Project based learning (PjBL) can be an effective approach to developing graduate attributes, but it depends on how it is implemented. Chemical Engineering of RMIT University has a stream of PjBL subjects from first to final year. The projects are incrementally more complex but have the same goal: to choose a best process design, using management decision making tools to justify their choices. The tools include GEMI Metrics NavigatorTM. This paper reports an evaluation of whether students’ understanding of sustainability is enhanced by undertaking multiple projects, as well as use of sophisticated analysis tools. Student learning outcomes from intermediate and final subjects were compared using ConceptMaps and a focus group. The students’ understanding of sustainability increased substantially from 2nd to final year, similar to results reported in European studies. The spread of results was broad, attributed to range of student ability and differences between student cohorts. Development of understanding of sustainability was attributed to undertaking multiple projects and use of spread-sheeting tools. Use of the GEMI tool was identified as facilitating application of sustainability principles to process design decisions. Concept maps are a useful way to evaluate innovations in teaching sustainable engineering.