IFC and XML: What is the Difference? Many AEC activities need common basic data, but our industry's data usage requires different standards for the many functions and roles of a project team. These standards fall into two major categories:
- IFC for object models
- XML for data exchange
Industry Foundation Classes (IFC)The International Alliance of Interoperability (IAI) has developed a file format for data objects called Industry Foundation Classes (IFC). The IFC format is non-proprietary and is available globally to any company that defines AEC objects. Digital objects, like "real" objects in a building, have geometry, a 3 dimensional (3D) description. Objects also have properties, like their product name, finishes, and cost. Some objects are "real" like a door; others are abstract, like construction cost.
The object model is an integrated database of the facility. Its fundamental consideration is the life cycle: inception, design, construction, operation, and demolition. Traditionally, a user could not rely on getting adequate data for asset & facility management at the end of the construction stage. The IFC concept enables you to pass this information to all participants in the developmental stages.
The IFC format does not standardize data structures in software applications, only the shared information. This allows shared object model components and building systems to behave the way a user wishes. IFC provides a framework for companies to produce interoperable software in order to exchange information on building objects and processes and creates a language that can be shared among the building disciplines. The IFC format describes the behaviour, relationship, and identity of a component object within a model. When these components form a system (such as a wall), IFC protocols dictate the behaviour of the system. eXtensible Markup Language (XML)XML is an outgrowth of the popular HTML code used to develop Web pages and sites. XML allows data to transact between different software applications, leading to a better way to communicate and transact information.
An aecXML is a industry-specific subset framework of XML-based schemas that facilitates communications between and among the various team members involved in the AEC process, including: architects, engineers, contractors, owner/operators, estimators, consultants, materials suppliers, and building product manufacturers. It is an extension of, rather than a replacement for, today's software and databases. Individually those tools function well and are fine-tuned for their domains. What's necessary is a vocabulary for exchanging their important AEC facts and figures between systems. An aecXML is not intended to be a format for transferring CAD drawings, but rather a technique for expressing what's in them. For example, an aecXML-formatted message can request a search for a particular type of sound-control insulation, but you can use a different aecXML formatted message to find a local contractor capable of installing it.
Where an IFC provides the information description, an aecXML can allow integration with other industry document and project management systems and data as an exchange mechanism.
The IFC and aecXML standards arose from requirements at the opposite end of the information continuum. The motivation for IFC is the global support of the representation of buildings and their parts through agreed common definitions. An aecXML is a representation mechanism for data that is developing into a convenient and simple transport technology.
In order to achieve effective product data integration across the extended facility lifecycle, IFC and aecXML are complementary technologies. Both are necessary for the efficient future of our industry. It is a safe bet that due to IFC and aecXML, contract documents will require the delivery of computable building models in an object-based format. | 
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