Substituting local data for overseas life cycle inventories - a case study of concrete products in Hong Kong

Life cycle assessment has been widely adopted to evaluate the environmental impacts of a product. In many cases, a local life cycle inventory (LCI) is not available and the substitution of overseas LCIs by local data has become a common practice. Although substituting local data into existing LCIs is considered as an efficient way to create a 'partially localized' inventory, little has been known on the consequences of such adjustments, not to mention about the availability of a standard governing this issue. This study investigates the changes caused by replacing overseas LCIs with local data and provides suggestions based on a case study of concrete production in Hong Kong. Two existing overseas LCI datasets are used, namely Ecoinvent and US PCA. Thirty localized scenarios are performed at three different levels and the localized scenarios are compared with the two original datasets. The results indicate that the change of single score increases with the adjustments in the original LCIs. It is found that the substitution of local data into US PCA and Ecoinvent would yield different changes, despite the same adjustments are performed. The changes in the localized concrete datasets are mainly attributed to the adjustments of cement and transportation. Based on the research findings, it is suggested to examine the changes due to the data substitution and define the levels of adjustment. The percentage of adjustment should also be specified. The research findings of this study shall pave a way for the standardization of the adaptation of overseas LCIs in the future.