Comparison of Green Building Rating Systems from LCA Perspective

Buildings account for a considerable proportion of carbon emissions throughout their lifecycle. Therefore, Green Building Rating Systems (GBRSs) have been developed globally to evaluate building environmental performance and mitigate their impacts on climate change. Life Cycle Assessment (LCA) as a science-based method has been recognised in the GBRSs to enhance the building environmental assessment. Regardless of the wide implementation of GBRSs, buildings carbon emissions have continued to rise by nearly 1% per year since 2010. Furthermore, no academic research has been conducted to compare GBRSs assessment criteria from the LCA perspective in respect of the recognition and weighting of (1) whole building LCA, (2) embodied carbon emissions and (3) operational carbon emissions. To this end, this research aims to evaluate the efficiency, validity and reliability of five international GBRSs (i.e., LEED, BREEAM, BEAM Plus, Green Star and Homestar) in terms of assessing and auditing the building total carbon emissions; embodied and operational emissions. Results show that conducting whole building LCA is an optional assessment criterion with negligible weighting. Moreover, the assessment of the operational carbon emissions make up the major portion of the total weighting in the existing GBRSs. By contrast, the assessment of building embodied carbon emissions is overlooked. Based on the results, shifting focus from operational carbon towards a full life cycle perspective is urgently needed to achieve the emissions reduction targets and so decarbonising the built environment.