Energy efficiency of buildings plays a paramount role in the European Commission (EC), who aims to achieve net-zero greenhouse gas emissions by 2050 in Europe through a socially-fair transition in a cost-efficient manner. The role of Energy Performance Certificates (EPCs) to boost building energy renovation is widely considered crucial in the literature because they are fundamental to provide better information to all the actors involved in the building renovation process. Besides, EPCs can act as a link between the different types of actions (institutional, financial, others) that will be needed to accomplish the building renovation goals. The crossCert project will create a product testing methodology for the new EPC approaches that will result in: improved accuracy and usability of the EPCs, people-centric designs, and increased homogeneity across Europe. The crossCert project is based on a bottom-up approach, with the following stages: (1) Cross-testing among energy authorities of current EPCs and the new approaches/concepts/initiatives, using more than 140 buildings in 10 European countries, and creating a public benchmarking repository of test cases; (2) Comparing and analysing the results between different approaches; (3) Elaboration of policy recommendations, which will include potential improvements on the accuracy, usability and harmonisation; (4) Engaging networks and alliances for analysis and (5) for outreach. Beyond accuracy, usability and harmonization, crossCert will use the cross-assessment exercise to conduct research and issue guidelines on: training and education of certified EPC issuers; EPC promotion and marketing; adapting EPCs investor needs; linking next-generation of EPCs to energy audits, logbooks and Building Renovation Passports; and EPCs and one-stop shops for building renovation.