The conceptual design stage is perhaps the most critical. At this stage design information is often incomplete, contradictory or inconsistent. The designer is also confronted by what seems at first to be a universe of possible design solutions. Decisions made at this stage will determine the framework for the final design solution. The final design, which is developed from the design concept, should reflect the satisfaction of and between the many constraints and limitations imposed on the design.
Design involves deciding between alternative courses of action.
Not all decisions are critical and the designer needs to ascertain which ones are critical according to the state of development of the design, ie, concept, intermediate, detail. Because design solutions unfold in stages, decisions are often made tentatively and are subsequently reassessed in light of further developments. Further, the activities involved in design are often relatively routine and common to most buildings of the same type. Recent design tradition seems to treat each building design problem de novo, as though it had never occurred before. In fact the majority of buildings that are built are answers to problems and needs that are not significantly different from the problems and needs that both contemporary and earlier buildings have already solved and served.