The human needs that arise out of users’ interactions with a range of settings in the built environment are redefined as performance levels. Grossly analogous to the human needs hierarchy (Maslow, 1948) of self-actualization, love, esteem, safety, and physiological needs, a tripartite breakdown of users’ needs and their respective performance criteria parallels the three categories of criteria for evaluating building quality postulated centuries ago by the Roman architect Vitruvius (1960). These are firmness, commodity, and delight. This historic approach to setting priorities on building performance has been transformed into a hierarchical system of users’ needs by Lang and Burnette (1974), and synthesized into the ‘habitability framework’ by Preiser (1983) and Vischer (1989), among others. Three levels of priority are depicted in Figure 1.2 below. They are: 1. health, safety and security performance; 2. functional, efficiency and work flow performance; 3. psychological, social, cultural and aesthetic performance. Each category of objective includes sub-goals. At the first level, one sub-goal might be safety; at the second level, a sub-goal can be functionality, effective and efficient work processes, adequate space, and the adjacencies of functionally related areas; and, at the third level, sub-goals include privacy, sensory stimulation, and aesthetic appeal. For a number of sub-goals, performance levels interact. They may also conflict with each other, requiring resolution in order to be effective. As the three-part Figure 1.2 shows, the three hierarchical levels also parallel the categories of standards and guidelines available to building designers and professionals. Level 1 pertains to building codes and life safety standards projects must comply with. Level 2 refers to the state-of-the-art knowledge about building types and systems, as exemplified by agency-specific design guides or reference works like Time-Saver Standards: Architectural Design Data (Watson, Crosbie, and Callender, 1997), or the Architect’s Room Design Data Handbook (Stitt, 1992). Level 3 pertains to research-based design guidelines, which are less codified, but nevertheless equally important for designers. This hierarchical system relates the elements of buildings and settings to building users and their needs and expectations. In applying this approach, the physical environment is
The evolution of building performance evaluation:an introduction 5
considered as more than just a building or shell because of the focus on settings and spaces for particular activities engaged in by users. System elements, in effect building performance variables, can be seen as ascending hierarchies from small- to large-scale, or from lower to higher levels of abstraction