Decision-making in the design process is multi-dimensional, involving various stakeholders with diverse perspectives and interests. This results in the need to undertake multicriteria decision-analysis (MCDA). The process of MCDA fundamentally involves breaking the decision problem into elements, evaluating each element separately, and reintegrating the elements for a holistic perspective.
Choosing by advantages (CBA) is a form of MCDA in which decisions are characteristically based on comparing the advantages of alternatives . CBA, as a lean decision system, creates a participative and transparent environment for collaborative and auditable decision-making. The CBA process involves seven systematic steps (Figure 1).
However, time and resource constraints, coupled with the expandable nature of design decisions, make it practically impossible to apply all the seven steps on every decision in a design process. This impracticality of applying CBA, especially in the case of the tabular method, to every decision in the design process spectrum then results in the need to pursue the design process management approach of identifying various decision-making frames to define the context of design activity. In this respect, the design process spectrum is compartmentalized into various decision frames to form the basis of design activity (Figure 2).
“Design activity”, in each frame, could then involve undertaking the CBA process of generating design options and going through the steps to establish the Importance of Advantages (IoA) of each design option to form the basis for a choice among the options. Therefore, under this approach, the CBA process is staged as a series of decision sessions timed to correspond with key decision pinch-points along the design process.
Identifying and predicting the various decision-making frames should be guided by the established value or requirements of the project, such that, decision frames identified as having significant impact on meeting project requirements and value are considered for CBA application. Target Value Design (TVD), which is a proven complement of the CBA process, should provide a useful premise in linking the identification and prediction of decision-making frames to project value and requirements. Decisions with high level of technical complexity as well as decisions with a high level of stakeholder interest could also be identified and framed for CBA application.
The role of a design manager / facilitator becomes crucial in coordinating the participation of stakeholders in identifying the various decision-making frames, and the eventual CBA application process within each frame. Participation of stakeholders may vary across the decision frames. For each of the decision-making frames, a key guiding principles in the choice of stakeholders to participate in the CBA process is to consider stakeholders with sufficient technical knowledge as well as those who can significantly influence, or significantly be influenced by the outcome of the decision frame.
The outcome of the CBA process should be summarized in its respective A3 reports, and then incorporated in the overall final design. The A3 reports, apart from providing useful reference for other design decisions, which are outside the identified frames but are within the spectrum, also become references documents for future decisions on the construction, operation and maintenance of the designed facility.
A Hypothetical Case
Consider a hypothetical case of designing a proposed auditorium for a university in Ghana in which pre-design discussions, between the design team and stakeholders, established the following key project requirements:
i) An auditorium that is strategically located for easy access by the university community and the public; and its use should not interfere with other key activities on the university campus (e.g. teaching and learning).
ii) The auditorium should emerge as a monumental icon to depict the university’s uniqueness and originality values.
iii) The auditorium should be energy efficient in use and maintenance.
Based on the established requirements, the design team, together with the other stakeholders, could then identify and anticipate the following frames of decision-making as being significant in contributing to the value of the project:
- Identifying project site / location
- Conceptualizing shape and layout
- Providing an envelope
- Providing window opening.
The respective design activities in each decision frame would involve applying the CBA decision-making system to decide on the location, conceptual layout, façade design, and window opening system for the project. The outcome of each of the CBA processes would be contained in its respective A3 reports. The final design of the auditorium should then incorporate recommendations in the A3 reports (Figure 3).
The nature of the CBA process, especially when using the tabular method, makes it impracticable to apply CBA on every design decision in a typical design process. Therefore, a feasible approach is to identify strategic decision-points across the design process, and then apply the tabular CBA process at those decision-points. Decisions that fall outside the strategic decision-points could be processed using the two-list or instant CBA method as may be appropriate.
 Suhr, J. (1999). The choosing by advantages decision making system. Wesport, CT: Quorum