Abstract
The construction industry will play a crucial rule in global carbon emission reduction as the embodied carbon of construction materials shares an increasing portion of a building's life-cycle carbon dioxide (CO2) emissions. In order to reduce CO2 emissions by selecting low-carbon construction materials, it is inevitable that a proper benchmarking mechanism and severity representation of different emission levels should be established, as benchmarking is a useful tool for pursuing consumer purchasing habits toward selection of low-carbon materials. In addition, high variation of carbon emissions is observed among the large number of studies and databases, and there is no consensus on how these should be used in practice. Therefore, standardization and benchmarking of emissions for construction materials are essential. In this study, a novel benchmarking approach was developed for embodied carbon emissions of commonly used construction materials by applying a fuzzy set theory. Given that a reliable local database is lacking, the benchmark was developed by referring to the existing carbon inventories, linguistic variables of severity levels from a questionnaire survey, and the fuzzy set analysis. A six-step method was proposed based on a horizontal and graphical approach. This study offers an alternative approach in benchmarking where a database or a set of real data is not available. It is expected that the developed benchmarks will help practitioners and decision-makers compare the embodied CO2 emissions of a specific batch of construction materials and select low-carbon materials in construction projects.