In the object-oriented paradigm, as complexity rises, the cost of developing and maintaining software systems grows exponentially. This complexity emerges from the continuous evolution of software systems to cope with changing requirements. This crucial problem can be dealt with by performing an active transformation of the elements (i.e. classes and relations) of the conceptual model to produce an optimum design model. We show transformations for a simple conceptual model consisting of three inter-related classes. Each of these transformations satisfies particular software quality factor(s), from which the software engineer can choose the one that matches the intended non-functional requirements. The added value of this approach is that less manual optimization is required and high maintenance is achieved.