The purpose of this paper is to improve the sustainability performance of an organization through implementing the Green Rating System (LEED).  The study was conducted at Petroleum Corporation in UAE. The Shewhart cycle (plan, do, check, and act) was used as a methodology. Both qualitative and quantitative data were collected and analyzed. As a result of assessing two building in the case study based on the green rating system (LEED) it was found that silver level is achieved. Consequently, relevant recommendations were generated, evaluated, and cost effective solutions were selected. The main results of the study showed that the organization can achieve a saving of at least 10 percent in the operating costs. Implementing LEED rating system accompanied by continuous improvement efforts can provide healthier working environments and enhance the sustainability performance, thus increasing the firm competitiveness.