Enhancement of iteration management in the design phase is important for successful offsite building projects. Design iteration has two aspects. Although iteration is necessary to deal with design requirements when solving complex problems (i.e. increasing quality through iteration), it has also been identified in numerous studies to be one of the main causes of design errors and time and cost overruns (i.e. superfluous iteration), as it increases scheduling and design complexity. Current building project management tools do not provide a means to control the reduction of superfluous iteration. One problem is that existing research has difficulty precisely relating the effects of specific management actions to superfluous iteration. The idea of this study is to develop an indicator, the sequence deviation quotient (SDQ), which reflects the amount of superfluous design iteration in a project. It can be thought of as a tool supporting project managers to make systematic and continuous (from project to project) design process improvement. A premise is that the impact of varying project conditions on the process structure of design processes, i.e. the precedence relationships between the design activities, is only small. In this paper, we provide a definition of superfluous iteration. We tested the feasibility of the SDQ by subjecting it to project variation and input perturbation by means of a Monte Carlo simulation. The simulations are based on the data from a real offsite design building process, the designing of a 1100 m2 residential building in Sweden.

Timber building structures are seldom considered because of a lack of timber construction knowledge among many clients and professionals. 3D computer visualization (3D VIZ) is a possible way of communicating the aesthetics of a visible timber structure and visualizing complex timber connections. This paper investigates the potential for 3D VIZ to communicate visible timber structures during the different phases of the construction process. Furthermore, important parameters (controllable in 3D VIZ) for communicating a timber structure are identified. Through an Internet-based Delphi study, the usefulness of 3D VIZ for timber structures has been evaluated by professionals representing different competencies in the construction process. The results show that structural complexity, intended beholder (professional or non-professional) and current construction phase influence the benefit of 3D VIZ. The level of detail in the visualization is heavily dependent on whether the communication is internal (between professionals) or external (between professionals and clients/users). The impact of parameters needed, such as textures, surface structures and realistic lighting, have been described.