This document supports the data quality assessment and selection of data for product-level Environmental Product Declarations (EPD) according to the core product category rules of EN 15804 and for the environmental performance assessment of buildings according to prEN 15978-1 in a consistent way. It can also be used to assess and select data for the environmental assessment of civil engineering works according to EN 17472. It defines data quality requirements with respect to temporal, technological and geographical representativeness for the data used to calculate the Life Cycle Assessment (LCA) based indicator results of the EPD and for construction works when applying EPD, life cycle inventory data or other LCA based information, and generates a hierarchy to support the selection of the most appropriate data with regard to data quality. It also addresses the reporting of data quality at product and building level.