This work explores the effectiveness of design postponement in the concept development of large-scale engineering projects. Our empirical research shows limited use of postponement in semiconductor fabrication facility (fab) projects despite evidence that the customer inevitably requests design criteria changes in the projects life. We simulate fab concept development as a 2-stage process—conceptualization followed by design. We find that postponing the start of design in relation to the completion of conceptualization reduces the average resources spent on design and the variability in the concept development duration but increases the average concept development duration. A sensitivity analysis on the postponement lag duration indicates, however, that some degree of postponement may allow reducing design rework without increasing the risk of overrunning the project completion date, in comparison to the risk with early commitment. Further, simulation indicates that the effectiveness of postponement decreases as designers capability to reuse work increases.