Advanced Building Simulation

192 Augenbroe
initiatives began in the early 1990s with European Community funded research
programs such as COMBINE (Augenbroe 1995) and local industry funded efforts such
as RATAS (Bjork 1992), both targeting design analysis applications. An industry sector
specific effort that started around the same time was CIMSTEEL, which targeted analysis,
design, and manufacturing applications in the steel industry (Crowley and Watson
1997). These projects have had a major influence on the early thinking about building
models and created the momentum toward efforts that followed, the most significant of
which was started in 1995 by the International Alliance for Interoperability (IAI). The
IAI has worldwide chapters with industrial and academic members that jointly contribute
to the development of a comprehensive building model, strangely called
Industrial Foundation Classes (IFC), although its aim is limited to the building industry
(IAI 2002). The IFC model is an ongoing development, and although still far from complete
is without doubt the most important industrial-strength landmark in AEC product
modeling efforts to date. The development of a building model of the intended size of
the IFC is a huge undertaking and in fact inherently unbounded unless the intended
scope and usage requirements of the model are specified explicitly. Some of the issues
that relate to the construction and implementation of a building product model are
discussed later.
Figure 8.2 shows the example of four applications sharing information through
a common representation, which will be referred to as the Building Model. The goal
of the Building Model is to conceptually describe (all or a subset of) building components
and abstract concepts and their relationships. Components can be defined
through their compositions, functions, properties and other attributes. The choices
that are faced in the definition of scope and nature of the semantic descriptions raise
questions that may lead to different answers in each case. Different building models
may therefore differ significantly in their structure and the abstractions that they support.
Another important distinction is the way in which the modeler views the world
around him, that is, as things that have an intrinsic meaning or as things that are
A
Energy
consultant
B
HVAC
designer
STEP
Building
Model
Physical
format
Figure 8.2 Data exchange through a central Building Model.
D
Costing
expert
C
Architect