IFCs / BLIS

Sponsor

International Alliance for Interoperability (www.iai-international.org)     

An alliance of organizations within the construction and facilities management industries dedicated to improving processes within the industry through defining information models that promote the use and sharing of information.

Includes architects, engineers, contractors, owners, facility managers, manufacturers, software vendors, information providers, government agencies, research laboratories, universities, etc.

Currently 9 chapters: Australasia, France, the German Speaking countries, Japan, Korea, North America, the Nordic countries, Singapore and the United Kingdom.

Building Lifecycle Interoperable Software (www.blis-project.org)  

An international association of software vendors dedicated to implementing IFCs around a very specific set of use cases to support building information exchanges.

Web Site

IAI-IFCs - www.iai-international.org

BLIS - www.blis-project.org/index2.html

How to Obtain

IAI-IFC Specifications, Schemas and Documentation

BLIS Views (IFC subsets in EXPRESS) (and use left-hand navigation menu)

BLIS-XML (and use left-hand navigation menu)

Contact

IFC  - see web site

BLIS - (use left hand navigation menu - Contact Us - Regional

Usage

IFC - Exchange/share comprehensive building information models

BLIS - Exchange subsets based on IFCs that support specific use cases

Scope

IFCs-Data Object Model for Buildings.  Industry Foundation Classes (IFCs) are data elements that represent the parts of buildings, or elements of the process, and contain the relevant information about those parts. IFCs are used by computer applications to assemble a computer readable model of the facility that constitutes an object-oriented database of the information shared among project participants.

IFCs is a platform containing classes that provides the framework for the integration of models developed by projects and that provide for the sharing of information between domain areas.

A "core" model plus plug-in extensions software architecture was established to ensure structured extension of the IFC model with minimal disruption between releases. Four AEC/FM domains are addressed: architecture, HVAC engineering, construction management, facilities management. 

The BLIS models are subset ‘Views’ of IFC are designed to support the following end user ‘use cases.’

1. Design <--> Design (geometry view)

2. Client briefing/space planning --> Architectural design 

3. Architectural design <--> HVAC design 

4. Arch/HVAC Design --> Quantities take off / cost estimating 

5. Arch/HVAC Design --> Thermal load calculations / HVAC system design 

6. Arch/HVAC Design --> Construction management/scheduling

Characteristics

See Interoperability Tutorial for details on terms used below.

Domain

commercial + industrial buildings

Standard Type

deFacto

Standards Process

Standardize then Implement

Intellectual Property (IP)

Royalty-free EXPRESS or XML schemas.

Cost of one interface

unknown

File Format

ExPRESS-based Part 21 files 

Focus

BLIS is usage-driven and focused on exchange files to support specific use cases.  IFCs are intended to support a comprehensive building information model

Scope

IFC core architecture is re-usable by multiple subject domains.

Scalability

Intended for large scale exchange of comprehensive building information models.  BLIS subset views are less expensive and so more scalable.

Extensibility

Dynamically extensible data model.

Model Content

Mix of broad classification and shallow details, with deeper property details in some areas.

Usage

Primary usage is exchange files or messages associated with specific transactions,

Exchange Content

IFC uses the data model + data approach

Data model approach

Abstract core data model uses domain  terminology as data to dynamically extend data model.

Benefits

Supports an e-project model useful in sharing data across applications.

• Defined by the AEC/FM industry

• Provide a foundation for the shared project model

• Specify classes of things in an agreed manner that enables the development of a common language for construction

Status & Plans

IFCs Initiated in 1995.  BLIS initated in 1999.

Currently IFC R2X is an IAI recommended standard.

IAI has submitted the IFC R 2X specification for ISO recognition (ISO TC184/SC4 N1211)

SC4 Fukuoka resolution has kicked off the transposition process of IFC R 2X

IFC Release 3.0 Plan

Will significantly extend the domain coverage of the IFC Object Model. Models will use the platform developed by R2.X and will be issued on completion. 

Developing a methodology for encoding EXPRESS based information in XML format (BLIS-XML schema can be automatically generated from an EXPRESS schema).

Software

Current status of industry vendor software implementations are summarized here 

Deployment Status

Building Lifecycle Interoperable Software (BLIS): a coordination project that coordinates the implementation efforts of vendors seeking to support IFC R2.0 in applications.  BLIS web site:  http://www.blis-project.org/

Deliver increasing levels of application interoperability through semantic model sharing (objects, properties and relationships) and implementation collaboration

Most if not all of the current software deployments use the EXPRESS schema and the STEP Part 21 exchange file format for IFC R2.

Limitations

The difficulty of implementation: the large standard may cause high cost for implementation.

The broad size of IFCs can make simple data exchange complex.

The EXPRESS model STEP Part 21 File Format methodology is less familiar to software developers than XML.

Additional Resources

Available on the IFC and BLIS web sites.