Layered project-layered process: Lean thinking and flexible solutions

This article elaborates on lean thinking in design management. Lean philosophy focuses on minimizing waste and maximizing value. We discuss how lean concepts can be understood and how this can affect the design process. In particular, we examine how flexibility can be achieved through the use of a layered design process and a layered building design. The design process has two main outcomes: input to the production and/or construction process, and input to the decision process. These two outcomes have a number of contradictory characteristics. Traditionally, production processes call for early decisions and control of cost, time and risks. Typically, this has been the engineers' or the contractors' perspective. In contrast, the decision process typically strives to postpone final commitments and design freeze in order to keep options open. Lean thinking shows that the two approaches do not have to be contradictory. Based on case studies of two hospital projects, we discuss flexibility in the design process and design in relation to lean principles. The article demonstrates the importance of seeing the design process and design model as two integrated parts. Lean thinking can serve as an enabler by focusing on reducing waste and increasing the customer's value.