Innovation projects has established as an emerging field of research, a number of issues have emerged; among the others, measurability and predictability of product development. Moreover, whilst great relevance has been given to aspects such as innovation factors, product results, cognitive knowledge, poor attention has been given to other fundamental factors: product development process and effectiveness of design process as a consequence of complex problem situation. A formalization in affordances of design process may help overcome said issues and enhance product effectiveness, by identifying and highlighting potential designers' workload perception during the Product Development Process. In this scenario, this paper describes an approach for continuously monitoring and measuring the complexity of design process during the creation of a new product. After an overview of the related work, this study proposes a common instructional design model for Product Development Process, which was split in order to be measured by using NASA-TLX. This research propose that the use of NASA-TLX to predict and measure the designer workload during the design process contributes to a better understanding of the relationships among the different design phases and designer workload. After having shown a case study, a discussion about the possible developments, as well as the limitations of the proposed method, concludes this work.