The effectiveness of Green Building Rating systems in reducing embodied carbon

Embodied carbon (EC) emissions from construction today will lock-in warming and climatic changes for generations to come. In the UK and Ireland, EC is currently unregulated despite accounting for 8% and 14% of national emissions respectively and mitigation of EC at project level remains voluntary. Green Building Rating (GBR) systems such as BREEAM and LEED have become a key motivating factor for EC consideration at project level. This study investigates the robustness of GBR systems’ data requirements in supporting EC savings, and the influence these systems have on EC reduction strategies and outcomes. It examines two new-build projects seeking accreditation and compares project EC objectives and outcomes. The findings show that GBR systems present 'as-designed' EC data based on assumptions and the highest levels of accreditation can be awarded despite minimal to no accurate quantification. Without statutory oversight and a mandatory quantification framework within the GBR systems, the measurement of embodied carbon in future construction projects will remain highly uncertain and the ability to demonstrate meaningful embodied carbon savings will be limited.