Life cycle assessment (LCA) has been conducted to obtain the potential reduction in the environmental impact due to the production of limestone calcined clay cement (LC3), with respect to ordinary portland cement (OPC) and fly ash-based portland pozzolana cement (PPC). A case study of a typical cement plant in South India is considered. It is found, for this particular case and the assumptions made, that the CO2 emissions and the energy demand could decrease by 34% and 18%, respectively, if LC3 is used instead of OPC, with the corresponding reductions being 26% and 21% for PPC. A parametric study of some key factors that could influence the impact of LC3 showed that the CO2 emissions and the energy demand could vary by 13% and 20%, respectively, with variations in the calcination energy requirement while the clay transportation distance did not have any significant influence. © RILEM 2020.