Embodied carbon of concrete in buildings, Part 1: Analysis of published EPD

Cement is responsible for 7% of global greenhouse gas emissions, and is predicted to grow with increasing development. The majority is used in concrete, globally the most common material in buildings. Reducing emissions from the use of cement and concrete in buildings is therefore critical in order to limit global warming. However there remain multiple gaps in knowledge about the extent of these emissions. This paper is the first output of a project that aims to understand better the embodied impacts from the use of concrete in buildings, in order to inform and advise policy-makers and industry practitioners, and to provide clear evidence for the path forwards. In order to do so, the project collates, analyses and critiques evidence from multiple sources, reported over three papers. This first paper focuses on the basic data on materials impacts. Over the last few years, several hundred individual Environmental Product Declarations (EPD) have been published for cements, aggregates and concrete mixes, but no publication offers a comparison or overview. Therefore understanding the range and opportunities for the reduction of impacts from concrete remains very limited. This paper provides the first detailed analysis of the EPD for concrete and its constituents. Practice relevance The graphs developed in this paper can be used by designers and manufacturers to understand and reduce the impacts from cement and concrete. Designers will have a better idea of an appropriate coefficient to use at the early design stage before more details are known. As the design progresses, they will be able to use the graphs presented to choose a lower impact cement or concrete with the same performance, as well as to check the likely validity of any EPD. The graphs also provide an incentive to manufacturers to reduce impacts, since they will now be able to compare their products with others. Finally, for those involved in producing EPD, the paper demonstrates the necessity of more detailed rules for consistency, and in the meantime the necessity of full transparency in EPD reports.