Conceptual design is one of the most important activities in new product development. Inappropriate design concepts could result in high redesign cost and delay in product realisation. The generation of conceptual designs is a time-consuming and mentally exhausting process. It involves combining design features to generate as many potential design concepts as possible. As not all features combinations are feasible, decision-makers have to narrow down the potential solutions and subsequently select appropriate concept(s) for further development. This work concerns the automation of the conceptual design process using an evolutionary strategy. The paper proposes a design attribute encapsulation method, which is applied to the chromosome representation of the design concept, to facilitate the search for a promising combination of features. The design of golf clubs for children is used to illustrate the application of the proposed approach. Mathematical analysis shows that with the proposed approach, the probability of generating a feasible concept during the mutation and crossover is higher with better use of the feasibility rules.