Emergence is a phenomenon that a set of agents which obeying simple rules locally defined generates interpretive global structures, which is not predictable from the rules. In the context of engineering design, concept of emergence is often referred to as generator of new designs which looks impressive and something new. In this paper, the authors consider use of the emergence for engineering design in a different perspective. Nowadays, various computer simulations are being used in a large number of design fields. It has, however, a fundamental limitation. They assume well-posed problems(in mathematical sense) as their problems to be deal with, and ill-posed problems are eliminated from their scopes legitimately. In early design stages, however, design problems are often described incompletely and contradictory. Hence, corresponding simulation problems would be ill-posed. These situations are a kind of blind-corner of current simulation technologies, but important in practical sense. The authors argue here that involving the emergence property in simulation enables to handle the illness of such design problems. Beginning with a brief introduction of emergence concept and preceding researches, our emergence based calculation scheme is proposed. Property of the proposed scheme is considered by comparing with a standard form of numerical simulation, followed by results of numerical experiments, which show its calculation performance and property.