A decision making support model to determine appropriate credits for green building certification based on project delivery attributes

Green building (GB) projects require elevated levels of interdependency and interconnectedness of different technical disciplines to respond for the needs of integrated green design systems which definitely cause higher complexities throughout the processes of GB compared to the non-green buildings (NGBs). High levels of complexity in GB processes not only create higher time and cost related waste but also other specific types of waste throughout the GB project delivery process compared to the NGBs. Prior studies identified some of the waste types and related root causes for GB projects; however, a comprehensive identification and classification of waste and related root causes still remains to be a crucial necessity for the GB industry and GB literature. Waste generation within the GB project delivery process directly relates to the question whether the GB objectives and requirements can be fulfilled by the existing attributes of the project delivery team or not. Particularly, GB certification process embodies detailed requirements and specifications that lead to additional tasks for the project team which altogether elevate complexity levels of the whole project delivery process. In order to achieve GB certification, initially credits need to be selected among a large set of credits categorized under the GB rating system. Then the requirements of these selected credits and the GB rating system must be satisfied by the project and project teams. If selected GB certification credits are not suitable for the project team related GB project delivery attributes, elevated levels of time, money and labor could get wasted while attempting to fulfill the additional requirements of GB design, construction and certification. Considering GB project attributes is critical for the analysis and optimization of GB project delivery since project attributes affect the outcomes that determine the overall success of GB projects. Hence, there is an obvious necessity for having a decision-making model to tackle with the complexities of GB projects and provide a guideline for determining appropriate GB certification credits in accordance with the project delivery attributes; however, such a model is currently absent in the GB literature. This Ph.D. study addresses these needs by (1) by examining waste and related root causes in detail for GB project delivery process, (2) analyzing project delivery attributes that play major role in ensuring successful completion of GB projects under a hierarchical framework, and (3) developing a multi-attribute decision making support model from this hierarchical framework to determine resource efficient credits for GB certification. On the road of developing a decision making support model, I initially identified and classified waste types and related root causes, then investigated the cause-effect relation between them by ranking them according to their negative impacts on time and cost in design and construction phases of GB project delivery process determined from a case study that includes three GB projects and performing a two-rounded Delphi Method. Drawing from my findings, I focused on two GB project delivery attributes, i.e. timing of project teams’ involvement and qualifications of project teams, which play a crucial role for ensuring successful completion of GB projects while enduring minimal waste in GB project delivery process. Based on these two attributes, I built a hierarchical framework to assign relative weights to these attributes, and to constitute the basis of my decision making support model. Towards the achievement of my grand vision, I developed this hierarchical framework into an integrated decision making support model, namely Green Building-Credit Selection (GB-CS) Model, to determine appropriate and resource efficient (i.e. time, cost and labor) GB certification credits that suit the particular attributes of GB project delivery. The GB-CS Model employs the combined use of Delphi Method based weight assignment approach and TOPSIS. The GB-CS Model (1) designates relative weights to hierarchically designed project delivery attributes through Delphi Method based weight assignment process, and (2) determines appropriate credits in accordance with GB project delivery attributes via TOPSIS. I developed the GB-CS Model based on LEED® 2009 NC under BD+C Rating System. I tested and validated the GB-CS Model by conducting a case study on a LEED® registered residential project. This integrated study formalizes the identification and classification of process waste with their related root causes for GB projects and reveals the cause-effect relationship between them which come together as a multi-attribute decision making support model that aid the optimization of GB project delivery and allows obtaining better outcomes from GB projects through minimizing the root causes of elevated waste and mitigating associated hidden costs. This multi-attribute model provides an interconnected decision making guideline which assesses the particular conditions of the project and project team before deciding to follow a GB rating system and determines the appropriate GB certification credits that are more likely to be obtained in an efficient and effective manner considering the particular attributes of GB project delivery. Properly selected GB certification credits would optimize GB project delivery by mitigating the excess levels of waste generated to fulfill the additional requirements of GB design, construction and certification. The GB-CS Model proposes to give the GB industry and literature the upper hand by facilitating GB project delivery with an adaptive guidance model that quantifies the outcomes of Green decisions and ensures the successful completion of GB projects.