Assuming the availability of a more general building data model, one must define life and fire safety features of a building before any automatic checking can be performed. Object oriented data structures are beginning to be applied to design objects, since they allow the type versatility demanded by design applications. As one generates a functional view of the main data model, the software user must provide domain specific information. A functional view is defined as the process of generating domain specific data structures from a more general purpose data model, such as defining egress routes from wall or room object data structure. Typically in the early design phase of a project, these are related to the emergency egress design features of a building. Certain decisions such as where to provide sprinkler protection or the location of protected egress ways must be made early in the process.

The term "model" in the above paragraph has been used in various ways and in this context is defined as any representation through which design intent is expressed. This includes accurate/ rational or abstract drawings (2- dimensional and 3-dimensional), physical models (realistic and abstract) and computer models (solid, void and virtual reality). The various models that fall within the categories above have been derived from the need to "view" the proposed design in various ways in order to support intuitive reasoning about the proposal and for evaluation purposes. For example, a 2-dimensional drawing of a floor plan is well suited to support reasoning about spatial relationships and circulation patterns while scaled 3-dimensional models facilitate reasoning about overall form, volume, light, massing etc. However, the common denominator of all architectural design projects (if the intent is to construct them in actual scale, physical form) are the discrete building elements from which the design will be constructed. It is proposed that a single computational model representing individual components supports all of the above "models" and facilitates "viewing"' the design according to the frame of reference of the viewer.

Furthermore, it is the position of the authors that all reasoning stems from this rudimentary level of modeling individual components.

The concept of component representation has been derived from the fact that a "real" building (made from individual components such as nuts, bolts and bar joists) can be "viewed" differently according to the frame of reference of the viewer. Each individual has the ability to infer and abstract from the assemblies of components a variety of different "models" ranging from a visceral, experiential understanding to a very technical, physical understanding. The component concept has already proven to be a valuable tool for reasoning about assemblies, interferences between components, tracing of load path and numerous other component related applications. In order to validate the component-based modeling concept this effort will focus on the development of spatial understanding from the component-based model. The discussions will, therefore, center about the representation of individual components and the development of spatial models and spatial reasoning from the component model. In order to frame the argument that spatial modeling and reasoning can be derived from the component representation, a review of the component-based modeling concept will precede the discussions of spatial issues.

The research described in this paper is the result of exploring the concept of using computer graphics to support energy efficient building designs. It focuses on the visualization of building energy through a highly interactive graphical interface in the early design stage.