIT) and lighting simulation software (i.e., Radiance) in this study to support concurrent design of high performance buildings.