Utilization of life-cycle analysis to evaluate sustainability rating systems for construction projects with a case study on qatar sustainability assessment system (qsas)

The purpose of this paper is to present a methodology for assessing, in quantifiable terms, the reduction in environmental impacts achieved by applying different credits of sustainability rating systems in building construction projects. Sustainability rating systems are developed in various regions to evaluate construction projects with respect to their environmental performance. Although implementation of rating systems had a recognized effect on reducing environmental impact of construction projects, there is no objective and quantifiable evidence that the approaches recommended by these rating systems to achieve the required certification lead to optimum environmental results. This paper presents a methodology that utilizes life cycle analysis (LCA) as a powerful and objective tool to validate the way rating systems evaluate project performance. The Qatar Sustainability Assessment System (QSAS), recently developed in the State of Qatar by Gulf Organization for Research and Development (GORD), is chosen as a case study to illustrate application of the developed methodology. Environmental impacts due to implementation of QSAS credits are calculated for one project in Qatar, which is currently under construction. Results reveal possible use of LCA as a tool for evaluating the effectiveness of rating systems. For the QSAS case study, findings reveal indications of over and, in some instances, under estimation of the weights assigned to some credits and the difficulty in the quantification of the impacts of other credits, which indicates the need for reconsideration of these weights to improve effectiveness of the implementation of these credits. The proposed methodology stands as a step toward the enhancement and rationalization of the currently used building sustainability ratings system.