Evolution of lighting-related credit achievement in LEED-certified buildings: A comparative study of LEED v2009 and LEED v4 in the United Arab Emirates

Sustainable buildings play a central role in reducing environmental impacts while improving resource efficiency and occupant well-being. To evaluate and promote sustainable building practices, green building rating systems have become widely adopted worldwide, with the Leadership in Energy and Environmental Design (LEED) framework being one of the most influential. As LEED has evolved from version 2009 to version 4, its lighting-related credits have shifted towards more performance-oriented and climate-responsive assessment methods. However, limited evidence exists on how these revisions have influenced lighting-related certification outcomes, particularly in hot-arid regions. This study evaluates lighting-related credit achievement following the transition from LEED v2009 (LV09) to LEED v4.0 (LV4) using a mixed-methods approach. A verified dataset of 100 LEED-certified projects was compiled, including a directly comparable subset of 69 New Construction projects (38 LV09 and 31 LV4), complemented by a qualitative review of 25 selected projects. The results show substantial improvements in Daylight (DL) credit achievement (5.3% to 45.2%) and Light Pollution Reduction (LPR) (13.2% to 61.3%) under LV4, while Quality Views (QV) remained broadly unchanged. The qualitative review identified recurring strategies involving climate-responsive daylighting, façade and solar-control measures, efficient electric-lighting systems, automated controls, and exterior-lighting management. Overall, the findings indicate that the transition to LV4 was associated with credit-specific improvements rather than uniform enhancement across all lighting categories. This study provides one of the first comprehensive evaluations of lighting-related LEED certification outcomes in a hot-arid context and offers practical evidence to support future refinement of green building assessment frameworks. The findings represent certification outcomes and documented design strategies rather than direct measurements of operational lighting performance.