Energy performance certificates (EPC) were introduced in European Union to support reaching energy efficiency targets by informing actors in the building sector about energy efficiency in buildings. While EPC have become a core source of information about building energy, the domains of its applications have not been studied systematically. This partly explains the limitation of conventional EPC data quality studies that fail to expose the essential problems and secure effective use of the data. This study reviews existing applications of EPC data and proposes a new method for assessing the quality of EPCs using data analytics. Thirteen application domains were identified from systematic mapping of 79 papers, revealing increases in the number and complexity of studies and advances in applied data analysis techniques. The proposed data quality assurance method based on six validation levels was tested using four samples of EPC dataset for the case of Sweden. The analysis showed that EPC data can be improved through adding or revising the EPC features and assuring interoperability of EPC datasets. In conclusion, EPC data have wider applications than initially intended by the EPC policy instrument, placing stronger requirements on the quality and content of the data.