Abstract Demand for new buildings and infrastructure continues to grow and will only increase in coming years to cater for forecast growth in global population. This demand will result in considerable strain on the natural environment, resulting from the operation of these new built assets as well as the demand for resources required to construct and maintain them. Life cycle assessment is a tool that can be used during the design or refurbishment of new or existing buildings or infrastructure projects, to assess and improve their environmental performance. A life cycle assessment is often time consuming and complex, especially when used for the analysis of entire construction projects. This is particularly true when it is used to analyse construction-related, or embodied, environmental flows (e.g. embodied greenhouse gas emissions). To simplify the process, especially with projects that have tight time or budget constraints, product-based environmental flow coefficients are often used, which provide an indication of the environmental flows associated with specific construction materials. However, existing coefficients are typically based on process data, inherent with truncated product system boundaries. This paper introduces the Environmental Performance in Construction (EPiC) Database, a comprehensive database of hybrid embodied environmental flow coefficients for construction materials in Australia. EPiC uses a hybrid life cycle inventory approach to fill the gaps that exist in process data and provide embodied environmental flow coefficients that are systemically complete. This study has shown that existing process data for materials is on average 55% incomplete, but considerable inconsistency in system boundary coverage means that this incompleteness varies from 2% to 99% across materials and environmental flows. Other key strengths of EPiC are its transparency, providing open access to all data, and methodological consistency, with coefficient data sources and methods being the same for all materials. Environmental flow coefficients from EPiC can be used on their own or integrated into existing life cycle assessment tools, informing improvements to the environmental performance of construction projects.